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    468 results match your criteria Clinical Epidemiology [Journal]

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    Effects of chronic exposure of hydroxychloroquine/chloroquine on the risk of cancer, metastasis, and death: a population-based cohort study on patients with connective tissue diseases.
    Clin Epidemiol 2017 3;9:545-554. Epub 2017 Nov 3.
    Department of Primary Care and Population Health, University College London, UK.
    Background: Hydroxychloroquine and chloroquine may reduce the risk of cancer as they inhibit autophagy, in particular, in people with connective tissue diseases.

    Methods: The hazard ratios of cancers, metastases, and death were assessed in adults with connective tissue diseases prescribed hydroxychloroquine/chloroquine for at least 1 year in comparison with unexposed individuals with the same underlying conditions. A competing risk survival regression analysis was performed. Read More

    Mortality in adults with and without diabetes: is the gap widening?
    Clin Epidemiol 2017 3;9:537-544. Epub 2017 Nov 3.
    Public Health College, Harbin Medical University, Harbin, China.
    Objective: We aimed to assess if the gap in mortality between adults with and without diabetes has widened over time in US adults.

    Methods And Study Design: This cohort study included 44,041 adults with diabetes from the US National Health Interview Survey between 1986 and 2009 linked to the National Mortality Index data up to 2011. Each participant with diabetes was matched to two participants without diabetes by age, sex, race, survey year, and region of residence (88,082 persons without diabetes). Read More

    Familial aggregation of myasthenia gravis in affected families: a population-based study.
    Clin Epidemiol 2017 2;9:527-535. Epub 2017 Nov 2.
    Department of Anesthesiology, Chang Gung Memorial Hospital.
    Introduction: Myasthenia gravis (MG) is clinically heterogeneous and can be life-threatening if bulbar or respiratory muscles are involved. However, relative contributions of genetic, shared, and nonshared environmental factors to MG susceptibility remain unclear. The aim of this study was to examine the familial aggregation and heritability of MG and the relative risks (RRs) of other autoimmune diseases in the relatives of patients with MG. Read More

    Liver-related morbidity and mortality in patients with chronic hepatitis C and cirrhosis with and without sustained virologic response.
    Clin Epidemiol 2017 24;9:501-516. Epub 2017 Oct 24.
    Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre.
    Background: Chronic hepatitis C (CHC) causes liver cirrhosis in 5%-20% of patients, leading to increased morbidity and mortality. This study aimed to estimate liver-related morbidity and mortality among patients with CHC and cirrhosis in Denmark with and without antiviral treatment and sustained virologic response (SVR). Furthermore we aimed to estimate the rate of hepatocellular carcinoma (HCC) and decompensation associated with certain prognostic factors. Read More

    Healthy lifestyle behavior and risk of long duration troublesome neck pain or low back pain among men and women: results from the Stockholm Public Health Cohort.
    Clin Epidemiol 2017 11;9:491-500. Epub 2017 Oct 11.
    Unit of Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
    Background: The role of healthy lifestyle behavior (HLB) in terms of physical activity, alcohol intake, smoking, and diet put together has not yet been explored for the risk of low back pain (LBP) and neck pain (NP). Our aim was to study if an HLB is protective against the onset of long duration troublesome LBP and NP in men and women.

    Methods: Two cohorts from the Stockholm Public Health Cohort, free from LBP (n=12,483) and NP (n=10,539), respectively, in 2006, were surveyed with questionnaires. Read More

    Accuracy of the hypospadias diagnoses and surgical treatment registrations in the Danish National Patient Register.
    Clin Epidemiol 2017 3;9:483-489. Epub 2017 Oct 3.
    Department of Public Health, Section for Epidemiology, Aarhus University, Aarhus, Denmark.
    Purpose: The Danish National Health registers provide a valuable data source that offers unique opportunities for observational research, including studies on the congenital anomaly hypospadias. The accuracy of the diagnosis and surgical treatment registration of hypospadias in the Danish National Patient Register (DNPR) remains unknown.

    Patients And Methods: We randomly sampled 500 patients diagnosed with hypospadias in the DNPR from January 1, 1995 to December 31, 2012. Read More

    Validation of autism spectrum disorder diagnoses recorded in the Clinical Practice Research Datalink, 1990-2014.
    Clin Epidemiol 2017 15;9:475-482. Epub 2017 Sep 15.
    Boston Collaborative Drug Surveillance Program, Boston University School of Public Health, Lexington, MA, USA.
    Background: Prior studies have reported that the validity of autism spectrum disorder (ASD) diagnoses recorded in the Clinical Practice Research Datalink (CPRD) was high; however, diagnostic criteria and screening practices have changed since the last study was published in 2004.

    Objectives: 1) To calculate the positive predictive value (PPV) of ASD diagnoses recorded in the CPRD compared to original medical records and 2) to describe characteristics of cases and use of clinical codes that support the ASD diagnosis as recorded in the electronic data by general practitioners over time.

    Methods: We identified children with a code for ASD (autism spectrum disorder, autism, Asperger's, or pervasive developmental disorder) in the CPRD from 1990 to 2014. Read More

    Psychiatric conditions and general practitioner attendance prior to HPV vaccination and the risk of referral to a specialized hospital setting because of suspected adverse events following HPV vaccination: a register-based, matched case-control study.
    Clin Epidemiol 2017 12;9:465-473. Epub 2017 Sep 12.
    Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus C, Denmark.
    Aim: No association between human papilloma virus (HPV) vaccination and numerous diseases has been found. Still, a large number of Danish women are reporting suspected adverse events. Other factors may play a role, and the aim of this study is to examine the association between psychiatric conditions, general practitioner (GP) attendance and indicators of psychological symptoms prior to HPV vaccination and the risk of referral to an HPV center following vaccination. Read More

    Prediction models for the mortality risk in chronic dialysis patients: a systematic review and independent external validation study.
    Clin Epidemiol 2017 5;9:451-464. Epub 2017 Sep 5.
    Department of Clinical Epidemiology, Leiden University Medical Center, Leiden.
    Objective: In medicine, many more prediction models have been developed than are implemented or used in clinical practice. These models cannot be recommended for clinical use before external validity is established. Though various models to predict mortality in dialysis patients have been published, very few have been validated and none are used in routine clinical practice. Read More

    Migraine and risk of stroke and acute coronary syndrome in two case-control studies in the Danish population.
    Clin Epidemiol 2017 31;9:439-449. Epub 2017 Aug 31.
    Research Center for Prevention and Health, Rigshospitalet - Glostrup, Copenhagen University, Glostrup, Denmark.
    Introduction: Migraine has consistently been associated with increased risk of ischemic stroke, while the evidence for a relation with other types of stroke or coronary outcomes is limited. We examined the association between migraine and stroke and acute coronary syndrome (ACS) subtypes and the influence of potential confounding factors.

    Methods: All first-time hospital contacts for stroke (n=155,216) or ACS (n=97,799) were identified in Danish National Patient Registers and matched with 2 control groups of the background population. Read More

    Somatic symptom profiles in the general population: a latent class analysis in a Danish population-based health survey.
    Clin Epidemiol 2017 23;9:421-433. Epub 2017 Aug 23.
    Department of Public Health, University of Copenhagen, Copenhagen.
    Purpose: The aim of this study was to identify and describe somatic symptom profiles in the general adult population in order to enable further epidemiological research within multiple somatic symptoms.

    Methods: Information on 19 self-reported common somatic symptoms was achieved from a population-based questionnaire survey of 36,163 randomly selected adults in the Capital Region of Denmark (55.4% women). Read More

    Positive predictive values of ICD-10 codes to identify incident acute pancreatitis and incident primary malignancy in the Scandinavian national patient registries among women with postmenopausal osteoporosis.
    Clin Epidemiol 2017 17;9:411-419. Epub 2017 Aug 17.
    Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
    Background: Validation of definitions used to identify conditions of interest is imperative to epidemiologic studies based on routinely collected data. The objective of the study was thus to estimate positive predictive values (PPVs) of International Classification of Diseases, 10th Revision (ICD-10) codes to identify cases of incident acute pancreatitis leading to hospitalization and incident primary malignancy in the Scandinavian (Denmark, Norway, and Sweden) national patient registries in women with postmenopausal osteoporosis (PMO).

    Methods: This validation study included postmenopausal (defined as 55 years or older) women with osteoporosis, identified between 2005-2014. Read More

    Misclassification of hypertrophic cardiomyopathy: validation of diagnostic codes.
    Clin Epidemiol 2017 9;9:403-410. Epub 2017 Aug 9.
    Heart Center and Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
    Purpose: To validate diagnostic codes for hypertrophic cardiomyopathy (HCM), analyze misclassfications, and estimate the prevalence of HCM in an unselected Swedish regional cohort.

    Patients And Methods: Using the hospitals' electronic medical records (used for the Swedish National Patient Register), we identified 136 patients from 2006 to 2016 with the HCM-related codes 142.1 and 142. Read More

    Irritable bowel symptoms and the development of common mental disorders and functional somatic syndromes identified in secondary care - a long-term, population-based study.
    Clin Epidemiol 2017 31;9:393-402. Epub 2017 Jul 31.
    Research Centre for Prevention and Health, Capital Region of Denmark, Glostrup.
    Objective: Irritable bowel syndrome (IBS) is associated with mental vulnerability, and half of patients report comorbid somatic and mental symptoms. We aimed to investigate the relationship between an IBS symptom continuum and the subsequent development of common mental disorders (CMDs) and functional somatic syndromes (FSSs).

    Methods And Study Design: A longitudinal population-based study comprising two 5-year follow-up studies, Dan-MONICA 1 (1982-1987) and Inter99 (1999-2004), recruited from the western part of Copenhagen County. Read More

    Incidence, clinical presentation, and outcome of HIV-1-associated cryptococcal meningitis during the highly active antiretroviral therapy era: a nationwide cohort study.
    Clin Epidemiol 2017 21;9:385-392. Epub 2017 Jul 21.
    Department of Infectious Diseases, Rigshospitalet, Copenhagen University Hospital, Copenhagen.
    Background: Human immunodeficiency virus (HIV) infection with advanced immunosuppression predisposes to cryptococcal meningitis (CM). We describe the incidence, clinical presentation, and outcome of CM in HIV-infected individuals during the highly active antiretroviral therapy (HAART) era.

    Methods: A nationwide, population-based cohort of HIV-infected individuals was used to estimate incidence and mortality of CM including risk factors. Read More

    Fecal occult blood versus DNA testing: indirect comparison in a colorectal cancer screening population.
    Clin Epidemiol 2017 13;9:377-384. Epub 2017 Jul 13.
    Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ).
    Background: A multitarget stool DNA test (MSDT) that showed higher sensitivity but lower specificity than a fecal immunochemical test (FIT) for hemoglobin in one recent study from the US and Canada, is increasingly used for colorectal cancer (CRC) screening, despite its ~20-fold higher costs compared to FITs. We aimed to assess diagnostic performance of a quantitative FIT in an independent study among participants of screening colonoscopy and to compare it with the previously reported performance of MSDT.

    Methods: A total of 3494 participants, aged 50-84 years, who underwent screening colonoscopy in private gastroenterological practices in Germany, and who provided a stool sample before colonoscopy to be evaluated by a commercially available quantitative FIT (FOB Gold(®)) were included. Read More

    Validity of an automated algorithm using diagnosis and procedure codes to identify decompensated cirrhosis using electronic health records.
    Clin Epidemiol 2017 12;9:369-376. Epub 2017 Jul 12.
    Division of Gastroenterology and Hepatology, Henry Ford Health System, Detroit, MI, USA.
    Viral hepatitis-induced cirrhosis can progress to decompensated cirrhosis. Clinical decompensation represents a milestone event for the patient with cirrhosis, yet there remains uncertainty regarding precisely how to define this important phenomenon. With the development of broader treatment options for cirrhotic hepatitis patients, efficient identification of liver status before evolving to decompensated cirrhosis could be life-saving, but research on the topic has been limited by inconsistencies across studies, populations, and case-confirmation methods. Read More

    The criterion validity of the web-based Major Depression Inventory when used on clinical suspicion of depression in primary care.
    Clin Epidemiol 2017 6;9:355-365. Epub 2017 Jul 6.
    Research Unit for General Practice, Department of Public Health, Aarhus University.
    Background: The Major Depression Inventory (MDI) is widely used in Danish general practice as a screening tool to assess depression in symptomatic patients. Nevertheless, no validation studies of the MDI have been performed. The aim of this study was to validate the web-based version of the MDI against a fully structured telephone interview in a population selected on clinical suspicion of depression (ie, presence of two or three core symptoms of depression) in general practice. Read More

    Sociodemographic characteristics of nonparticipants in the Danish colorectal cancer screening program: a nationwide cross-sectional study.
    Clin Epidemiol 2017 27;9:345-354. Epub 2017 Jun 27.
    Department of Public Health Programmes, Randers Regional Hospital, Central Denmark Region, Randers NO.
    Introduction: Fecal occult blood tests are recommended for colorectal cancer (CRC) screening in Europe. Recently, the fecal immunochemical test (FIT) has come into use. Sociodemographic differences between participants and nonparticipants may be less pronounced when using FIT as there are no preceding dietary restrictions and only one specimen is required. Read More

    Prevalence of hypercalcemia of malignancy among pediatric cancer patients in the UK Clinical Practice Research Datalink database.
    Clin Epidemiol 2017 15;9:339-343. Epub 2017 Jun 15.
    Center for Observational Research, Amgen Inc., Thousand Oaks and South San Francisco, CA, USA.
    Background: The reported proportion of cancer patients who experience hypercalcemia of malignancy (HCM) is low, particularly in the pediatric population, ranging between <1% and 5%. HCM can be observed with any type of tumor in children and occurs most commonly with leukemia. While HCM is a potentially fatal condition, the prevalence of HCM is not well understood in pediatric cancer patients. Read More

    Effect modification, interaction and mediation: an overview of theoretical insights for clinical investigators.
    Clin Epidemiol 2017 8;9:331-338. Epub 2017 Jun 8.
    Department of Clinical Epidemiology, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.
    We revisited the three interrelated epidemiological concepts of effect modification, interaction and mediation for clinical investigators and examined their applicability when using research databases. The standard methods that are available to assess interaction, effect modification and mediation are explained and exemplified. For each concept, we first give a simple "best-case" example from a randomized controlled trial, followed by a structurally similar example from an observational study using research databases. Read More

    Return to work for patients with diffuse large B-cell lymphoma and transformed indolent lymphoma undergoing autologous stem cell transplantation.
    Clin Epidemiol 2017 6;9:321-329. Epub 2017 Jun 6.
    Department of Hematology, Copenhagen University Hospital, Rigshospitalet.
    Background: Autologous stem cell transplantation (ASCT) is the standard treatment for patients with relapsed diffuse large B-cell lymphoma (DLBCL) or transformed indolent lymphoma (TIL). The treatment is mainly considered for younger patients still available for the work market. In this study, social outcomes after ASCT in terms of return to work (RTW) are described. Read More

    Charlson comorbidity index derived from chart review or administrative data: agreement and prediction of mortality in intensive care patients.
    Clin Epidemiol 2017 2;9:311-320. Epub 2017 Jun 2.
    Department of Anaesthesiology, Surgical Division, Akershus University Hospital, Lørenskog, Norway.
    Purpose: This study compared the Charlson comorbidity index (CCI) information derived from chart review and administrative systems to assess the completeness and agreement between scores, evaluate the capacity to predict 30-day and 1-year mortality in intensive care unit (ICU) patients, and compare the predictive capacity with that of the Simplified Acute Physiology Score (SAPS) II model.

    Patients And Methods: Using data from 959 patients admitted to a general ICU in a Norwegian university hospital from 2007 to 2009, we compared the CCI score derived from chart review and administrative systems. Agreement was assessed using % agreement, kappa, and weighted kappa. Read More

    Transmission of health care-associated infections from roommates and prior room occupants: a systematic review.
    Clin Epidemiol 2017 23;9:297-310. Epub 2017 May 23.
    Columbia University School of Nursing, New York, NY, USA.
    Pathogens that cause health care-associated infections (HAIs) are known to survive on surfaces and equipment in health care environments despite routine cleaning. As a result, the infection status of prior room occupants and roommates may play a role in HAI transmission. We performed a systematic review of the literature evaluating the association between patients' exposure to infected/colonized hospital roommates or prior room occupants and their risk of infection/colonization with the same organism. Read More

    Hypoglycemia: a review of definitions used in clinical trials evaluating antihyperglycemic drugs for diabetes.
    Clin Epidemiol 2017 23;9:291-296. Epub 2017 May 23.
    Department of Health Research Methods, Evidence, and Impact, Faculty of Health Sciences, McMaster University, Hamilton, ON, Canada.
    Objective: To understand the severity and potential impact of heterogeneity in definitions of hypoglycemia used in diabetes research, we aimed to review the hypoglycemia definitions adopted in randomized controlled trials (RCTs).

    Methods: We reviewed 109 RCTs included in the Canadian Agency for Drugs and Technologies in Health reports for the second- and third-line therapy for the patients with type 2 diabetes (T2D).

    Results: Nearly 60% (n=66) of the studies reviewed presented the definitions for overall hypoglycemia, and another 20% (n=22) of the studies reported the results for hypoglycemia but did not report a definition. Read More

    The impact of socioeconomic status and multimorbidity on mortality: a population-based cohort study.
    Clin Epidemiol 2017 10;9:279-289. Epub 2017 May 10.
    Research Unit for General Practice.
    Objective: Multimorbidity (MM) is more prevalent among people of lower socioeconomic status (SES), and both MM and SES are associated with higher mortality rates. However, little is known about the relationship between SES, MM, and mortality. This study investigates the association between educational level and mortality, and to what extent MM modifies this association. Read More

    Use of the Medicare database in epidemiologic and health services research: a valuable source of real-world evidence on the older and disabled populations in the US.
    Clin Epidemiol 2017 9;9:267-277. Epub 2017 May 9.
    Chronic Disease Research Group, Minneapolis, MN, USA.
    Medicare is the federal health insurance program for individuals in the US who are aged ≥65 years, select individuals with disabilities aged <65 years, and individuals with end-stage renal disease. The Centers for Medicare and Medicaid Services grants researchers access to Medicare administrative claims databases for epidemiologic and health outcomes research. The data cover beneficiaries' encounters with the health care system and receipt of therapeutic interventions, including medications, procedures, and services. Read More

    Positive predictive value of peptic ulcer diagnosis codes in the Danish National Patient Registry.
    Clin Epidemiol 2017 5;9:261-266. Epub 2017 May 5.
    Department of Clinical Epidemiology.
    Background: Diagnoses of peptic ulcer are registered in the Danish National Patient Registry (DNPR) for administrative as well as research purposes, but it is unknown whether the coding validity depends on the location of the ulcer.

    Objective: To validate the International Classification of Diseases, 10(th) revision diagnosis codes of peptic ulcer in the DNPR by estimating positive predictive values (PPVs) for gastric and duodenal ulcer diagnoses.

    Methods: We identified all patients registered with a hospital discharge diagnosis of peptic ulcer from Aarhus University Hospital, Denmark, in 1995-2006. Read More

    Prevalence and prognosis of stress disorders: a review of the epidemiologic literature.
    Clin Epidemiol 2017 3;9:251-260. Epub 2017 May 3.
    National Center for PTSD, VA Boston Healthcare System.
    Given the ubiquity of traumatic events, it is not surprising that posttraumatic stress disorder (PTSD) - a common diagnosis following one of these experiences - is characterized as conferring a large burden for individuals and society. Although there is recognition of the importance of PTSD diagnoses throughout psychiatry, the literature on other diagnoses one may receive following a stressful or traumatic event is scant. This review summarizes the literature on stress disorders (classified according to the International Classification of Diseases, 10th Edition [ICD-10]), including acute stress reaction, PTSD, adjustment disorder and unspecified stress reactions. Read More

    Clinical epidemiology in the era of big data: new opportunities, familiar challenges.
    Clin Epidemiol 2017 27;9:245-250. Epub 2017 Apr 27.
    Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, Denmark.
    Routinely recorded health data have evolved from mere by-products of health care delivery or billing into a powerful research tool for studying and improving patient care through clinical epidemiologic research. Big data in the context of epidemiologic research means large interlinkable data sets within a single country or networks of multinational databases. Several Nordic, European, and other multinational collaborations are now well established. Read More

    Cardiovascular risks in smokers treated with nicotine replacement therapy: a historical cohort study.
    Clin Epidemiol 2017 26;9:231-243. Epub 2017 Apr 26.
    Observational and Pragmatic Research Institute Pte Ltd, Singapore.
    Background: Previous research suggests exposure to nicotine replacement therapy (NRT) may be associated with an increased risk of cardiovascular disease (CVD).

    Methods: Using data from the United Kingdom's Clinical Practice Research Datalink, this study aimed to evaluate CVD events and survival among individuals who attempted smoking cessation with the support of NRT compared with those aided by smoking cessation advice only. We studied CVD outcomes over 4 and 52 weeks in 50,214 smokers attempting to quit - 33,476 supported by smoking cessation advice and 16,738 with the support of NRT prescribed by their primary care physician. Read More

    Effect of glomerular filtration rate at dialysis initiation on survival in patients with advanced chronic kidney disease: what is the effect of lead-time bias?
    Clin Epidemiol 2017 10;9:217-230. Epub 2017 Apr 10.
    Department of Clinical Epidemiology, Leiden University Medical Center, Leiden.
    Purpose: Current clinical guidelines recommend to initiate dialysis in the presence of symptoms or signs attributable to kidney failure, often with a glomerular filtration rate (GFR) of 5-10 mL/min/1.73 m(2). Little evidence exists about the optimal kidney function to start dialysis. Read More

    The association between thyroid disorders and incident gout: population-based case-control study.
    Clin Epidemiol 2017 6;9:205-215. Epub 2017 Apr 6.
    Basel Pharmacoepidemiology Unit, Division of Clinical Pharmacy and Epidemiology, Department of Pharmaceutical Sciences, University of Basel.
    Context: Thyroid hormones influence kidney function and thereby might alter serum urate levels, a major risk factor for gouty arthritis.

    Objective: To assess the risk of developing incident gout in association with hypothyroidism or hyperthyroidism.

    Design: Retrospective population-based case-control analysis. Read More

    Control of confounding in the analysis phase - an overview for clinicians.
    Clin Epidemiol 2017 31;9:195-204. Epub 2017 Mar 31.
    Department of Clinical Epidemiology, Institute of Clinical Medicine.
    In observational studies, control of confounding can be done in the design and analysis phases. Using examples from large health care database studies, this article provides the clinicians with an overview of standard methods in the analysis phase, such as stratification, standardization, multivariable regression analysis and propensity score (PS) methods, together with the more advanced high-dimensional propensity score (HD-PS) method. We describe the progression from simple stratification confined to the inclusion of a few potential confounders to complex modeling procedures such as the HD-PS approach by which hundreds of potential confounders are extracted from large health care databases. Read More

    Confounding in observational studies based on large health care databases: problems and potential solutions - a primer for the clinician.
    Clin Epidemiol 2017 28;9:185-193. Epub 2017 Mar 28.
    Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark; Department of Clinical Epidemiology, Leiden University Medical Center, The Netherlands; Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom.
    Population-based health care databases are a valuable tool for observational studies as they reflect daily medical practice for large and representative populations. A constant challenge in observational designs is, however, to rule out confounding, and the value of these databases for a given study question accordingly depends on completeness and validity of the information on confounding factors. In this article, we describe the types of potential confounding factors typically lacking in large health care databases and suggest strategies for confounding control when data on important confounders are unavailable. Read More

    Positive predictive values of International Classification of Diseases, 10th revision codes for dermatologic events and hypersensitivity leading to hospitalization or emergency room visit among women with postmenopausal osteoporosis in the Danish and Swedish national patient registries.
    Clin Epidemiol 2017 24;9:179-184. Epub 2017 Mar 24.
    Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, Denmark.
    Background: Clinical epidemiology research studies, including pharmacoepidemiology and pharmacovigilance studies, use routinely collected health data, such as diagnoses recorded in national health and administrative registries, to assess clinical effectiveness and safety of treatments. We estimated positive predictive values (PPVs) of International Classification of Diseases, 10th revision (ICD-10) codes for primary diagnoses of dermatologic events and hypersensitivity recorded at hospitalization or emergency room visit in the national patient registries of Denmark and Sweden among women with postmenopausal osteoporosis (PMO).

    Methods: This validation study included women with PMO identified from the Danish and Swedish national patient registries (2005-2014). Read More

    Chinese health care system and clinical epidemiology.
    Clin Epidemiol 2017 16;9:167-178. Epub 2017 Mar 16.
    Key Laboratory of Reproduction Regulation of NPFPC, SIPPR, IRD, Fudan University, Shanghai, People's Republic of China.
    China has gone through a comprehensive health care insurance reform since 2003 and achieved universal health insurance coverage in 2011. The new health care insurance system provides China with a huge opportunity for the development of health care and medical research when its rich medical resources are fully unfolded. In this study, we review the Chinese health care system and its implication for medical research, especially within clinical epidemiology. Read More

    Missing data and multiple imputation in clinical epidemiological research.
    Clin Epidemiol 2017 15;9:157-166. Epub 2017 Mar 15.
    Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus N, Denmark; Department of Primary Care and Population Health, University College London, London, UK.
    Missing data are ubiquitous in clinical epidemiological research. Individuals with missing data may differ from those with no missing data in terms of the outcome of interest and prognosis in general. Missing data are often categorized into the following three types: missing completely at random (MCAR), missing at random (MAR), and missing not at random (MNAR). Read More

    The completeness of chest X-ray procedure codes in the Danish National Patient Registry.
    Clin Epidemiol 2017 6;9:151-156. Epub 2017 Mar 6.
    Research Center for Cancer Diagnosis in Primary Care, Department of Public Health; University Clinic for Innovative Health Care Delivery, Diagnostic Centre, Silkeborg Hospital, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.
    Objective: The aim of this validation study was to assess the completeness of the registrations of chest X-rays (CXR) in two different versions of the Danish National Patient Registry (DNPR).

    Material And Methods: We included electronic record data on CXR performed on patients aged 40 to 99 years from nine radiology departments covering 20 Danish hospitals. From each department, we included data from three randomly selected weeks between 2004 and 2011 (reference standard). Read More

    A nationwide population-based cross-sectional survey of health-related quality of life in patients with myeloproliferative neoplasms in Denmark (MPNhealthSurvey): survey design and characteristics of respondents and nonrespondents.
    Clin Epidemiol 2017 2;9:141-150. Epub 2017 Mar 2.
    Danish Knowledge Centre for Rehabilitation and Palliative Care, University of Southern Denmark and Odense University Hospital, Odense, Denmark.
    Objective: The Department of Hematology, Zealand University Hospital, Denmark, and the National Institute of Public Health, University of Southern Denmark, created the first nationwide, population-based, and the most comprehensive cross-sectional health-related quality of life (HRQoL) survey of patients with myeloproliferative neoplasms (MPNs). In Denmark, all MPN patients are treated in public hospitals and treatments received are free of charge for these patients. Therefore, MPN patients receive the best available treatment to the extent of its suitability for them and if they wish to receive the treatment. Read More

    Cohort description: The Danish study of Functional Disorders.
    Clin Epidemiol 2017 23;9:127-139. Epub 2017 Feb 23.
    Research Centre for Prevention and Health, The Capital Region of Denmark, Glostrup; Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen; Faculty of Medicine, Aalborg University, Aalborg, Denmark.
    The Danish study of Functional Disorders (DanFunD) cohort was initiated to outline the epidemiology of functional somatic syndromes (FSS) and is the first larger coordinated epidemiological study focusing exclusively on FSS. FSS are prevalent in all medical settings and can be defined as syndromes that, after appropriate medical assessment, cannot be explained in terms of a conventional medical or surgical disease. FSS are frequent and the clinical importance varies from vague symptoms to extreme disability. Read More

    The clinical impact of serrated colorectal polyps.
    Clin Epidemiol 2017 22;9:113-125. Epub 2017 Feb 22.
    Division of Gastroenterology and Hepatology, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
    Serrated polyps (SPs) of the colorectum pose a novel challenge to practicing gastroenterologists. Previously thought benign and unimportant, there is now compelling evidence that SPs are responsible for a significant percentage of incident colorectal cancer worldwide. In contrast to conventional adenomas, which tend to be slow growing and polypoid, SPs have unique features that undermine current screening and surveillance practices. Read More

    Validity of data in the Danish Colorectal Cancer Screening Database.
    Clin Epidemiol 2017 17;9:105-111. Epub 2017 Feb 17.
    Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus.
    Background: In Denmark, a nationwide screening program for colorectal cancer was implemented in March 2014. Along with this, a clinical database for program monitoring and research purposes was established.

    Objective: The aim of this study was to estimate the agreement and validity of diagnosis and procedure codes in the Danish Colorectal Cancer Screening Database (DCCSD). Read More

    Antiepileptic drugs prescribed in pregnancy and prevalence of major congenital malformations: comparative prevalence studies.
    Clin Epidemiol 2017 16;9:95-103. Epub 2017 Feb 16.
    Department of Primary Care and Population Health, University College London, London, UK.
    Objective: The aim of this study was to examine the prevalence of major congenital malformations associated with antiepileptic drug (AED) treatment in pregnancy.

    Patients And Methods: Using data from The Health Improvement Network, we identified women who have given live birth and their offspring. Four subgroups were selected based on the AED treatment in early pregnancy, valproate, carbamazepine, lamotrigine and women not receiving AED treatment. Read More

    Risk of gynecomastia and breast cancer associated with the use of 5-alpha reductase inhibitors for benign prostatic hyperplasia.
    Clin Epidemiol 2017 10;9:83-91. Epub 2017 Feb 10.
    Boston Collaborative Drug Surveillance Program, Boston University School of Public Health, Lexington.
    Background: Clinical trial results suggest that 5-alpha reductase inhibitors (5ARIs) for the treatment of benign prostatic hyperplasia (BPH) may increase the risk of gynecomastia and male breast cancer, but epidemiological studies have been limited.

    Patients And Methods: We conducted a cohort study with nested case-control analyses using the UK Clinical Practice Research Datalink. We identified men diagnosed with BPH who were free from Klinefelter syndrome, prostate, genital or urinary cancer, prostatectomy or orchiectomy, or evidence of gynecomastia or breast cancer. Read More

    Evaluation of ICD-10 algorithms to identify hypopituitary patients in the Danish National Patient Registry.
    Clin Epidemiol 2017 9;9:75-82. Epub 2017 Feb 9.
    Department of Endocrinology and Internal Medicine; Department of Pediatrics, Center of Rare Diseases, Aarhus University Hospital, Aarhus, Denmark.
    Objective: Routinely collected health data may be valuable sources for conducting research. This study aimed to evaluate the validity of algorithms detecting hypopituitary patients in the Danish National Patient Registry (DNPR) using medical records as reference standard.

    Study Design And Setting: Patients with International Classification of Diseases (10th edition [ICD-10]) diagnoses of hypopituitarism, or other diagnoses of pituitary disorders assumed to be associated with an increased risk of hypopituitarism, recorded in the DNPR during 2000-2012 were identified. Read More

    Clinical validation of immunoglobulin A nephropathy diagnosis in Swedish biopsy registers.
    Clin Epidemiol 2017 31;9:67-73. Epub 2017 Jan 31.
    Department of Pediatrics, Örebro University Hospital, Örebro; Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; Division of Epidemiology and Public Health, School of Medicine, University of Nottingham, Nottingham, UK.
    Aims: The aims of this study were to validate the diagnosis of IgA nephropathy (IgAN) in Swedish biopsy registers against patient charts and to describe the clinical characteristics of patients with a biopsy indicating IgAN.

    Methods: This is a population-based cohort study. Out of 4,069 individuals with a renal biopsy consistent with IgAN (biopsies performed in 1974-2011), this study reviewed patient charts of a random subset of 127 individuals. Read More

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