Publications by authors named "Cynthia L Leibson"

67 Publications

Venous Thromboembolism (VTE) Incidence and VTE-Associated Survival among Olmsted County Residents of Local Nursing Homes.

Thromb Haemost 2018 Jul 2;118(7):1316-1328. Epub 2018 Jul 2.

Division of Epidemiology, Department of Health Sciences Research, College of Medicine, Mayo Clinic, Rochester, Minnesota, United States.

Nursing home (NH) residency is an independent risk factor for venous thromboembolism (VTE), but the VTE burden within the NH population is uncertain. This study estimates VTE incidence and VTE-associated mortality among NH residents. We identified all NH residents in any NH in Olmsted County, Minnesota, United States, 1 October 1998 to 31 December 2005 and all first lifetime VTE among county residents to estimate VTE incidence while resident of local NHs (NHVTE), using Centers for Medicare and Medicaid Services Minimum Data Set and Rochester Epidemiology Project resources. We tested associations between NHVTE and age, sex and time since each NH admission using Poisson modelling. Additionally, we tested incident NHVTE as a potential predictor of survival using Cox proportional hazards, adjusting for age, sex and NH residency. Between 1 October 1998 and 31 December 2005, 3,465 Olmsted County residents with ≥1 admission to a local NH, contributed 4,762 NH stays. Of the 3,465 NH residents, 111 experienced incident NHVTE (2.3% of all eligible stays), for an overall rate of 3,653/100,000 NH person-years (NH-PY). VTE incidence was inversely associated with time since each NH admission, and was highest in the first 7 days after each NH admission (18,764/100,000 NH-PY). The adjusted hazard of death for incident NHVTE was 1.90 (95% confidence interval [CI]: 1.38-2.62). In conclusion, VTE incidence among NH residents was nearly 30-fold higher than published incidence rates for the general Olmsted County population. VTE incidence was highest within 7 days after NH admission, and NHVTE was associated with significantly reduced survival. These data can inform future research and construction of clinical trials regarding short-term prophylaxis.
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http://dx.doi.org/10.1055/s-0038-1660436DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6206861PMC
July 2018

Nursing Home Use Across The Spectrum of Cognitive Decline: Merging Mayo Clinic Study of Aging With CMS MDS Assessments.

J Am Geriatr Soc 2017 Oct 11;65(10):2235-2243. Epub 2017 Sep 11.

Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota.

Background/objectives: Objective, complete estimates of nursing home (NH) use across the spectrum of cognitive decline are needed to help predict future care needs and inform economic models constructed to assess interventions to reduce care needs.

Design: Retrospective longitudinal study.

Setting: Olmsted County, MN.

Participants: Mayo Clinic Study of Aging participants assessed as cognitively normal (CN), mild cognitive impairment (MCI), previously unrecognized dementia, or prevalent dementia (age = 70-89 years; N = 3,545).

Measurements: Participants were followed in Centers for Medicare and Medicaid Services (CMS) Minimum Data Set (MDS) NH records and in Rochester Epidemiology Project provider-linked medical records for 1-year after assessment of cognition for days of observation, NH use (yes/no), NH days, NH days/days of observation, and mortality.

Results: In the year after cognition was assessed, for persons categorized as CN, MCI, previously unrecognized dementia, and prevalent dementia respectively, the percentages who died were 1.0%, 2.6%, 4.2%, 21%; the percentages with any NH use were 3.8%, 8.7%, 19%, 40%; for persons with any NH use, median NH days were 27, 38, 120, 305, and median percentages of NH days/days of observation were 7.8%, 12%, 33%, 100%. The year after assessment, among persons with prevalent dementia and any NH use, >50% were a NH resident all days of observation. Pairwise comparisons revealed that each increase in cognitive impairment category exhibited significantly higher proportions with any NH use. One-year mortality was especially high for persons with prevalent dementia and any NH use (30% vs 13% for those with no NH use); 58% of all deaths among persons with prevalent dementia occurred while a NH resident.

Conclusions: Findings suggest reductions in NH use could result from quality alternatives to NH admission, both among persons with MCI and persons with dementia, together with suitable options for end-of-life care among persons with prevalent dementia.
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http://dx.doi.org/10.1111/jgs.15022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5657551PMC
October 2017

Skilled Nursing Facility Use and Hospitalizations in Heart Failure: A Community Linkage Study.

Mayo Clin Proc 2017 Mar 13. Epub 2017 Mar 13.

Department of Health Sciences Research, Mayo Clinic, Rochester, MN; Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, MN; Center for the Science of Health Care Delivery, Mayo Clinic, Rochester, MN. Electronic address:

Objectives: To examine the effect of skilled nursing facility (SNF) use on hospitalizations in patients with heart failure (HF) and to examine predictors of hospitalization in patients with HF admitted to a SNF.

Patients And Methods: Olmsted County, Minnesota, residents with first-ever HF from January 1, 2000, through December 31, 2010, were identified, and clinical data were linked to SNF utilization data from the Centers for Medicare and Medicaid Services. Andersen-Gill models were used to determine the association between SNF use and hospitalizations and to determine predictors of hospitalization.

Results: Of 1498 patients with incident HF (mean ± SD age, 75±14 years; 45% male), 605 (40.4%) were admitted to a SNF after HF diagnosis (median follow-up, 3.6 years; range, 0-13.0 years). Of those with a SNF admission, 225 (37%) had 2 or more admissions. After adjustment for age, sex, ejection fraction, and comorbidities, SNF use was associated with a 50% increased risk of hospitalization compared with no SNF use (adjusted hazard ratio, 1.52; 95% CI, 1.31-1.76). In SNF users, arrhythmia, asthma, chronic kidney disease, and the number of activities of daily living requiring assistance were independently associated with an increased risk of hospitalization.

Conclusion: Approximately 40% of patients with HF were admitted to a SNF at some point after diagnosis. Compared with SNF nonusers, SNF users were more likely to be hospitalized. Characteristics associated with hospitalization in SNF users were mostly noncardiovascular, including reduced ability to perform activities of daily living. These findings underscore the effect of physical functioning on hospitalizations in patients with HF in SNFs and the importance of strategies to improve physical functioning.
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http://dx.doi.org/10.1016/j.mayocp.2017.01.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5597448PMC
March 2017

Risk factors for venous thromboembolism after acute trauma: A population-based case-cohort study.

Thromb Res 2016 Aug 29;144:40-5. Epub 2016 Mar 29.

Mayo Clinic, 200 First Street, SW, Rochester, MN 55905, United States.

Background: Predictors of venous thromboembolism (VTE) after trauma are uncertain.

Objective: To identify independent predictors of VTE after acute trauma.

Methods: Using Rochester Epidemiology Project (REP) resources, we identified all Olmsted County, MN residents with objectively-diagnosed incident VTE within 92days after hospitalization for acute trauma over the 18-year period, 1988-2005. We also identified all Olmsted County residents hospitalized for acute trauma over this time period and chose one to two residents frequency-matched to VTE cases on sex, event year group and ICD-9-CM trauma code predictive of surgery. In a case-cohort study, demographic, baseline and time-dependent characteristics were tested as predictors of VTE after trauma using Cox proportional hazards modeling.

Results: Among 200 incident VTE cases, the median (interquartile range) time from trauma to VTE was 18 (6, 41) days. Of these, 62% cases developed VTE after hospital discharge. In a multiple variable model including 370 cohort members, patient age at injury, male sex, increasing injury severity as reflected by the Trauma Mortality Prediction Model (TMPM) Mortality Score, immobility prior to trauma, soft tissue leg injury, and prior superficial vein thrombosis were independent predictors of VTE (C-statistic=0.78).

Conclusions: We have identified clinical characteristics which can identify patients at increased risk for VTE after acute trauma, independent of surgery. Almost two thirds of all incident VTE events occurred after initial hospital discharge (18day median time from trauma to VTE) which questions current practice of not extending VTE prophylaxis beyond hospital discharge.
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http://dx.doi.org/10.1016/j.thromres.2016.03.026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5124558PMC
August 2016

Direct Medical Costs Attributable to Cancer-Associated Venous Thromboembolism: A Population-Based Longitudinal Study.

Am J Med 2016 09 21;129(9):1000.e15-25. Epub 2016 Mar 21.

Division of Cardiovascular Diseases and Gonda Vascular Center, Department of Internal Medicine, Mayo Clinic, Rochester, Minn; Division of Epidemiology, Department of Health Sciences Research, Mayo Clinic, Rochester, Minn; Division of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, Minn. Electronic address:

Purpose: The purpose of this study is to estimate medical costs attributable to venous thromboembolism among patients with active cancer.

Methods: In a population-based cohort study, we used Rochester Epidemiology Project (REP) resources to identify all Olmsted County, Minn. residents with incident venous thromboembolism and active cancer over the 18-year period, 1988-2005 (n = 374). One Olmsted County resident with active cancer without venous thromboembolism was matched to each case on age, sex, cancer diagnosis date, and duration of prior medical history. Subjects were followed forward in REP provider-linked billing data for standardized, inflation-adjusted direct medical costs from 1 year prior to index (venous thromboembolism event date or control-matched date) to the earliest of death, emigration from Olmsted County, or December 31, 2011, with censoring on the shortest follow-up to ensure a similar follow-up duration for each case-control pair. We used generalized linear modeling to predict costs for cases and controls and bootstrapping methods to assess uncertainty and significance of mean adjusted cost differences. Outpatient drug costs were not included in our estimates.

Results: Adjusted mean predicted costs were 1.9-fold higher for cases ($49,351) than for controls ($26,529) (P < .001) from index to up to 5 years post index. Cost differences between cases and controls were greatest within the first 3 months (mean difference = $13,504) and remained significantly higher from 3 months to 5 years post index (mean difference = $12,939).

Conclusions: Venous thromboembolism-attributable costs among patients with active cancer contribute a substantial economic burden and are highest from index to 3 months, but may persist for up to 5 years.
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http://dx.doi.org/10.1016/j.amjmed.2016.02.030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4996698PMC
September 2016

Childhood Attention-Deficit/Hyperactivity Disorder, Sex, and Obesity: A Longitudinal Population-Based Study.

Mayo Clin Proc 2016 Mar 4;91(3):352-61. Epub 2016 Feb 4.

Division of Epidemiology, Mayo Clinic, Rochester, MN.

Objective: To assess obesity rates during childhood and young adulthood in patients with attention-deficit/hyperactivity disorder (ADHD) and age- and sex-matched controls derived from a population-based birth cohort because cross-sectional studies suggest an association between ADHD and obesity.

Patients And Methods: Study subjects included patients with childhood ADHD (n=336) and age- and sex-matched non-ADHD controls (n=665) from a 1976 to 1982 birth cohort (N=5718). Height, weight, and stimulant treatment measurements were abstracted retrospectively from medical records documenting care provided from January 1, 1976, through August 31, 2010. The association between ADHD and obesity in patients with ADHD relative to controls was estimated using Cox models.

Results: Patients with attention-deficit/hyperactivity disorder were 1.23 (95% CI, 1.00-1.50; P<.05) times more likely to be obese during the follow-up period than were non-ADHD controls. This association was not statistically significant in either sex (female participants: hazard ratio [HR], 1.49; 95% CI, 0.98-2.27; P=.06; male participants HR, 1.17, 95% CI, 0.92-1.48; P=.20). Patients with ADHD who were not obese as of the date ADHD research diagnostic criteria were met were 1.56 (95% CI, 1.14-2.13; P<.01) times more likely to be obese during the subsequent follow-up than were controls. This association was statistically significant in female study subjects (HR, 2.02; 95% CI, 1.13-3.60; P=.02), but not in male participants (HR, 1.41; 95% CI, 0.97-2.05; P=.07). A higher proportion of patients with ADHD were obese after the age of 20 years compared with non-ADHD controls (34.4% vs 25.1%; P=.01); this difference was observed only in female patients (41.6% vs 19.2%). There were no differences in obesity rates between stimulant-treated and nontreated patients with ADHD.

Conclusion: Childhood ADHD is associated with obesity during childhood and young adulthood in females. Treatment with stimulant medications is not associated with the development of obesity up to young adulthood.
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http://dx.doi.org/10.1016/j.mayocp.2015.09.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5264451PMC
March 2016

Trends in Coronary Atherosclerosis: A Tale of Two Population Subgroups.

Am J Med 2016 Mar 6;129(3):307-14. Epub 2015 Nov 6.

Department of Health Sciences Research, Mayo Clinic, Rochester, Minn. Electronic address:

Background: We previously investigated trends in subclinical coronary artery disease and associated risk factors among autopsied non-elderly adults who died from nonnatural causes. Although grade of atherosclerosis declined from 1981 through 2009, the trend was nonlinear, ending in 1995, concurrent with increasing obesity/diabetes in this population. The previous study used linear regression and examined trends for all 4 major epicardial coronary arteries combined. The present investigation of coronary artery disease trends for the period 1995 through 2012 was prompted by a desire for more detailed examination of more recent coronary artery disease trends in light of reports that the epidemics of obesity and diabetes have slowed and are perhaps ending.

Methods: This population-based series of cross-sectional investigations identified all Olmsted County, Minnesota residents aged 16-64 years who died 1995 through 2012 (N = 2931). For decedents with nonnatural manner of death, pathology reports were reviewed for grade of atherosclerosis assigned each major epicardial coronary artery. Using logistic regression, we estimated calendar-year trends in grade (unadjusted and age- and sex-adjusted) for each artery, initially as an ordinal measure (range, 0-4); then, based on evidence of nonproportional odds, as a dichotomous variable (any atherosclerosis, yes/no) and as an ordinal measure for persons with atherosclerosis (range, 1-4).

Results: Of 474 nonnatural deaths, 453 (96%) were autopsied; 426 (90%) had coronary stenosis graded. In the ordinal-logistic model for trends in coronary artery disease grade (range, 0-4), the proportional odds assumption did not hold. In subsequent analysis as a dichotomous outcome (grades 0 vs 1-4), each artery exhibited a significant temporal decline in the proportion with any atherosclerosis. Conversely, for subjects with coronary artery disease grade 1-4, age- and sex-adjusted ordinal regression revealed no change over time in 2 arteries and statistically significant temporal increases in severity in 2 arteries.

Conclusions: Findings suggest that efforts to prevent coronary artery disease onset have been relatively successful. However, statistically significant increases in the grade of atherosclerosis in 2 arteries among persons with coronary artery disease may be indicative of a major public health challenge.
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http://dx.doi.org/10.1016/j.amjmed.2015.10.032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4755914PMC
March 2016

Costs of venous thromboembolism associated with hospitalization for medical illness.

Am J Manag Care 2015 Apr 1;21(4):e255-63. Epub 2015 Apr 1.

Stabile 6-Hematology Research, Mayo Clinic, 200 First St, SW, Rochester, MN 55905. E-mail:

Objectives: To determine population-based estimates of medical costs attributable to venous thromboembolism (VTE) among patients currently or recently hospitalized for acute medical illness.

Study Design: Population-based cohort study conducted in Olmsted County, Minnesota.

Methods: Using Rochester Epidemiology Project (REP) resources, we identified all Olmsted County residents with objectively diagnosed incident VTE during or within 92 days of hospitalization for acute medical illness over the 18-year period of 1988 to 2005 (n=286). One Olmsted County resident hospitalized for medical illness without VTE was matched to each case for event date (±1 year), duration of prior medical history, and active cancer status. Subjects were followed forward in REP provider-linked billing data for standardized, inflation-adjusted direct medical costs (excluding outpatient pharmaceutical costs) from 1 year before their respective event or index date to the earliest of death, emigration from Olmsted County, or December 31, 2011 (study end date). We censored follow-up such that each case and matched control had similar periods of observation. We used generalized linear modeling (controlling for age, sex, preexisting conditions, and costs 1 year before index) to predict costs for cases and controls.

Results: Adjusted mean predicted costs were 2.5-fold higher for cases ($62,838) than for controls ($24,464) (P<.001) from index to up to 5 years post index. Cost differences between cases and controls were greatest within the first 3 months after the event date (mean difference=$16,897) but costs remained significantly higher for cases compared with controls for up to 3 years.

Conclusions: VTE during or after recent hospitalization for medical illness contributes a substantial economic burden.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4586032PMC
April 2015

Costs of venous thromboembolism associated with hospitalization for medical illness.

Am J Manag Care 2015 Apr 1;21(4):e255-63. Epub 2015 Apr 1.

Stabile 6-Hematology Research, Mayo Clinic, 200 First St, SW, Rochester, MN 55905. E-mail:

Objectives: To determine population-based estimates of medical costs attributable to venous thromboembolism (VTE) among patients currently or recently hospitalized for acute medical illness.

Study Design: Population-based cohort study conducted in Olmsted County, Minnesota.

Methods: Using Rochester Epidemiology Project (REP) resources, we identified all Olmsted County residents with objectively diagnosed incident VTE during or within 92 days of hospitalization for acute medical illness over the 18-year period of 1988 to 2005 (n=286). One Olmsted County resident hospitalized for medical illness without VTE was matched to each case for event date (±1 year), duration of prior medical history, and active cancer status. Subjects were followed forward in REP provider-linked billing data for standardized, inflation-adjusted direct medical costs (excluding outpatient pharmaceutical costs) from 1 year before their respective event or index date to the earliest of death, emigration from Olmsted County, or December 31, 2011 (study end date). We censored follow-up such that each case and matched control had similar periods of observation. We used generalized linear modeling (controlling for age, sex, preexisting conditions, and costs 1 year before index) to predict costs for cases and controls.

Results: Adjusted mean predicted costs were 2.5-fold higher for cases ($62,838) than for controls ($24,464) (P<.001) from index to up to 5 years post index. Cost differences between cases and controls were greatest within the first 3 months after the event date (mean difference=$16,897) but costs remained significantly higher for cases compared with controls for up to 3 years.

Conclusions: VTE during or after recent hospitalization for medical illness contributes a substantial economic burden.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4586032PMC
April 2015

Direct medical costs and source of cost differences across the spectrum of cognitive decline: a population-based study.

Alzheimers Dement 2015 Aug 6;11(8):917-32. Epub 2015 Apr 6.

Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA; Department of Neurology, Mayo Clinic, Rochester, MN, USA.

Background: Objective cost estimates and source of cost differences are needed across the spectrum of cognition, including cognitively normal (CN), mild cognitive impairment (MCI), newly discovered dementia, and prevalent dementia.

Methods: Subjects were a subset of the Mayo Clinic Study of Aging stratified-random sampling of Olmsted County, MN, residents aged 70 to 89 years. A neurologist reviewed provider-linked medical records to identify prevalent dementia (review date = index). Remaining subjects were invited to participate in prospective clinical/neuropsychological assessments; participants were categorized as CN, MCI, or newly discovered dementia (assessment date = index). Costs for medical services/procedures 1-year pre-index (excluding indirect and long-term care costs) were estimated using line-item provider-linked administrative data. We estimated contributions of care-delivery site and comorbid conditions (including and excluding neuropsychiatric diagnoses) to between-category cost differences.

Results: Annual mean medical costs for CN, MCI, newly discovered dementia, and prevalent dementia were $6042, $6784, $9431, $11,678, respectively. Hospital inpatient costs contributed 70% of total costs for prevalent dementia and accounted for differences between CN and both prevalent and newly discovered dementia. Ambulatory costs accounted for differences between CN and MCI. Age-, sex-, education-adjusted differences reached significance for CN versus newly discovered and prevalent dementia and for MCI versus prevalent dementia. After considering all comorbid diagnoses, between-category differences were reduced (e.g., prevalent dementia minus MCI (from $4842 to $3575); newly discovered dementia minus CN (from $3578 to $711)). Following the exclusion of neuropsychiatric diagnoses from comorbidity adjustment, between-category differences tended to revert to greater differences.

Conclusions: Cost estimates did not differ significantly between CN and MCI. Substantial differences between MCI and prevalent dementia reflected high inpatient costs for dementia and appear partly related to co-occurring mental disorders. Such comparisons can help inform models aimed at identifying where, when, and for which individuals proposed interventions might be cost-effective.
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http://dx.doi.org/10.1016/j.jalz.2015.01.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4543557PMC
August 2015

Direct medical costs attributable to venous thromboembolism among persons hospitalized for major operation: a population-based longitudinal study.

Surgery 2015 Mar 26;157(3):423-31. Epub 2015 Jan 26.

Division of Cardiovascular Diseases and Gonda Vascular Center, Department of Internal Medicine, Mayo Clinic, Rochester, MN; Division of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, MN; Division of Epidemiology, Department of Health Sciences Research, Mayo Clinic, Rochester, MN. Electronic address:

Background: We estimated medical costs attributable to venous thromboembolism (VTE) among patients currently or recently hospitalized for major operation.

Methods: Using Rochester Epidemiology Project resources, we identified all Olmsted County, MN, residents with objectively diagnosed incident VTE within 92 days of hospitalization for major operation during an 18-year period, 1988-2005 (n = 355). One Olmsted County resident hospitalized for major operation without VTE was matched to each case on event date (±1 year), type of operation, duration of previous medical history, and active cancer status. Subjects were followed in Rochester Epidemiology Project provider-linked billing data for standardized, inflation-adjusted direct medical costs from 1 year before index (case's VTE event date and control's matched date) to earliest of death, emigration, or December 31, 2011. We used generalized linear modeling to predict costs for cases and controls and used bootstrapping methods to assess uncertainty and significance of mean adjusted cost differences.

Results: Adjusted mean predicted costs were more than 1.5-fold greater for cases ($55,956) than for controls ($32,718) (P ≤ .001) from index to up to 5 years postindex. Cost differences between cases and controls were greatest within the first 3 months after index (mean difference = $12,381). Costs were greater for cases than controls (mean difference = $10,797) from 3 months to up to 5 years postindex and together accounted for about half of the overall cost difference.

Conclusion: VTE during or after recent hospitalization for major operation contributes a substantial economic burden; VTE-attributable costs are greatest in the initial 3 months but persist for up to 5 years.
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http://dx.doi.org/10.1016/j.surg.2014.10.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4346535PMC
March 2015

Long-term stimulant medication treatment of attention-deficit/hyperactivity disorder: results from a population-based study.

J Dev Behav Pediatr 2014 Sep;35(7):448-57

*Department of Pediatric and Adolescent Medicine, Division of Developmental and Behavioral Pediatrics; †Department of Health Sciences Research, Division of Clinical Epidemiology; ‡Department of Psychiatry and Psychology; and §Department of Health Sciences Research, Division of Biostatistics, Mayo Clinic College of Medicine, Rochester, MN.

The purpose of this study was to offer detailed information about stimulant medication treatment provided throughout childhood to 379 children with research-identified attention-deficit hyperactivity disorder (ADHD) in the 1976-1982 Rochester, MN, birth cohort. Subjects were retrospectively followed from birth until a mean of 17.2 years of age. The complete medical record of each subject was reviewed. The history and results of each episode of stimulant treatment were compared by gender, DSMIV subtype of ADHD, and type of stimulant medication. Overall, 77.8% of subjects were treated with stimulants. Boys were 1.8 times more likely than girls to be treated. The median age at initiation (9.8 years), median duration of treatment (33.8 months), and likelihood of developing at least one side effect (22.3%) were not significantly different by gender. Overall, 73.1% of episodes of stimulant treatment were associated with a favorable response. The likelihood of a favorable response was comparable for boys and girls. Treatment was initiated earlier for children with either ADHD combined type or ADHD hyperactive-impulsive type than for children with ADHD predominantly inattentive type and duration of treatment was longer for ADHD combined type. There was no association between DSM-IV subtype and likelihood of a favorable response or of side effects. Dextroamphetamine and methylphenidate were equally likely to be associated with a favorable response, but dextroamphetamine was more likely to be associated with side effects. These results demonstrate that the effectiveness of stimulant medication treatment of ADHD provided throughout childhood is comparable to the efficacy of stimulant treatment demonstrated in clinical trials.
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http://dx.doi.org/10.1097/DBP.0000000000000099DOI Listing
September 2014

Rethinking guidelines for VTE risk among nursing home residents: a population-based study merging medical record detail with standardized nursing home assessments.

Chest 2014 Aug;146(2):412-421

Department of Health Sciences Research, and the Division of Hematology, Department of Internal Medicine, Mayo Clinic, Rochester, MN; Division of Cardiovascular Disease, Department of Internal Medicine, Mayo Clinic, Rochester, MN.

Background: Nursing home (NH) residents are at increased risk for both VTE and bleeding from pharmacologic prophylaxis. Construction of prophylaxis guidelines is hampered by NH-specific limitations with VTE case identification and characterization of risk. We addressed these limitations by merging detailed provider-linked Rochester Epidemiology Project (REP) medical records with Centers for Medicare and Medicaid Services Minimum Data Set (MDS) NH assessments.

Methods: This population-based nested case-control study identified all Olmsted County, Minnesota, residents with first-lifetime VTE October 1, 1998, through December 31, 2005, while a resident of an NH (N = 91) and one to two age-, sex-, and calendar year-matched NH non-VTE control subjects. For each NH case without hospitalization 3 months before VTE (n = 23), we additionally identified three to four nonhospitalized NH control subjects. REP and MDS records were reviewed before index date (VTE date for cases; respective REP encounter date for control subjects) for numerous characteristics previously associated with VTE in non-NH populations. Data were modeled using conditional logistic regression.

Results: The multivariate model consisting of all cases and control subjects identified only three characteristics independently associated with VTE: respiratory infection vs no infection (OR, 5.9; 95% CI, 2.6-13.1), extensive or total assistance with walking in room (5.6, 2.5-12.6), and general surgery (3.3, 1.0-10.8). In analyses limited to nonhospitalized cases and control subjects, only nonrespiratory infection vs no infection was independently associated with VTE (8.8, 2.7-29.2).

Conclusions: Contrary to previous assumptions, most VTE risk factors identified in non-NH populations do not apply to the NH population. NH residents with infection, substantial mobility limitations, or recent general surgery should be considered potential candidates for VTE prophylaxis.
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http://dx.doi.org/10.1378/chest.13-2652DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4122277PMC
August 2014

Familial risk of epilepsy: a population-based study.

Brain 2014 Mar 26;137(Pt 3):795-805. Epub 2014 Jan 26.

1 Department of Epidemiology, School of Public Health, University of Colorado Denver, Aurora, Colorado 80045, USA.

Almost all previous studies of familial risk of epilepsy have had potentially serious methodological limitations. Our goal was to address these limitations and provide more rigorous estimates of familial risk in a population-based study. We used the unique resources of the Rochester Epidemiology Project to identify all 660 Rochester, Minnesota residents born in 1920 or later with incidence of epilepsy from 1935-94 (probands) and their 2439 first-degree relatives who resided in Olmsted County. We assessed incidence of epilepsy in relatives by comprehensive review of the relatives' medical records, and estimated age-specific cumulative incidence and standardized incidence ratios for epilepsy in relatives compared with the general population, according to proband and relative characteristics. Among relatives of all probands, cumulative incidence of epilepsy to age 40 was 4.7%, and risk was increased 3.3-fold (95% confidence interval 2.75-5.99) compared with population incidence. Risk was increased to the greatest extent in relatives of probands with idiopathic generalized epilepsies (standardized incidence ratio 6.0) and epilepsies associated with intellectual or motor disability presumed present from birth, which we denoted 'prenatal/developmental cause' (standardized incidence ratio 4.3). Among relatives of probands with epilepsy without identified cause (including epilepsies classified as 'idiopathic' or 'unknown cause'), risk was significantly increased for epilepsy of prenatal/developmental cause (standardized incidence ratio 4.1). Similarly, among relatives of probands with prenatal/developmental cause, risk was significantly increased for epilepsies without identified cause (standardized incidence ratio 3.8). In relatives of probands with generalized epilepsy, standardized incidence ratios were 8.3 (95% confidence interval 2.93-15.31) for generalized epilepsy and 2.5 (95% confidence interval 0.92-4.00) for focal epilepsy. In relatives of probands with focal epilepsy, standardized incidence ratios were 1.0 (95% confidence interval 0.00-2.19) for generalized epilepsy and 2.6 (95% confidence interval 1.19-4.26) for focal epilepsy. Epilepsy incidence was greater in offspring of female probands than in offspring of male probands, and this maternal effect was restricted to offspring of probands with focal epilepsy. The results suggest that risks for epilepsies of unknown and prenatal/developmental cause may be influenced by shared genetic mechanisms. They also suggest that some of the genetic influences on generalized and focal epilepsies are distinct. However, the similar increase in risk for focal epilepsy among relatives of probands with either generalized (2.5-fold) or focal epilepsy (2.6-fold) may reflect some coexisting shared genetic influences.
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http://dx.doi.org/10.1093/brain/awt368DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3927702PMC
March 2014

Billing code algorithms to identify cases of peripheral artery disease from administrative data.

J Am Med Inform Assoc 2013 Dec 28;20(e2):e349-54. Epub 2013 Oct 28.

Geriatric Cardiovascular Department, Chinese PLA General Hospital, Beijing, China.

Objective: To construct and validate billing code algorithms for identifying patients with peripheral arterial disease (PAD).

Methods: We extracted all encounters and line item details including PAD-related billing codes at Mayo Clinic Rochester, Minnesota, between July 1, 1997 and June 30, 2008; 22 712 patients evaluated in the vascular laboratory were divided into training and validation sets. Multiple logistic regression analysis was used to create an integer code score from the training dataset, and this was tested in the validation set. We applied a model-based code algorithm to patients evaluated in the vascular laboratory and compared this with a simpler algorithm (presence of at least one of the ICD-9 PAD codes 440.20-440.29). We also applied both algorithms to a community-based sample (n=4420), followed by a manual review.

Results: The logistic regression model performed well in both training and validation datasets (c statistic=0.91). In patients evaluated in the vascular laboratory, the model-based code algorithm provided better negative predictive value. The simpler algorithm was reasonably accurate for identification of PAD status, with lesser sensitivity and greater specificity. In the community-based sample, the sensitivity (38.7% vs 68.0%) of the simpler algorithm was much lower, whereas the specificity (92.0% vs 87.6%) was higher than the model-based algorithm.

Conclusions: A model-based billing code algorithm had reasonable accuracy in identifying PAD cases from the community, and in patients referred to the non-invasive vascular laboratory. The simpler algorithm had reasonable accuracy for identification of PAD in patients referred to the vascular laboratory but was significantly less sensitive in a community-based sample.
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http://dx.doi.org/10.1136/amiajnl-2013-001827DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3861931PMC
December 2013

Long-term survival after traumatic brain injury: a population-based analysis controlled for nonhead trauma.

J Head Trauma Rehabil 2014 Jan-Feb;29(1):E1-8

Department of Physical Medicine and Rehabilitation (Dr Brown), Division of Epidemiology (Dr Leibson), Division of Biomedical Statistics and Informatics (Dr Mandrekar and Ms Ransom), Department of Neurology (Dr Mandrekar), and Department of Psychiatry and Psychology (Dr Malec), Mayo Clinic, Rochester, Minnesota; and Department of Physical Medicine and Rehabilitation, Indiana University School of Medicine and Rehabilitation Hospital of Indiana, Indianapolis (Dr Malec).

Objective: To examine the contribution of co-occurring nonhead injuries to hazard of death after traumatic brain injury (TBI).

Participants: A random sample of Olmsted County, Minnesota, residents with confirmed TBI from 1987 through 1999 was identified.

Design: Each case was assigned an age- and sex-matched, non-TBI "regular control" from the population. For "special cases" with accompanying nonhead injuries, 2 matched "special controls" with nonhead injuries of similar severity were assigned.

Measures: Vital status was followed from baseline (ie, injury date for cases, comparable dates for controls) through 2008. Cases were compared first with regular controls and second with regular or special controls, depending on case type.

Results: In total, 1257 cases were identified (including 221 special cases). For both cases versus regular controls and cases versus regular or special controls, the hazard ratio was increased from baseline to 6 months (10.82 [2.86-40.89] and 7.13 [3.10-16.39], respectively) and from baseline through study end (2.92 [1.74-4.91] and 1.48 [1.09-2.02], respectively). Among 6-month survivors, the hazard ratio was increased for cases versus regular controls (1.43 [1.06-2.15]) but not for cases versus regular or special controls (1.05 [0.80-1.38]).

Conclusions: Among 6-month survivors, accounting for nonhead injuries resulted in a nonsignificant effect of TBI on long-term mortality.
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http://dx.doi.org/10.1097/HTR.0b013e318280d3e6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4321729PMC
September 2014

In reply.

Mayo Clin Proc 2013 Feb;88(2):211-2

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http://dx.doi.org/10.1016/j.mayocp.2012.11.008DOI Listing
February 2013

Asthma and proinflammatory conditions: a population-based retrospective matched cohort study.

Mayo Clin Proc 2012 Oct 12;87(10):953-60. Epub 2012 Sep 12.

Department of Medicine, Harbor Hospital, Baltimore, MD, USA.

Objective: To determine the association between asthma and proinflammatory conditions.

Participants And Methods: This population-based retrospective matched cohort study enrolled all asthmatic patients among Rochester, Minnesota, residents between January 1, 1964, and December 31, 1983. For each asthmatic patient, 2 age-and sex-matched nonasthmatic individuals were drawn from the same population. The asthmatic and nonasthmatic cohorts were followed forward in the Rochester Epidemiology Project diagnostic index for inflammatory bowel disease (IBD), rheumatoid arthritis (RA), diabetes mellitus (DM), and coronary heart disease (CHD) as outcome events. Data were fitted to Cox proportional hazards models.

Results: We identified 2392 asthmatic patients and 4784 nonasthmatic controls. Of the asthmatic patients, 1356 (57%) were male, and mean age at asthma onset was 15.1 years. Incidence rates of IBD, RA, DM, and CHD in nonasthmatic controls were 32.8, 175.9, 132.0, and 389.7 per 100,000 person-years, respectively; those for asthmatic patients were 41.4, 227.9, 282.6, and 563.7 per 100,000 person-years, respectively. Asthma was associated with increased risks of DM (hazard ratio, 2.11; 95% confidence interval, 1.43-3.13; P<.001) and CHD (hazard ratio, 1.47; 95% confidence interval, 1.05-2.06; P=.02) but not with increased risks of IBD or RA.

Conclusion: Although asthma is a helper T cell type 2-predominant condition, it may increase the risks of helper T cell type 1-polarized proinflammatory conditions, such as CHD and DM. Physicians who care for asthmatic patients need to address these unrecognized risks in asthmatic patients.
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http://dx.doi.org/10.1016/j.mayocp.2012.05.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3538394PMC
October 2012

Venous thromboembolism in nursing home residents: role of selected risk factors.

J Am Geriatr Soc 2012 Sep 6;60(9):1718-23. Epub 2012 Aug 6.

Divisions of Epidemiology, Department of Health Sciences Research, Mayo Clinic Rochester, Rochester, Minnesota 55905, USA.

Objectives: To provide nursing home (NH)-specific estimates to assess whether venous thromboembolism (VTE) risk factors identified for the general population apply to NH residents.

Design: Population-based case-control study.

Setting: Olmsted County, Minnesota.

Participants: All county residents with symptomatic objectively diagnosed incident VTE while resident in a NH from 1988 through 2000 (N = 182) and two age-, sex-, calendar-year-matched non-VTE Olmsted County NH residents per case (N = 364).

Measurements: Provider-linked medical records were reviewed to obtain information on active malignancy and recent hospitalization, surgery, trauma, or fracture as of index date (case's VTE date; respective provider registration date for controls). Risk factor prevalence and VTE-associated odds ratios (OR) were estimated and compared with previously obtained data for all Olmsted County residents from 1988 through 2000. For analyses, both groups were limited to individuals aged 65 and older.

Results: In NH residents, active malignancy, recent hospitalization, and recent surgery significantly increased VTE risk, but the magnitude of risk appeared much lower than general population estimates (e.g., for major surgery, OR = 2.5, 95% confidence interval (CI) = 1.4-4.3 for NH residents vs OR = 11, 95% CI = 7.0-17 for general population). In general, the prevalence of all evaluated VTE risk factors appeared much higher in NH controls than in general population controls. Thromboprophylaxis rates appeared higher for NH cases and controls than in the general population; disconcertingly, 47% of NH cases received prophylaxis.

Conclusion: Although general population VTE risk factors (active cancer and recent hospitalization or surgery) can identify NH residents at higher risk for VTE, these exposures do not adequately stratify VTE risk for thromboprophylaxis recommendations. Further research into NH-specific risk factors and prophylaxis effectiveness is required.
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http://dx.doi.org/10.1111/j.1532-5415.2012.04100.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3445699PMC
September 2012

The absence of longitudinal data limits the accuracy of high-throughput clinical phenotyping for identifying type 2 diabetes mellitus subjects.

Int J Med Inform 2013 Apr 2;82(4):239-47. Epub 2012 Jul 2.

Institute for Health Informatics, University of Minnesota, Twin Cities, MN, USA.

Purpose: To evaluate the impact of insufficient longitudinal data on the accuracy of a high-throughput clinical phenotyping (HTCP) algorithm for identifying (1) patients with type 2 diabetes mellitus (T2DM) and (2) patients with no diabetes.

Methods: Retrospective study conducted at Mayo Clinic in Rochester, Minnesota. Eligible subjects were Olmsted County residents with ≥1 Mayo Clinic encounter in each of three time periods: (1) 2007, (2) from 1997 through 2006, and (3) before 1997 (N = 54,283). Diabetes relevant electronic medical record (EMR) data about diagnoses, laboratories, and medications were used. We employed the HTCP algorithm to categorize individuals as T2DM cases and non-diabetes controls. Considering the full 11 years (1997-2007) as the gold standard, we compared gold-standard categorizations with those using data for 10 subsequent intervals, ranging from 1998-2007 (10-year data) to 2007 (1-year data). Positive predictive values (PPVs) and false-negative rates (FNRs) were calculated. McNemar tests were used to determine whether categorizations using shorter time periods differed from the gold standard. Statistical significance was defined as P < 0.05.

Results: We identified 2770 T2DM cases and 21,005 controls when the algorithm was applied using 11-year data. Using 2007 data alone, PPVs and FNRs, respectively, were 70% and 25% for case identification and 59% and 67% for control identification. All time frames differed significantly from the gold standard, except for the 10-year period.

Conclusions: The accuracy of the algorithm reduced remarkably as data were limited to shorter observation periods. This impact should be considered carefully when designing/executing HTCP algorithms.
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http://dx.doi.org/10.1016/j.ijmedinf.2012.05.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3478423PMC
April 2013

Medical care costs associated with traumatic brain injury over the full spectrum of disease: a controlled population-based study.

J Neurotrauma 2012 Jul 26;29(11):2038-49. Epub 2012 Apr 26.

Department of Health Sciences Research, Division of Epidemiology, Mayo Clinic, 200 First Street, S.W. Rochester, MN 55905, USA.

Data on traumatic brain injury (TBI) economic outcomes are limited. We used Rochester Epidemiology Project (REP) resources to estimate long-term medical costs for clinically-confirmed incident TBI across the full range of severity after controlling for pre-existing conditions and co-occurring injuries. All Olmsted County, Minnesota, residents with diagnoses indicative of potential TBI from 1985-2000 (n=46,114) were identified, and a random sample (n=7175) was selected for medical record review to confirm case status, and to characterize as definite (moderate/severe), probable (mild), or possible (symptomatic) TBI. For each case, we identified one age- and sex-matched non-TBI control registered in REP in the same year (±1 year) as case's TBI. Cases with co-occurring non-head injuries were assessed for non-head-injury severity and assigned similar non-head-injury-severity controls. The 1145 case/control pairs for 1988-2000 were followed until earliest death/emigration of either member for medical costs 12 months before and up to 6 years after baseline (i.e., injury date for cases and comparable dates for controls). Differences between case and control costs were stratified by TBI severity, as defined by evidence of brain injury; comparisons used Wilcoxon signed-rank plus multivariate modeling (adjusted for pre-baseline characteristics). From baseline until 6 years, each TBI category exhibited significant incremental costs. For definite and probable TBI, most incremental costs occurred within the first 6 months; significant long-term incremental medical costs were not apparent among 1-year survivors. By contrast, cost differences between possible TBI cases and controls were not as great within the first 6 months, but were substantial among 1-year survivors. Although mean incremental costs were highest for definite cases, probable and possible cases accounted for>90% of all TBI events and 66% of total incremental costs. Preventing probable and possible events might facilitate substantial reductions in TBI-associated medical care costs.
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http://dx.doi.org/10.1089/neu.2010.1713DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3408240PMC
July 2012

Generalizability of epidemiological findings and public health decisions: an illustration from the Rochester Epidemiology Project.

Mayo Clin Proc 2012 Feb;87(2):151-60

Division of Epidemiology, Mayo Clinic, Rochester, MN, USA.

Objective: To illustrate the problem of generalizability of epidemiological findings derived from a single population using data from the Rochester Epidemiology Project and from the US Census.

Methods: We compared the characteristics of the Olmsted County, Minnesota, population with the characteristics of populations residing in the state of Minnesota, the Upper Midwest, and the entire United States.

Results: Age, sex, and ethnic characteristics of Olmsted County were similar to those of the state of Minnesota and the Upper Midwest from 1970 to 2000. However, Olmsted County was less ethnically diverse than the entire US population (90.3% vs 75.1% white), more highly educated (91.1% vs 80.4% high school graduates), and wealthier ($51,316 vs $41,994 median household income; 2000 US Census data). Age- and sex-specific mortality rates were similar for Olmsted County, the state of Minnesota, and the entire United States.

Conclusion: We provide an example of analyses and comparisons that may guide the generalization of epidemiological findings from a single population to other populations or to the entire United States.
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http://dx.doi.org/10.1016/j.mayocp.2011.11.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3538404PMC
February 2012

Survival in patients with poorly compressible leg arteries.

J Am Coll Cardiol 2012 Jan;59(4):400-7

Division of Cardiovascular Diseases and the Gonda Vascular Center, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.

Objectives: This study sought to compare survival of patients with poorly compressible arteries (PCA) to those with a normal ankle-brachial index (ABI) and those with peripheral arterial disease (PAD).

Background: Limited data are available regarding survival in patients with PCA identified in the clinical setting by noninvasive lower extremity arterial evaluation.

Methods: We conducted a historical cohort study of consecutive patients who underwent outpatient, noninvasive lower extremity arterial evaluation at the Mayo Clinic, Rochester, Minnesota, from January 1998 through December 2007, and who were followed for a mean duration of 5.8 ± 3.1 years. An ABI 1.00 to 1.30 was considered normal, PAD was defined as a resting or post-exercise ABI ≤0.90, and PCA defined as an ABI ≥1.4 and/or an ankle systolic blood pressure >255 mm Hg. Patients were followed for all-cause mortality through September 30, 2009.

Results: Of 16,493 individuals (mean age 67.8 ± 13.0 years, 59% male); 29% had normal ABI, 54% had PAD, and 17% had PCA. During follow-up (mean duration 5.8 ± 3.1 years), 4,365 patients (26%) died. The percent alive at the end of the study period was 88%, 70%, and 60% for normal ABI, PAD, and PCA, respectively. After adjustment for age, sex, cardiovascular risk factors, comorbid conditions, and medication use, the hazard ratios (95% confidence intervals) of death associated with PCA were 2.0 (1.8 to 2.2) and 1.3 (1.2 to 1.4) compared with the normal ABI and PAD groups, respectively.

Conclusions: Patients identified by noninvasive vascular testing to have poorly compressible leg arteries have poor survival, worse than those with a normal ABI or those with PAD.
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http://dx.doi.org/10.1016/j.jacc.2011.09.055DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3307094PMC
January 2012

Impact of data fragmentation across healthcare centers on the accuracy of a high-throughput clinical phenotyping algorithm for specifying subjects with type 2 diabetes mellitus.

J Am Med Inform Assoc 2012 Mar-Apr;19(2):219-24. Epub 2012 Jan 16.

Institute for Health Informatics, University of Minnesota, Twin Cities, Minnesota, USA.

Objective: To evaluate data fragmentation across healthcare centers with regard to the accuracy of a high-throughput clinical phenotyping (HTCP) algorithm developed to differentiate (1) patients with type 2 diabetes mellitus (T2DM) and (2) patients with no diabetes.

Materials And Methods: This population-based study identified all Olmsted County, Minnesota residents in 2007. We used provider-linked electronic medical record data from the two healthcare centers that provide >95% of all care to County residents (ie, Olmsted Medical Center and Mayo Clinic in Rochester, Minnesota, USA). Subjects were limited to residents with one or more encounter January 1, 2006 through December 31, 2007 at both healthcare centers. DM-relevant data on diagnoses, laboratory results, and medication from both centers were obtained during this period. The algorithm was first executed using data from both centers (ie, the gold standard) and then from Mayo Clinic alone. Positive predictive values and false-negative rates were calculated, and the McNemar test was used to compare categorization when data from the Mayo Clinic alone were used with the gold standard. Age and sex were compared between true-positive and false-negative subjects with T2DM. Statistical significance was accepted as p<0.05.

Results: With data from both medical centers, 765 subjects with T2DM (4256 non-DM subjects) were identified. When single-center data were used, 252 T2DM subjects (1573 non-DM subjects) were missed; an additional false-positive 27 T2DM subjects (215 non-DM subjects) were identified. The positive predictive values and false-negative rates were 95.0% (513/540) and 32.9% (252/765), respectively, for T2DM subjects and 92.6% (2683/2898) and 37.0% (1573/4256), respectively, for non-DM subjects. Age and sex distribution differed between true-positive (mean age 62.1; 45% female) and false-negative (mean age 65.0; 56.0% female) T2DM subjects.

Conclusion: The findings show that application of an HTCP algorithm using data from a single medical center contributes to misclassification. These findings should be considered carefully by researchers when developing and executing HTCP algorithms.
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http://dx.doi.org/10.1136/amiajnl-2011-000597DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3277630PMC
May 2012

Use of diverse electronic medical record systems to identify genetic risk for type 2 diabetes within a genome-wide association study.

J Am Med Inform Assoc 2012 Mar-Apr;19(2):212-8. Epub 2011 Nov 19.

Northwestern University, Chicago, Illinois, USA.

Objective: Genome-wide association studies (GWAS) require high specificity and large numbers of subjects to identify genotype-phenotype correlations accurately. The aim of this study was to identify type 2 diabetes (T2D) cases and controls for a GWAS, using data captured through routine clinical care across five institutions using different electronic medical record (EMR) systems.

Materials And Methods: An algorithm was developed to identify T2D cases and controls based on a combination of diagnoses, medications, and laboratory results. The performance of the algorithm was validated at three of the five participating institutions compared against clinician review. A GWAS was subsequently performed using cases and controls identified by the algorithm, with samples pooled across all five institutions.

Results: The algorithm achieved 98% and 100% positive predictive values for the identification of diabetic cases and controls, respectively, as compared against clinician review. By standardizing and applying the algorithm across institutions, 3353 cases and 3352 controls were identified. Subsequent GWAS using data from five institutions replicated the TCF7L2 gene variant (rs7903146) previously associated with T2D.

Discussion: By applying stringent criteria to EMR data collected through routine clinical care, cases and controls for a GWAS were identified that subsequently replicated a known genetic variant. The use of standard terminologies to define data elements enabled pooling of subjects and data across five different institutions to achieve the robust numbers required for GWAS.

Conclusions: An algorithm using commonly available data from five different EMR can accurately identify T2D cases and controls for genetic study across multiple institutions.
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http://dx.doi.org/10.1136/amiajnl-2011-000439DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3277617PMC
May 2012

Incidence of traumatic brain injury across the full disease spectrum: a population-based medical record review study.

Epidemiology 2011 Nov;22(6):836-44

Division of Epidemiology, Department of Health Sciences Research, Mayo Clinic, Rochester, MN 55905, USA.

Background: Extremely few objective estimates of traumatic brain injury incidence include all ages, both sexes, all injury mechanisms, and the full spectrum from very mild to fatal events.

Methods: We used unique Rochester Epidemiology Project medical records-linkage resources, including highly sensitive and specific diagnostic coding, to identify all Olmsted County, MN, residents with diagnoses suggestive of traumatic brain injury regardless of age, setting, insurance, or injury mechanism. Provider-linked medical records for a 16% random sample were reviewed for confirmation as definite, probable, possible (symptomatic), or no traumatic brain injury. We estimated incidence per 100,000 person-years for 1987-2000 and compared these record-review rates with rates obtained using Centers for Disease Control and Prevention (CDC) data-systems approach. For the latter, we identified all Olmsted County residents with any CDC-specified diagnosis codes recorded on hospital/emergency department administrative claims or death certificates during 1987-2000.

Results: Of sampled individuals, 1257 met record-review criteria for incident traumatic brain injury; 56% were ages 16-64 years, 56% were male, and 53% were symptomatic. Mechanism, sex, and diagnostic certainty differed by age. The incidence rate per 100,000 person-years was 558 (95% confidence interval = 528-590) versus 341 (331-350) using the CDC data-system approach. The CDC approach captured only 40% of record-review cases. Seventy-four percent of missing cases presented to the hospital/emergency department; none had CDC-specified codes assigned on hospital/emergency department administrative claims or death certificates; and 66% were symptomatic.

Conclusions: Capture of symptomatic traumatic brain injuries requires a wider range of diagnosis codes, plus sampling strategies to avoid high rates of false-positive events.
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http://dx.doi.org/10.1097/EDE.0b013e318231d535DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3345264PMC
November 2011

Nurse staffing and inpatient hospital mortality.

N Engl J Med 2011 Mar;364(11):1037-45

Department of Health Services, University of California, Los Angeles, School of Public Health, Los Angeles, USA.

Background: Cross-sectional studies of hospital-level administrative data have shown an association between lower levels of staffing of registered nurses (RNs) and increased patient mortality. However, such studies have been criticized because they have not shown a direct link between the level of staffing and individual patient experiences and have not included sufficient statistical controls.

Methods: We used data from a large tertiary academic medical center involving 197,961 admissions and 176,696 nursing shifts of 8 hours each in 43 hospital units to examine the association between mortality and patient exposure to nursing shifts during which staffing by RNs was 8 hours or more below the staffing target. We also examined the association between mortality and high patient turnover owing to admissions, transfers, and discharges. We used Cox proportional-hazards models in the analyses with adjustment for characteristics of patients and hospital units.

Results: Staffing by RNs was within 8 hours of the target level for 84% of shifts, and patient turnover was within 1 SD of the day-shift mean for 93% of shifts. Overall mortality was 61% of the expected rate for similar patients on the basis of modified diagnosis-related groups. There was a significant association between increased mortality and increased exposure to unit shifts during which staffing by RNs was 8 hours or more below the target level (hazard ratio per shift 8 hours or more below target, 1.02; 95% confidence interval [CI], 1.01 to 1.03; P<0.001). The association between increased mortality and high patient turnover was also significant (hazard ratio per high-turnover shift, 1.04; 95% CI, 1.02 to 1.06; P<0.001).

Conclusions: In this retrospective observational study, staffing of RNs below target levels was associated with increased mortality, which reinforces the need to match staffing with patients' needs for nursing care. (Funded by the Agency for Healthcare Research and Quality.).
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http://dx.doi.org/10.1056/NEJMsa1001025DOI Listing
March 2011

A survey of very-long-term outcomes after traumatic brain injury among members of a population-based incident cohort.

J Neurotrauma 2011 Feb 5;28(2):167-76. Epub 2011 Feb 5.

Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, Minnesota 55905, USA.

To assess quality of life and barriers to participation in vocational and community life for persons with traumatic brain injury (TBI) over the very-long term, a population-based cohort was identified in Olmsted County, Minnesota; 1623 individuals were identified as having experienced a confirmed TBI while a resident of Olmsted County, Minnesota, during the period from 1935-2000. A survey was sent to eligible individuals that included elements of standardized instruments addressing health status and disability, and questions that assessed issues important to successful social reintegration after TBI. Of 1623 eligible participants sent surveys, 605 responded (37% response rate). Thirty-nine percent of respondents were female and 79% had mild injuries. Mean age at injury was 30.8 years, and mean years since injury was 28.8. Overall, respondents reported living in the community; the majority were married and had achieved education beyond high school. Problems with memory, thinking, and physical and emotional health were most often reported. Respondents reported low levels of depression and anxiety, and high levels of satisfaction with life. Seventy-three percent of respondents reported no problems that they attributed to their TBI. Increasing injury severity was associated with a significant risk of reporting injury-related problems at survey completion. Respondents with a longer time since injury were less likely to report any TBI-related problems. These results indicate that self-reported outcomes and adaptation to impairment-related limitations improve as the time since injury increases. These findings highlight the importance of providing coordinated medical rehabilitation and community-based support services to promote positive outcomes over the life span after TBI.
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http://dx.doi.org/10.1089/neu.2010.1400DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3064530PMC
February 2011

Is progestin an independent risk factor for incident venous thromboembolism? A population-based case-control study.

Thromb Res 2010 Nov 15;126(5):373-8. Epub 2010 Sep 15.

Division of Cardiovascular Disease, Department of Internal Medicine, College of Medicine, Mayo Clinic, Rochester, MN 55905, USA.

Introduction: Because the risk of venous thromboembolism (VTE) associated with progestin is uncertain, we tested oral contraceptives, estrogen and progestin as independent VTE risk factors.

Materials And Methods: Using longitudinal, population-based Rochester Epidemiology Project resources, we identified all Olmsted County, MN women with objectively-diagnosed incident VTE over the 13-year period, 1988-2000 (n=726) and one to two Olmsted County women per case matched on age, event year and duration of prior medical history (n=830), and reviewed their complete medical history in the community for previously-identified VTE risk factors (i.e., hospitalization with or without surgery, nursing home confinement, trauma/fracture, leg paresis, active cancer, varicose veins and pregnancy/postpartum), and oral contraceptive, oral estrogen, and oral or injectable progestin exposure. Using conditional logistic regression we tested these hormone exposures as VTE risk factors, both unadjusted and after adjusting for previously-identified VTE risk factors.

Results: In unadjusted models, oral contraceptives, progestin alone, and estrogen plus progestin were significantly associated with VTE. Individually adjusting for body mass index (BMI) and previously-identified VTE risk factors, these effects remained essentially unchanged except that progestin alone was not associated with VTE after adjusting for active cancer. Considering only case-control pairs without active cancer, progestin alone was positively but non-significantly associated with VTE (OR=2.49; p=0.16). Adjusting for BMI and previously-identified VTE risk factors including active cancer, oral contraceptives, estrogen alone, and progestin with or without estrogen were significantly associated with VTE.

Conclusions: Oral contraceptives, estrogen alone, estrogen plus progestin, and progestin with or without estrogen are independent VTE risk factors.
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http://dx.doi.org/10.1016/j.thromres.2010.08.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2975753PMC
November 2010

Validation of a brief screening instrument for the ascertainment of epilepsy.

Epilepsia 2010 Feb 19;51(2):191-7. Epub 2009 Aug 19.

G.H. Sergievsky Center and Department of Neurology, College of Physicians and Surgeons, Mailman School of Public Health, Columbia University, New York, New York 10032, USA.

Purpose: To validate a brief screening instrument for identifying people with epilepsy in epidemiologic or genetic studies.

Methods: We designed a nine-question screening instrument for epilepsy and administered it by telephone to individuals with medical record-documented epilepsy (lifetime history of >or=2 unprovoked seizures, n = 168) or isolated unprovoked seizure (n = 54), and individuals who were seizure-free on medical record review (n = 120), from a population-based study using Rochester Epidemiology Project resources. Interviewers were blinded to record-review findings.

Results: Sensitivity (the proportion of individuals who screened positive among affected individuals) was 96% for epilepsy and 87% for isolated unprovoked seizure. The false positive rate (FPR, the proportion who screened positive among seizure-free individuals) was 7%. The estimated positive predictive value (PPV) for epilepsy was 23%, assuming a lifetime prevalence of 2% in the population. Use of only a single question asking whether the subject had ever had epilepsy or a seizure disorder resulted in sensitivity 76%, FPR 0.8%, and estimated PPV 66%. Subjects with epilepsy were more likely to screen positive with this question if they were diagnosed after 1964 or continued to have seizures for at least 5 years after diagnosis.

Discussion: Given its high sensitivity, our instrument may be useful for the first stage of screening for epilepsy; however, the PPV of 23% suggests that only about one in four screen-positive individuals will be truly affected. Screening with a single question asking about epilepsy yields a higher PPV but lower sensitivity, and screen-positive subjects may be biased toward more severe epilepsy.
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http://dx.doi.org/10.1111/j.1528-1167.2009.02274.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2844922PMC
February 2010
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