Publications by authors named "David A Ludwig"

40 Publications

Assessing the link between modified 'Teach Back' method and improvement in knowledge of the medical regimen among youth with kidney transplants: The application of digital media.

Patient Educ Couns 2019 05 12;102(5):1035-1039. Epub 2018 Dec 12.

Department of Pediatrics, Division of Pediatric Psychology, University of Miami Miller School of Medicine, Miami, FL, USA.

Objective: The objective of this study was to facilitate functional health literacy (FHL) with a modified "Teach Back" method. A computer-based program was developed for adolescent and young adult kidney transplant recipients (KTR) to knowledgeably answer questions about their medical condition, medications, and create a simple synopsis of their personal health record with the help of the heath care provider (HCP).

Methods: In a pre-post quasi-experimental design, 16 patients received the computer intervention in which they navigated questionnaires and brief informational video clips. Knowledge scores were assessed at baseline and 3 months. The binomial sign test was used to evaluate change in knowledge and purpose of medications.

Results: Mean age was 17.3 ± 2.4 years and 94% were non-Caucasian. Seven of 16 patients were academically below grade level. Twelve of 16 patients improved their overall knowledge (P = 0.0002) and purpose of medications (P = 0.0017).

Conclusions: A Modified "Teach Back" during clinic visits was associated with improvements in FHL.

Practice Implications: This modified 'teach back' program has the potential to improve FHL which could contribute to long-term preservation of kidney transplants.
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http://dx.doi.org/10.1016/j.pec.2018.12.007DOI Listing
May 2019

Predicting Viral Failure in Human Immunodeficiency Virus Perinatally Infected Youth With Persistent Low-Level Viremia on Highly Active Antiretroviral Therapy.

J Pediatric Infect Dis Soc 2019 Sep;8(4):303-309

Department of Pediatrics, Division of Infectious Disease and Immunology, Florida.

Background: Less than optimal adherence with antiretroviral therapy occurs commonly among human immunodeficiency virus HIV)-infected youth. In this study, our object was to identify patterns in the prefailure measurement of viral load (VL) that can reliably predict virological failure (VF) in HIV perinatally infected youth on highly active antiretroviral therapy (HAART).

Methods: We conducted a retrospective chart review of HIV-infected youth with low-level viremia (LLV), defined as an HIV VL between the lower limits of detection (20-75 copies/mL) and 1000 copies/mL. All patients were perinatally infected, under 22 years of age, observed for at least 24 months of consecutive follow-up between May 2008 and July 2014, and received their HIV care at the University of Miami Miller School of Medicine. Of the 349 subjects screened, 100 were eligible for analysis. Virological failure was defined as 3 or more consecutive VLs greater than 1000 copies/mL. Multiple logistic regression and receiver operator characteristic curves were used to identify patterns in VL that ultimately resulted in VF.

Results: Fifteen of the 100 patients experienced VF. Higher log10 mean VL, positive slope of the VL (log10 copies/mL per day), and fewer clinic visits were associated with a higher probability of VF. Sensitivity and specificity were .87 and .95, respectively. Resistance was not found in 12 of 15 patients with VF.

Conclusions: Patients with LLV that had fewer clinic visits and a trend toward increasing VLs had an increased risk of VF. Noncompliance seems to be a major component of VF. Physicians should emphasize the critical nature of medication adherence.
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http://dx.doi.org/10.1093/jpids/piy041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7568520PMC
September 2019

Children's Physical Activity And Health.

Authors:
David A Ludwig

Health Aff (Millwood) 2017 08;36(8):1518

University of Miami Miami, Florida.

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http://dx.doi.org/10.1377/hlthaff.2017.0801DOI Listing
August 2017

Geographic Information Systems to Assess External Validity in Randomized Trials.

Am J Prev Med 2017 Aug 23;53(2):252-259. Epub 2017 Feb 23.

Department of Epidemiology and Prevention, Division of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina; Maya Angelou Center for Health Equity, Wake Forest School of Medicine, Winston-Salem, North Carolina.

Introduction: To support claims that RCTs can reduce health disparities (i.e., are translational), it is imperative that methodologies exist to evaluate the tenability of external validity in RCTs when probabilistic sampling of participants is not employed. Typically, attempts at establishing post hoc external validity are limited to a few comparisons across convenience variables, which must be available in both sample and population. A Type 2 diabetes RCT was used as an example of a method that uses a geographic information system to assess external validity in the absence of a priori probabilistic community-wide diabetes risk sampling strategy.

Methods: A geographic information system, 2009-2013 county death certificate records, and 2013-2014 electronic medical records were used to identify community-wide diabetes prevalence. Color-coded diabetes density maps provided visual representation of these densities. Chi-square goodness of fit statistic/analysis tested the degree to which distribution of RCT participants varied across density classes compared to what would be expected, given simple random sampling of the county population. Analyses were conducted in 2016.

Results: Diabetes prevalence areas as represented by death certificate and electronic medical records were distributed similarly. The simple random sample model was not a good fit for death certificate record (chi-square, 17.63; p=0.0001) and electronic medical record data (chi-square, 28.92; p<0.0001). Generally, RCT participants were oversampled in high-diabetes density areas.

Conclusions: Location is a highly reliable "principal variable" associated with health disparities. It serves as a directly measurable proxy for high-risk underserved communities, thus offering an effective and practical approach for examining external validity of RCTs.
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http://dx.doi.org/10.1016/j.amepre.2017.01.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5985667PMC
August 2017

A multicenter study of diet quality on birth weight and gestational age in infants of HIV-infected women.

Matern Child Nutr 2017 10 8;13(4). Epub 2016 Nov 8.

Division of Pediatric Clinical Research, Department of Pediatrics, Leonard M. Miller School of Medicine, University of Miami, Miami, Florida, USA.

We determined factors associated with diet quality and assessed the relationship between diet quality, birth weight, and gestational age in a prospective national multicenter cohort study. We evaluated diet quality with the Healthy Eating Index (HEI, scale 0-100) in the third trimester of pregnancy with three 24-hr multiple-pass dietary recalls in 266 HIV+ women enrolled in the Pediatric HIV/AIDS Cohort Study. Covariates included demographics, food security, pre-pregnancy body mass index, HIV disease severity, substance use, and antiretroviral exposures. A two-stage multivariate process using classification and regression trees (CART) followed by multiple regression described HEI tendencies, controlled possible confounding effects, and examined the association of HEI with birth weight and gestational age. To assess the stability of the CART solution, both the HEI 2005 and 2010 were evaluated. The mean HEI scores were 56.1 and 47.5 for the 2005 and 2010 HEI, respectively. The first-stage CART analysis examined the relationship between HEI and covariates. Non-US born versus US-born mothers had higher HEI scores (15-point difference, R  = 0.28). There was a secondary partition due to alcohol/cigarette/illicit drug usage (3.5-point difference, R  = 0.03) among US-born women. For the second-stage CART adjusted multiple regression, birth weight z-score was positively related to HEI 2005 and 2010 (partial r's > 0.13, P's ≤ 0.0398), but not gestational age (r = 0.00). We conclude that diet quality among HIV+ women is associated with higher birth weight. Despite the influence of a large cultural effect and poor prenatal behaviors, interventions to improve diet in HIV+ women may help to increase birth weight.
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http://dx.doi.org/10.1111/mcn.12378DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5575978PMC
October 2017

Prenatal Cocaine Exposure and Cardiometabolic Disease Risk Factors in 18- to 20-Year-Old African Americans.

Ethn Dis 2015 Nov 5;25(4):419-26. Epub 2015 Nov 5.

3. Division of Neonatology, Department of Pediatrics, University of Miami Leonard M. Miller School of Medicine.

Objective: The long-term effects of prenatal cocaine exposure (PCE) on physical health are largely unknown. No human studies support or refute a relationship between PCE and the long-term risk for cardiovascular and/or metabolic disease. We investigated the association of PCE on primary cardiometabolic disease risk factors in African Americans (AA) aged 18 to 20 years.

Design: Cohort, longitudinal, prospective.

Setting: Miami-Dade County, Florida, and the University of Miami Miller School of Medicine/Jackson Memorial Medical Center.

Participants: Healthy full-term inner-city AA adolescents (aged 18 to 20 years, n=350) previously enrolled at birth from 1990-1993.

Main Outcome Measures: Fasting serum insulin, glucose, lipids, and high-sensitivity C-reactive protein; systolic and diastolic blood pressures; and the components and prevalence of the metabolic syndrome.

Results: There were no PCE-associated differences in cardiometabolic disease risk factors including the metabolic syndrome and its individual components in AAs aged 18 to 20 years.

Conclusions: The results of our study do not support an association between PCE and increased cardiometabolic disease risk in AAs aged 18 to 20 years. Whether PCE is associated with cardiovascular or metabolic disease in adulthood would require further investigation.
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http://dx.doi.org/10.18865/ed.25.4.419DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4671437PMC
November 2015

Participation Rates and Perceptions of Caregiving Youth Providing Home Health Care.

J Community Health 2016 Apr;41(2):326-33

University of Miami Miller School of Medicine Regional Medical Campus, 2500 N. Military Trail, Suite 260, Boca Raton, FL, 33431, USA.

Little is known about the population of caregiving youth in the United States. We sought to describe the participation rates, demographics, and caregiving tasks among sixth graders served by the American Association of Caregiving Youth (AACY) in its Caregiving Youth Project (CYP) in Palm Beach County, FL and evaluate the perceived benefit of AACY services. Sixth grade enrollment data from eight middle schools between 2007 and 2013 were obtained from The School District of Palm Beach County and the AACY. Data were obtained using a retrospective review of AACY program participant files. These files contained responses to evaluative questions from both students and family members. Overall, 2.2 % of sixth graders enrolled and participated in the program. Among the 396 caregiving sixth graders studied, care recipients were predominantly a grandparent (40.6 %) or parent (30.5 %). Common activities included providing company for the care recipient (85.6 %), emotional support (74.5 %), and assistance with mobility (46.7 %). Youth reported a median of 2.5 h caregiving on weekdays and 4 h on weekend days, while families reported fewer hours (1.6 and 2.3, respectively). At the end of the school year, the sixth graders reported improvement in school (85.5 %), caregiving knowledge (88.5 %), and self-esteem (89.5 %). Slightly over 2 % of sixth graders participated in the CYP. While support services may mitigate the negative effects of the time spent by caregiving youth, more prospective research is needed to better define the true prevalence, tasks, and time spent caregiving among this subpopulation.
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http://dx.doi.org/10.1007/s10900-015-0100-7DOI Listing
April 2016

Correlates of adiponectin in hepatitis C-infected children: the importance of body mass index.

J Pediatr Gastroenterol Nutr 2015 Feb;60(2):165-70

*Department of Pediatrics, Batchelor Children's Research Institute, University of Miami Miller School of Medicine, Miami, FL †Division of Gastroenterology, Boston Children's Hospital ‡Gastrointestinal Unit, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA §Division of Pediatric Gastroenterology, Hepatology, and Nutrition, University of Florida College of Medicine, Gainesville, FL ||Armed Forces Institute of Pathology, Washington, DC.

Objectives: Adiponectin is a regulator of cytokines that, in turn, play a vital role in inflammatory and immune responses. Adiponectin is therefore likely to have a contributory role in hepatitis C virus (HCV) infection. We sought to characterize adiponectin levels and examine correlates in a pediatric HCV-infected cohort.

Methods: We performed a cross-sectional study in children (5-17 years of age, n = 86) in the Pediatric Study of Hepatitis C (PEDS-C) trial. Adiponectin levels were univariately correlated with patient demographics, anthropometrics, and viral and histological measures. Multivariate regression models were used to identify the unique (ie, nonconfounded) associations with adiponectin concentrations.

Results: Body mass index (BMI) had the highest univariate inverse correlation with log(e) adiponectin (r = -0.5, P < 0.0001). In multivariate analysis, BMI remained inversely correlated with log(e) adiponectin after accounting for age and route of HCV transmission (r = -0.38, P = 0.0003). Steatosis and fibrosis were inversely related to log(e) adiponectin in univariate analysis, but these associations were not statistically significant after multivariate adjustments (P ≥ 0.1827).

Conclusions: High BMI among HCV-infected children is associated with lower adiponectin levels. Practitioners should be cognizant of the possible risks of low adiponectin when managing HCV-infected children who are overweight. Further studies are indicated to determine the impact of having low adiponectin on HCV infection in youth.
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http://dx.doi.org/10.1097/MPG.0000000000000604DOI Listing
February 2015

A high school-based voluntary cardiovascular risk screening program: issues of feasibility and correlates of electrocardiographic outcomes.

Pediatr Cardiol 2013 Oct 17;34(7):1612-9. Epub 2013 Mar 17.

All Children's Hospital Heart Institute, St. Petersburg, FL, USA.

Risk factors for adult cardiovascular events can be identified from the prenatal period through childhood. We performed a cardiovascular risk-screening program in students from grades 9-12 in 7 high schools in Hillsborough County, FL. We obtained blood pressure (BP) measurements and calculated body mass index (BMI) as risk factors for future cardiovascular events as well as obtained an electrocardiogram (ECG) for the purposes of detecting possible life-threatening arrhythmias. Of ~14,000 students contacted, 600 (4 %) participated in the screening. Of these, 517 (86 %) were diagnosed with normal, 71 (12 %) with borderline, and 12 (1 %) with abnormal ECGs. Although no participant had any cardiac history, two of the abnormal ECGs indicated a cardiac diagnosis associated with the potential for sudden cardiac death. Both systolic and diastolic BP increased as the ECG diagnosis moved from normal (115.6/73.8) through borderline (121.0/75.9) to an abnormal (125.0/80.7) diagnosis (all P ≤ .0016). An increase in BMI was only observed when an ECG diagnosis was abnormal (P = .0180). Boys had a greater prevalence (18.97 %) of borderline or abnormal ECGs compared with girls (6.75 %), whereas no discernible differences were seen in ECG diagnosis between white and nonwhite individuals (15.09 and 12.26 %, respectively). Although participation rates were low, a high school-based cardiovascular risk-screening program including ECG is feasible. Although ECG diagnosis tended to be related to other known cardiovascular risk factors (BP, BMI), the utility of an abnormal ECG in adolescence as a predictor of future cardiovascular risk will require further evaluation in more controlled settings.
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http://dx.doi.org/10.1007/s00246-013-0682-8DOI Listing
October 2013

Growth and body composition of uninfected children exposed to human immunodeficiency virus: comparison with a contemporary cohort and United States National Standards.

J Pediatr 2013 Jul 26;163(1):249-54.e1-2. Epub 2013 Jan 26.

Division of Pediatric Clinical Research, Department of Pediatrics, Miller School of Medicine, University of Miami, Miami, FL 33101, USA.

Objective: To compare growth and body composition of uninfected children exposed to HIV with a contemporary HIV-unexposed group and to US references.

Study Design: Uninfected children exposed to HIV under 2 years were enrolled into a longitudinal observational study and unexposed children under 2 years of age in a cross-sectional evaluation. Weights, lengths, head circumferences, skinfold thicknesses, and arm and thigh circumferences were measured and adjusted for age using Centers for Disease Control and National Health and Nutrition Examination Survey standards. Uninfected children exposed to HIV were compared with an unexposed nearest-neighbor matched comparison group. Uninfected children exposed to HIV were compared by age to Centers for Disease Control standards for growth measures and National Health and Nutrition Examination Survey standards for body composition.

Results: One hundred eleven uninfected children exposed to HIV and 82 children not exposed to HIV were evaluated. For the matched comparison for both groups, the mean age was 10 months, 59% were male, and 73% were African American. No statistical differences were found in anthropometric measurements between uninfected children who were or were not exposed to HIV. Uninfected children exposed to HIV were smaller than US standards at birth with mean (SD) weight-for-age and weight-for-length z-scores of -0.39 (1.06); P = .002 and -0.35 (1.04); P = .005, respectively. Over the first 2 years of life, there was a trend toward increasing weight-for-age z-score, length-for-age z-score, and weight-for-length z-score in uninfected children exposed to HIV. Subscapular and triceps skinfolds among uninfected children exposed to HIV were lower than national standards and there was a trend that mid-upper arm circumference decreased over time.

Conclusions: Growth and body composition of uninfected children who were or were not exposed to HIV were similar. Uninfected children exposed to HIV weigh less at birth and show a pattern of slightly accelerated growth in the first 2 years of life. Uninfected children exposed to HIV had less subcutaneous fat and decreasing mid-upper arm circumference over time when compared with US standards.
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http://dx.doi.org/10.1016/j.jpeds.2012.12.034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3641163PMC
July 2013

Has highly active antiretroviral therapy increased the time to seroreversion in HIV exposed but uninfected children?

Clin Infect Dis 2012 Nov 31;55(9):1255-61. Epub 2012 Jul 31.

Divisions of Infectious Disease and Immunology, Miller School of Medicine, University of Miami, Florida, USA.

Background: Since the introduction of highly active antiretroviral therapy (HAART) for prevention of mother-to-child transmission of human immunodeficiency virus (HIV) in pregnancy in the United States, the time of seroreversion in infants born to HIV-infected mothers has not been documented. The objective of this study was to determine the timing of clearance of HIV antibodies and to identify any associated biological and clinical factors.

Methods: A retrospective analysis of infants who remained uninfected after perinatal HIV exposure was performed. Infant and maternal medical records from January 2000 to December 2007 were reviewed and the time of seroreversion was estimated using methods for censored survival data.

Results: In total, 744 infants were included in the study, with prenatal data available for 551 mothers. The median age of seroreversion was 13.9 months, and 14% of infants remained seropositive after 18 months, 4.3% after 21 months, and 1.2% after 24 months. Earlier age of seroreversion was associated with higher immunoglobulin G (IgG) levels at 3-7 months of age (P = .0029) and a higher rate of IgG change over the next 6 months of life (P = .003). Infants born by vaginal delivery were more likely to serorevert at a younger age (P = .0052), and maternal exposure to protease inhibitors was associated with a later age of seroreversion (P = .026).

Conclusions: Clearance of HIV antibodies in uninfected infants was found to occur at a later age than has been previously reported. Fourteen percent of the infants had persistence of HIV antibodies at or beyond 18 months of age.
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http://dx.doi.org/10.1093/cid/cis662DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4990822PMC
November 2012

Expected and actual case ascertainment and treatment rates for children infected with hepatitis C in Florida and the United States: epidemiologic evidence from statewide and nationwide surveys.

J Pediatr 2012 Nov 3;161(5):915-21. Epub 2012 Jul 3.

Department of Pediatrics, Batchelor Children's Research Institute, University of Miami Miller School of Medicine, Miami, FL, USA.

Objective: To evaluate the rate of pediatric hepatitis C virus (HCV) case ascertainment relative to the estimated number of actual cases.

Study Design: Data from Florida and United States health departments were used to assess pediatric HCV case ascertainment rates in Florida and nationwide. The percentage of children infected with HCV from Miami-Dade County receiving medical care by a pediatric gastroenterologist was estimated based on data obtained from physician questionnaires.

Results: From 2000 through 2009, 2007 children were identified as having positive HCV antibody tests in Florida, only 12% of the expected number (n = 12 155). An estimated 1.6% of the expected children with HCV who tested Ab-positive (37 of 1935) were actively followed by a pediatric gastroenterologist in Miami-Dade County, Florida. Across the United States, only 4.9% of the expected cases have been identified.

Conclusions: The identification of children infected with HCV in the nation as a whole is grossly inadequate. Only a small fraction of cases are identified. In Florida, less than 2% of children identified receive treatment. Lack of identification and lack of treatment of children infected with HCV constitute critical public health problems. Strategies to increase awareness of HCV infection and to screen at-risk individuals could substantially improve morbidity and mortality while reducing health care costs.
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http://dx.doi.org/10.1016/j.jpeds.2012.05.002DOI Listing
November 2012

Physical fitness in children infected with the human immunodeficiency virus: associations with highly active antiretroviral therapy.

AIDS Res Hum Retroviruses 2013 Jan 31;29(1):112-20. Epub 2012 Jul 31.

Divisions of Pediatric Clinical Research, University of Miami, Miami, FL 33101, USA.

Obesity, sedentary lifestyles, and antiretroviral therapies may predispose HIV-infected children to poor physical fitness. Estimated peak oxygen consumption (VO(2) peak), maximal strength and endurance, and flexibility were measured in HIV-infected and uninfected children. Among HIV-infected children, anthropometric and HIV disease-specific factors were evaluated to determine their association with VO(2) peak. Forty-five HIV-infected children (mean age 16.1 years) and 36 uninfected children (mean age 13.5 years) participated in the study. In HIV-infected subjects, median viral load was 980 copies/ml (IQR 200-11,000 copies/ml), CD4% was 28% (IQR 15-35%), and 82% were on highly active antiretroviral therapy (HAART). Compared to uninfected children, after adjusting for age, sex, race, body fat, and siblingship, HIV-infected children had lower VO(2) peak (25.92 vs. 30.90 ml/kg/min, p<0.0001), flexibility (23.71% vs. 46.09%, p=0.0003), and lower-extremity strength-to-weight ratio (0.79 vs. 1.10 kg lifted/kg of body weight, p=0.002). Among the HIV-infected children, a multivariable analysis adjusting for age, sex, race, percent body fat, and viral load showed VO(2) peak was 0.30 ml/kg/min lower per unit increase in percent body fat (p<0.0001) and VO(2) peak (SE) decreased 29.45 (± 1 .62), 28.70 (± 1.87), and 24.09 (± 0.75) ml/kg/min across HAART exposure categories of no exposure, <60, and ≥ 60 months, respectively (p<0.0001). HIV-infected children had, in general, lower measures of fitness compared to uninfected children. Factors negatively associated with VO(2) peak in HIV-infected children include higher body fat and duration of HAART ≥ 60 months. Future studies that elucidate the understanding of these differences and mechanisms of decreased physical fitness should be pursued.
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http://dx.doi.org/10.1089/AID.2012.0047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3537323PMC
January 2013

Serial measurements of serum NT-proBNP as markers of left ventricular systolic function and remodeling in children with heart failure.

Am Heart J 2010 Oct;160(4):776-83

Divisions of Pediatric Cardiology, Miami, FL, USA.

Background: Increasing serum levels of N-terminal pro-hormone brain natriuretic peptide (NT-proBNP) are associated with worsening heart failure (HF) in adults. We determined whether changes in NT-proBNP level are associated with changes in symptoms and left ventricular (LV) systolic function and remodeling in children with HF secondary to dilated cardiomyopathy.

Methods: We retrospectively examined associations between serum NT-proBNP levels and NYHA/Ross functional class, LV systolic and diastolic diameter (LVSD-z and LVDD-z), LV ejection fraction (LVEF), and LV shortening fraction (LVSF-z) using generalized linear mixed models. Fluctuation in functional class of subjects was also modeled using logistic regression and receiver operating characteristic (ROC) curves.

Results: In 36 children (14 males), a 10-fold increase in NT-proBNP serum levels was associated (P < .001) with a 9.8% decrease in LVEF, a 3.25-unit drop in LVSF-z, a 1.53-unit increase in LVDD-z, a 2.64-unit increase in LVSD-z, and an increased odds of being in functional class III/IV (OR 85.5; 95% CI, 10.9 to 671.0). An NT-proBNP level greater than 1000 pg/mL identified children constantly or intermittently in functional class III-IV with 95% sensitivity and 80% specificity. The reliability of a single NT-proBNP value was 0.61, but the means for two and three NT-proBNP values were 0.76 and 0.82, respectively.

Conclusions: In children with HF, NT-proBNP is associated with cardiac symptoms and indices of LV systolic dysfunction and remodeling. NT-proBNP >1000 pg/mL identifies highly symptomatic children. Within subject serial measurements of NT-proBNP are needed for a reliable and accurate determination of disease status and/or course.
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http://dx.doi.org/10.1016/j.ahj.2010.07.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2964279PMC
October 2010

Is heart period variability associated with the administration of lifesaving interventions in individual prehospital trauma patients with normal standard vital signs?

Crit Care Med 2010 Aug;38(8):1666-73

Department of Health and Kinesiology, The University of Texas at San Antonio, TX, USA.

Objective: To determine whether heart period variability provides added value in identifying the need for lifesaving interventions (LSI) in individual trauma patients with normal standard vital signs upon early medical assessment.

Design: Retrospective database review.

Setting: Helicopter transport to Level 1 trauma center and first 24 hrs of in-hospital care.

Patients: Prehospital trauma patients requiring helicopter transport to Level 1 trauma center.

Measurements And Main Results: Heart period variability was analyzed from electrocardiographic recordings collected from 159 prehospital trauma patients with normal standard vital signs (32 LSI patients, 127 No-LSI patients). Although 13 of the electrocardiogram derived metrics demonstrated simple (i.e., univariate) discrimination between groups, at the multivariate level, only fractal dimension by curve length (FD-L) was uniquely associated with group membership (LSI vs. No-LSI, p = .0004). Whereas the area under the receiver operating characteristics curve for FD-L was 0.70, the overall correct classification rate (true positives and true negatives) of 82% was only 2% higher than the baseline prediction rate of 80% (i.e., no information except for the known proportion of overall No-LSI cases, 127 of 159 patients). Furthermore, 84% of the individual FD-L values for the LSI group were within the range of the No-LSI group.

Conclusions: Only FD-L was uniquely able to distinguish patient groups based on mean values when standard vital signs were normal. However, the accuracy of FD-L in distinguishing between patients was only slightly better than the baseline prediction rate. There was also very high overlap of individual heart period variability values between groups, so many LSI patients could be incorrectly classified as not requiring an LSI if a single heart period variability value was used as a triage tool. Based on this analysis, heart period variability seems to have limited value for prediction of LSIs in prehospital trauma patients with normal standard vital signs.
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http://dx.doi.org/10.1097/CCM.0b013e3181e74cabDOI Listing
August 2010

Influence of body mass index on outcome of pediatric chronic hepatitis C virus infection.

J Pediatr Gastroenterol Nutr 2010 Aug;51(2):191-7

Division of Clinical Research, Department of Pediatrics, Batchelor Children's Research Institute, University of Miami, Miami, FL, USA.

Background And Aims: Evidence demonstrates that obesity is associated with progression of chronic hepatitis C virus (HCV) infection and poor response to interferon therapy among HCV-infected adults. However, this evidence has been confounded by multiple comorbidities present in adult cohorts and the use of single adult doses.

Patients And Methods: We performed a retrospective investigation to evaluate the role of body mass index (BMI) in chronic HCV progression and response to therapy in the children. One hundred twenty-three children and teenagers studied at Children's Hospital Boston for HCV infection between 1998 and 2007 were included. Patients' weight and height at the time of liver biopsy or before and after HCV therapy were obtained and BMI was calculated.

Results: The presence of steatosis was statistically associated with higher mean (+/-SE) BMI percentiles (72nd +/- 5.8 vs 58th +/- 3.5) percentile; F(1,101) = 4.2, P = 0.04. Nonresponders to treatment had a higher mean (+/-SE) BMI percentile (70th +/- 7.4) when compared with responders (50th +/- 6.5) in univariate and multivariate analyses (P = 0.04, P = 0.02, respectively). Using a multivariate model, it was calculated that 1 standard deviation (1 z-score unit) increase in baseline BMI z score is associated with a 12% decrease in the probability of sustained virologic response.

Conclusions: Overweight adversely affects the progression of chronic HCV liver disease and is associated with diminished response to antiviral therapy using weight-based dosing in a cohort with minimal comorbidities.
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http://dx.doi.org/10.1097/MPG.0b013e3181d32756DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2910782PMC
August 2010

Oxygen transport characterization of a human model of progressive hemorrhage.

Resuscitation 2010 Aug 24;81(8):987-93. Epub 2010 Apr 24.

Virginia Commonwealth University Reanimation Engineering Shock Center (VCURES), 1201 East Marshall Street, P.O. Box 980401, Richmond, VA 23298, United States.

Background: Hemorrhage continues to be a leading cause of death from trauma sustained both in combat and in the civilian setting. New models of hemorrhage may add value in both improving our understanding of the physiologic responses to severe bleeding and as platforms to develop and test new monitoring and therapeutic techniques. We examined changes in oxygen transport produced by central volume redistribution in humans using lower body negative pressure (LBNP) as a potential mimetic of hemorrhage.

Methods And Results: In 20 healthy volunteers, systemic oxygen delivery and oxygen consumption, skeletal muscle oxygenation and oral mucosa perfusion were measured over increasing levels of LBNP to the point of hemodynamic decompensation. With sequential reductions in central blood volume, progressive reductions in oxygen delivery and tissue oxygenation and perfusion parameters were noted, while no changes were observed in systemic oxygen uptake or markers of anaerobic metabolism in the blood (e.g., lactate, base excess). While blood pressure decreased and heart rate increased during LBNP, these changes occurred later than the reductions in tissue oxygenation and perfusion.

Conclusions: These findings indicate that LBNP induces changes in oxygen transport consistent with the compensatory phase of hemorrhage, but that a frank state of shock (delivery-dependent oxygen consumption) does not occur. LBNP may therefore serve as a model to better understand a variety of compensatory physiological changes that occur during the pre-shock phase of hemorrhage in conscious humans. As such, LBNP may be a useful platform from which to develop and test new monitoring capabilities for identifying the need for intervention during the early phases of hemorrhage to prevent a patient's progression to overt shock.
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http://dx.doi.org/10.1016/j.resuscitation.2010.03.027DOI Listing
August 2010

An improved estimator for the hydration of fat-free mass from in vivo measurements subject to additive technical errors.

Physiol Meas 2010 Apr 24;31(4):497-512. Epub 2010 Feb 24.

Department of Pediatrics, University of Miami Miller School of Medicine, FL 33101, USA.

The hydration of fat-free mass, or hydration fraction (HF), is often defined as a constant body composition parameter in a two-compartment model and then estimated from in vivo measurements. We showed that the widely used estimator for the HF parameter in this model, the mean of the ratios of measured total body water (TBW) to fat-free mass (FFM) in individual subjects, can be inaccurate in the presence of additive technical errors. We then proposed a new instrumental variables estimator that accurately estimates the HF parameter in the presence of such errors. In Monte Carlo simulations, the mean of the ratios of TBW to FFM was an inaccurate estimator of the HF parameter, and inferences based on it had actual type I error rates more than 13 times the nominal 0.05 level under certain conditions. The instrumental variables estimator was accurate and maintained an actual type I error rate close to the nominal level in all simulations. When estimating and performing inference on the HF parameter, the proposed instrumental variables estimator should yield accurate estimates and correct inferences in the presence of additive technical errors, but the mean of the ratios of TBW to FFM in individual subjects may not.
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http://dx.doi.org/10.1088/0967-3334/31/4/003DOI Listing
April 2010

Body mass index as a function of length of United States residency among Haitian immigrant children.

Ethn Dis 2010 ;20(1):22-8

Department of Epidemiology and Public Health, University of Miami, Leonard M. Miller School of Medicine, Miami, Florida 33130, USA.

Objectives: 1) To compare Body Mass Index (BMI) percentiles of Haitian-born children and US-born Haitian Children; 2) To assess the relationship between time in the United States and BMI percentiles for Haitian-born children; and 3) To compare BMI percentiles of Haitian-born and US-born Haitian children to other US pediatric populations included in the 2003-2004 National Health and Nutrition Examination Survey (NHANES) data.

Design: Retrospective medical chart review of demographic and anthropometric characteristics.

Setting: Center for Haitian Studies, a nonprofit community based organization that provides health care and social services to the Haitian community.

Patients: The medical charts from 250 children ages 2-18 who received medical care at CHS between January 1, 2004 and July 30, 2006.

Main Outcome Measures: 1) Overweight (> or = 85th to <95th BMI percentile) and 2) Obese (> or = 95th BMI percentile).

Results: Thirty percent of Haitian-born and 51% of US-born Haitian children were > or = 85th percentile for BMI. US-born children had higher BMI percentiles than Haitian-born children (81st percentile vs 68th percentile). Among Haitian-born children, BMI percentile increased by 3.7% for each year of US residency. When compared to NHANES data, Haitian-born children were less likely to be overweight than non-Hispanic Blacks, Mexican Americans, and non-Hispanic White children, or for all groups combined (14.9% vs 33.6%, 95% CI 9.8%-22.2%), but were as likely to be obese (14.9% vs 17.7%, 95% CI, 9.8%-22.2%).

Conclusions: Haitian-born children are currently experiencing a 3.7% BMI percentile increase for each year of US residency and are as likely to be overweight as other US minority children making them potentially at increased risk for health consequences associated with obesity.
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April 2010

Reduction of insulin resistance with effective clearance of hepatitis C infection: results from the HALT-C trial.

Clin Gastroenterol Hepatol 2010 May 12;8(5):458-62. Epub 2010 Feb 12.

Department of Pediatrics, Batchelor Children's Research Institute, University of Miami, Miami, Florida, USA.

Background & Aims: Hepatitis C virus (HCV) infection is associated with an increased prevalence of diabetes and insulin resistance (IR); whether this is a causal relationship has not been established.

Methods: We performed a longitudinal study within the lead-in phase of the Hepatitis C Antiviral Long-Term Treatment against Cirrhosis (HALT-C) Trial to evaluate whether suppression of hepatitis C is associated with improvement in IR. Participants had advanced hepatic fibrosis and carried non-3 HCV genotypes (n = 96). Patients underwent 24 weeks of pegylated interferon and ribavirin therapy and were categorized into HCV clearance groups at week 20 on the basis of HCV RNA levels; null responders had <1 log(10) decline (n = 38), partial responders had >or=1 log(10) decline (n = 37) but detectable HCV RNA, and complete responders had no detectable HCV RNA (n = 21). The primary outcome was change (week 20 minus week 0) in IR by using the homeostasis model assessment (HOMA2-IR).

Results: Adjusting only for baseline HOMA2-IR, mean HOMA2-IR differences were -2.23 (complete responders), -0.90 (partial responders), and +0.18 (null responders) (P = .036). The observed differences in mean HOMA2-IR scores were ordered in a linear fashion across response groups (P = .01). The association between HCV clearance and improvement in HOMA2-IR could not be accounted for by adiponectin or tumor necrosis factor-alpha and was independent of potential confounders including age, gender, ethnicity, body mass index, duration of infection, medications used, and fibrosis.

Conclusions: HCV suppression correlates with improvement in IR. These data provide further support for a role of HCV in the development of insulin resistance.
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http://dx.doi.org/10.1016/j.cgh.2010.01.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2856733PMC
May 2010

Tracking central hypovolemia with ecg in humans: cautions for the use of heart period variability in patient monitoring.

Shock 2010 Jun;33(6):583-9

US Army Institute of Surgical Research, Fort Sam Houston, Texas, USA.

Heart period variability (HPV) metrics have been suggested for use in medical monitoring of trauma patients. This study sought to ascertain the use of various HPV metrics in tracking central blood volume during simulated hemorrhage in individual humans. One hundred one healthy nonsmoking volunteers (58 men, 43 women) were instrumented for continuous measurement of electrocardiogram and beat-by-beat finger arterial blood pressure. Stroke volume (SV) was estimated from the arterial pulse wave and used to reflect central blood volume. Progressive lower body negative pressure (LBNP) was applied in 5-min stages until the onset of impending hemodynamic decompensation (systolic blood pressure <70 mmHg and/or presyncopal symptoms). HPV was assessed with analysis of R-to-R intervals using both linear (time and frequency domains) and nonlinear (e.g., complexity, fractality) methods. Application of increasing LBNP caused progressive reductions of SV, whereas arterial pressures changed only minimally and late. Group LBNP stage means for each HPV metric changed progressively and were strongly correlated with the mean decrease in SV (|r| > or = 0.87). To ascertain the utility of the HPV metrics to track individual responses to central hypovolemia, the difference scores for each HPV metric were correlated at each successive LBNP level, with percentage change in SV at the subject level. This cross-correlation of difference scores revealed that none of the HPV metrics showed strong and consistent correlations (|r| < or = 0.49) with percentage change in SV across successive LBNP levels. Although aggregate group mean values for HPV metrics are well correlated with SV changes during central hypovolemia, these metrics are less reliable when tracking individual reductions in central volume during LBNP. HPV metrics, therefore, may not be useful in monitoring hemorrhagic injuries in individual patients.
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http://dx.doi.org/10.1097/SHK.0b013e3181cd8cbeDOI Listing
June 2010

Views of hypertension among young African Americans who vary in their risk of developing hypertension.

Ethn Dis 2009 ;19(1):28-34

Department of Nutrition, University of North Carolina at Greensboro, 309 Stone Bldg, Greensboro, NC 27402, USA.

Objectives: To describe beliefs about hypertension and health education of young African American adults varying in their hypertension risk status.

Design: Fifty-eight African American young adults (17-20 years) were selected based on low and high risk criteria for hypertension assessed in earlier investigations of hemodynamic responses to stress. The sample included 15 high risk males, 13 low risk males, 14 high risk females, and 16 low risk females who were interviewed indepth about their hypertension beliefs and health education experiences. Variable-based matrices identified participants with similar responses.

Results: Overall, participants had a limited understanding of hypertension. For example, they linked the condition to eating a diet high in pork and fat and having a positive family history of hypertension with little acknowledgement of weight, smoking, race and sex as key contributors to hypertension onset. Distinctions were found between risk categories and along sex lines. Most high risk participants believed stress could cause hypertension. High risk females believed that they were at risk for developing hypertension but lacked prevention strategies. High risk males were generally uninformed about risk or prevention. More low risk females believed in prevention compared to few low risk males. Participants reported little formal health education about hypertension and recommended that hypertension education be improved through more effective and relevant approaches in high school health education classes.

Conclusions: These findings support the need for comprehensive and revitalized hypertension prevention programs for young African Americans. Participant views varied with hypertension risk status and gender suggesting that targeted educational efforts should reflect these differences.
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April 2009

The association of race and sex to the pressure natriuresis response to stress.

Ethn Dis 2007 ;17(3):498-502

Georgia Prevention Institute, Medical College of Georgia, MCG Annex H.S. 1640, Augusta, GA 30912-4534, USA.

Objective: Sympathetic nervous system activation promoting sodium retention has long been recognized to play a significant role in the development and maintenance of salt-sensitive hypertension. The purpose of this study was to examine the influence of race and sex on the pressure natriuresis response to prolonged behavioral stress in youth.

Methods: The 190 subjects included 94 boys (41 African American, 53 Caucasian) and 96 girls (44 African American, 52 Caucasian) of similar age (17-19 years). The stress test was composed of a one hour competitive video game task preceded and followed by two-hour rest periods. Blood pressure (BP) was obtained at 15 minute intervals and sodium excretion (U(Na)V) was measured hourly. The general linear model was used to model the effects of race, sex, and their interaction on the variables of interest.

Results: Caucasians, compared to African Americans, had a greater change in U(Na)V (F[1,183] = 5.28, P = .0227), as did boys compared to girls (F[1,183] = 5.72, P = .0178), with no interaction between race and sex. The race-by-sex interaction was significant for the change in systolic BP (F[1,183] = 5.66, P = .0184), with Caucasian girls showing a smaller change than the other three race/sex groups.

Conclusion: African Americans have a reduced natriuretic response to stress, which may be a marker or mechanism for the development of salt-sensitive hypertension in this population. The race difference within girls is of interest and requires further investigation.
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January 2008

Correlates of adherence to a physical activity program in young African-American girls.

Obesity (Silver Spring) 2007 Mar;15(3):695-703

Medical College of Georgia, Department of Psychiatry and Health Behavior, 1120 Fifteenth Street, Augusta, GA 30912-3800, USA.

Objective: The goal was to identify correlates of adherence to a structured physical activity (PA) program.

Research Methods And Procedures: Subjects were 136 8- to 12-year-old African-American girls. Potential correlates at baseline were: 1) fitness index (FI: % body fat from DXA and cardiovascular fitness from treadmill test), and 2) self-esteem, anxiety, attitude to school and teachers, relationship with parents, and interpersonal relations (Behavioral Assessment System for Children). The 10-month PA program included 80 minutes of PA offered 5 days/wk. Regression tree classification was used to model attendance.

Results: Six splits occurred (34% total variance explained). Less anxious subjects attended more often than highly anxious subjects (3 days/wk vs. 1.5 days/wk) did. Subjects with a healthier FI attended more often than those with a less healthy FI (3 days/wk vs. 0.5 days/wk) did. Younger subjects attended more often than older ones (3 days/wk vs. 2.5 days/wk) did. The next two splits were again with anxiety (3.5 days/wk vs. 3 days/wk) and FI (3 days/wk vs. 2.5 days/wk). Finally, subjects with higher levels of self-esteem attended more often than those with lower levels (3.5 days/wk vs. 2 days/wk) did.

Discussion: Subjects who were self-confident, younger, fitter, and less anxious were more likely to participate regularly. This suggests that children who may be more likely to benefit from a PA program are less likely to participate. To enhance participation in PA programs, especially in older African-American girls: 1) psychological concerns should be identified and addressed before enrollment, and 2) programs should be designed to be appealing to children of all fitness levels.
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http://dx.doi.org/10.1038/oby.2007.552DOI Listing
March 2007

A 4-day sodium-controlled diet reduces variability of overnight sodium excretion in free-living normotensive adolescents.

J Am Diet Assoc 2007 Mar;107(3):490-4

Department of Nutrition, University of North Carolina at Greensboro, Greensboro, NC 27402, USA.

The present analysis examined changes in the variability of overnight sodium excretion in 84 free-living adolescents (ages 15 to 19 years) on a 4-day sodium-controlled diet in which foods provided were selected by adolescents from an extensive list of menu items. The only selection criterion imposed was that foods selected for each day contain 4,000+/-200 mg sodium. Adolescents collected overnight urine samples. Repeated measures analysis of variance tested the effect of diet day on overnight sodium excretion, overnight urinary sodium concentration, and overnight urinary volume. Variance ratio test evaluated changes in overnight sodium excretion variance across days. Day 4 overnight sodium excretion was statistically lower than days 1 to 3 (1.84 vs 6.54, 5.94, and 5.52 mEq/h [1.84 vs 6.54, 5.94, and 5.52 mmol/h]). Day 4 overnight urinary sodium concentration was lower than days 1 to 3 (32.16 vs 119.64, 109.61, and 111.32 mEq/L [32.16 vs 119.64, 109.61, and 111.32 mmol/L]). The variance of overnight sodium excretion from day 1 to day 4 was reduced 10-fold from 20.1 mEq/h (20.1 mmol/h) to 1.90 mEq/h (1.90 mmol/h). Daily overnight urine volumes remained constant, averaging 451.7 mL/day. The dietary protocol successfully reduced the variability of sodium intake as estimated by overnight sodium excretion in free-living adolescents. The protocol could be expanded to include baseline values, additional days of sodium control, and varying levels of dietary sodium intake.
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http://dx.doi.org/10.1016/j.jada.2006.12.005DOI Listing
March 2007

R-wave amplitude in lead II of an electrocardiograph correlates with central hypovolemia in human beings.

Acad Emerg Med 2006 Oct 13;13(10):1003-10. Epub 2006 Sep 13.

U.S. Army Institute of Surgical Research, 3400 Rawley E. Chambers Avenue, Fort Sam Houston, TX 78234-6513.

Objectives: Previous animal and human experiments have suggested that reduction in central blood volume either increases or decreases the amplitude of R waves in various electrocardiograph (ECG) leads depending on underlying pathophysiology. In this investigation, we used graded central hypovolemia in adult volunteer subjects to test the hypothesis that moderate reductions in central blood volume increases R-wave amplitude in lead II of an ECG.

Methods: A four-lead ECG tracing, heart rate (HR), estimated stroke volume (SV), systolic blood pressure, diastolic blood pressure, and mean arterial pressure were measured during baseline supine rest and during progressive reductions of central blood volume to an estimated volume loss of >1,000 mL with application of lower-body negative pressure (LBNP) in 13 healthy human volunteer subjects.

Results: Lower-body negative pressure resulted in a significant progressive reduction in central blood volume, as indicated by a maximal decrease of 65% in SV and maximal elevation of 56% in HR from baseline to -60 mm Hg LBNP. R-wave amplitude increased (p < 0.0001) linearly with progressive LBNP. The amalgamated correlation (R2) between average stroke volume and average R-wave amplitude at each LBNP stage was -0.989.

Conclusions: These results support our hypothesis that reduction of central blood volume in human beings is associated with increased R-wave amplitude in lead II of an ECG.
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http://dx.doi.org/10.1197/j.aem.2006.07.010DOI Listing
October 2006

Heart rate variability and its association with mortality in prehospital trauma patients.

J Trauma 2006 Feb;60(2):363-70; discussion 370

Department of Health and Kinesiology, The University of Texas at San Antonio, San Antonio, Texas 78249, USA.

Background: Accurate prehospital triage of trauma patients is difficult, especially in mass casualty situations. Accordingly, the U.S. Military has initiated a program directed toward improving noninvasive prehospital triage algorithms based on available physiologic data. The purpose of this study was to assess heart rate variability and its association with mortality in prehospital trauma patients.

Methods: Trauma patients without significant head injury requiring helicopter transport were identified from a retrospective research database. An equal number, unmatched sample of patients who lived were compared with those who died (n = 15 per group). All patients were transported to a single Level I urban trauma center. The primary independent variable was mortality. Patients with Abbreviated Injury Scale head scores >2 were excluded from the analysis, so that the effects seen were based on hemorrhagic shock. Age, sex, Glasgow Coma Scale score (GCS), blood pressure, pulse pressure, pulse, intubation rate, SpO2, mechanism of injury, transport time, and time of death after admission were recorded. R-waves from the first available 120 seconds of usable data were detected from normal electrocardiograms and heart rate variability was assessed.

Results: Patients who died demonstrated a lower GCS (7.9 +/- 1.4 versus 14.4 +/- 0.2; p = 0.0001) and higher intubation rate (53% of patients who died versus 0% patients who lived). Pulse rate, arterial pressure, and SpO2 were not distinguishable statistically between groups (p = 0.08), but pulse pressure was lower in patients who died (39 +/- 3 versus 50 +/- 2 mm Hg; p = 0.01). Compared with patients who lived, those who died had lower normalized low-frequency (LF) power (42 +/- 6 versus 62 +/- 4 LFnu; p = 0.009), higher high-frequency (HF) power (42 +/- 3 versus 32 +/- 3 HFnu; p = 0.04) and higher HF-to-LF ratio (144 +/- 30 versus 62 +/- 11nu; p = 0.01). With absolute HF/LF adjusted for GCS, the intergroup variance accounted for by HF/LF was reduced to 6% (p = 0.16).

Conclusions: Analysis of heart rate variability provides insight into adequacy of autonomic compensation to severe trauma. In our cohort of trauma patients, low pulse pressures coupled with relatively higher parasympathetic than sympathetic modulation characterized and separated patients who died versus patients who survived traumatic injuries when standard physiologic measurements are not different. These data do not suggest advantages of heart rate variability analysis over GCS scores, but suggest future possibilities for remote noninvasive triage of casualties when GCS scores are unattainable.
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http://dx.doi.org/10.1097/01.ta.0000196623.48952.0eDOI Listing
February 2006

Use and misuse of p-values in designed and observational studies: guide for researchers and reviewers.

Authors:
David A Ludwig

Aviat Space Environ Med 2005 Jul;76(7):675-80

Dept. of Pediatrics, Medical College of Georgia, Georgia Prevention Institute, Augusta, GA 30912-3710, USA.

Analysis of scientific data involves many components, one of which is often statistical testing with the calculation of p-values. However, researchers too often pepper their papers with p-values in the absence of critical thinking about their results. In fact, statistical tests in their various forms address just one question: does an observed difference exceed that which might reasonably be expected solely as a result of sampling error and/or random allocation of experimental material? Such tests are best applied to the results of designed studies with reasonable control of experimental error and sampling error, as well as acquisition of a sufficient sample size. Nevertheless, attributing an observed difference to a specific treatment effect requires critical thinking on the part of the scientist. Observational studies involve data sets whose size is usually a matter of convenience with results that reflect a number of potentially confounding factors. In this situation, statistical testing is not appropriate and p-values may be misleading; other more modern statistical tools should be used instead, including graphic analysis, computer-intensive methods, regression trees, and other procedures broadly classified as bioinformatics, data mining, and exploratory data analysis. In this review, the utility of p-values calculated from designed experiments and observational studies are discussed, leading to the formation of a decision tree to aid researchers and reviewers in understanding both the benefits and limitations of statistical testing.
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July 2005

School-based smoking prevention research.

Authors:
David A Ludwig

J Adolesc Health 2005 Jul;37(1):5-6; author reply 6-8

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http://dx.doi.org/10.1016/j.jadohealth.2005.04.007DOI Listing
July 2005

African-American adolescents' stress responses after the 9/11/01 terrorist attacks.

J Adolesc Health 2005 Mar;36(3):201-7

Department of Pediatrics, Georgia Institute for Prevention of Human Diseases and Accidents, Medical College of Georgia, Augusta, GA, USA.

Purpose: To examine the impact of indirect exposure to the 9/11/01 attacks upon physical and emotional stress-related responses in a community sample of African-American (AA) adolescents.

Methods: Three months after the 9/11/01 terrorist attacks, 406 AA adolescents (mean age [SD] of 16.1 +/- 1.3 years) from an inner-city high school in Augusta, GA were evaluated with a 12-item 5-point Likert scale measuring loss of psychosocial resources (PRS) such as control, hope, optimism, and perceived support, a 17-item 5-point Likert scale measuring post-traumatic stress symptomatology (PCL), and measures of state and trait anger, anger expression, and hostility. Given the observational nature of the study, statistical differences and correlations were evaluated for effect size before statistical testing (5% minimum variance explained). Bootstrapping was used for testing mean differences and differences between correlations.

Results: PCL scores indicated that approximately 10% of the sample was experiencing probable clinically significant levels of post-traumatic distress (PCL score > 50). The PCL and PRS were moderately correlated with a r = .59. Gender differences for the PCL and PRS were small, accounting for 1% of the total variance. Higher PCL scores were associated with higher state anger (r = .47), as well as measures of anger-out (r = .32) and trait anger (r = .34). Higher PRS scores were associated only with higher state anger (r = .27). Scores on the two 9/11/01-related scales were not statistically associated (i.e., less than 5% of the variance explained) with traits of anger control, anger-in, or hostility.

Conclusions: The majority of students were not overly stressed by indirect exposure to the events of 9/11/01, perhaps owing to the temporal, social, and/or geographical distance from the event. Those who reported greater negative impact appeared to also be experiencing higher levels of current anger and exhibited a characterologic style of higher overt anger expression.
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http://dx.doi.org/10.1016/j.jadohealth.2004.02.035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3286004PMC
March 2005