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Clinical Epidemiology

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https://www.readbyqxmd.com/read/28408854/control-of-confounding-in-the-analysis-phase-an-overview-for-clinicians
#1
Johnny Kahlert, Sigrid Bjerge Gribsholt, Henrik Gammelager, Olaf M Dekkers, George Luta
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...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28405173/confounding-in-observational-studies-based-on-large-health-care-databases-problems-and-potential-solutions-a-primer-for-the-clinician
#2
Mette Nørgaard, Vera Ehrenstein, Jan P Vandenbroucke
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...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28392715/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
#3
Kasper Adelborg, Lotte Brix Christensen, Troels Munch, Johnny Kahlert, Ylva Trolle Lagerros, Grethe S Tell, Ellen M Apalset, Fei Xue, Vera Ehrenstein
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)...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28356772/chinese-health-care-system-and-clinical-epidemiology
#4
REVIEW
Yuelian Sun, Hans Gregersen, Wei Yuan
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. First, we briefly review the population register system, the distribution of the urban and rural population in China, and the development of the Chinese health care system after 1949...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28352203/missing-data-and-multiple-imputation-in-clinical-epidemiological-research
#5
Alma B Pedersen, Ellen M Mikkelsen, Deirdre Cronin-Fenton, Nickolaj R Kristensen, Tra My Pham, Lars Pedersen, Irene Petersen
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). In clinical epidemiological research, missing data are seldom MCAR. Missing data can constitute considerable challenges in the analyses and interpretation of results and can potentially weaken the validity of results and conclusions...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28293121/the-completeness-of-chest-x-ray-procedure-codes-in-the-danish-national-patient-registry
#6
Peter Hjertholm, Kaare Rud Flarup, Louise Mahncke Guldbrandt, Peter Vedsted
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)...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28280390/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
#7
Nana Brochmann, Esben Meulengracht Flachs, Anne Illemann Christensen, Christen Lykkegaard Andersen, Knud Juel, Hans Carl Hasselbalch, Ann-Dorthe Zwisler
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...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28275316/cohort-description-the-danish-study-of-functional-disorders
#8
Thomas Meinertz Dantoft, Jeanette Frost Ebstrup, Allan Linneberg, Sine Skovbjerg, Anja Lykke Madsen, Jesper Mehlsen, Louise Brinth, Lene Falgaard Eplov, Tina Wisbech Carstensen, Andreas Schroder, Per Klausen Fink, Erik Lykke Mortensen, Torben Hansen, Oluf Pedersen, Torben Jørgensen
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...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28260946/the-clinical-impact-of-serrated-colorectal-polyps
#9
REVIEW
Brendon M O'Connell, Seth D Crockett
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. For example, sessile serrated polyps (SSPs) are flat, predominately right-sided, and thought to have the potential for rapid growth...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28255255/validity-of-data-in-the-danish-colorectal-cancer-screening-database
#10
Mette Kielsholm Thomsen, Sisse Helle Njor, Morten Rasmussen, Dorte Linnemann, Berit Andersen, Gunnar Baatrup, Lennart Jan Friis-Hansen, Jens Christian Riis Jørgensen, Ellen Margrethe Mikkelsen
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). METHODS: All individuals with a positive immunochemical fecal occult blood test (iFOBT) result who were invited to screening in the first 3 months since program initiation were identified...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28243149/antiepileptic-drugs-prescribed-in-pregnancy-and-prevalence-of-major-congenital-malformations-comparative-prevalence-studies
#11
Irene Petersen, Shuk-Li Collings, Rachel L McCrea, Irwin Nazareth, David P Osborn, Phil J Cowen, Cormac J Sammon
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. We compared the prevalence of major congenital malformations within children of these four groups and estimated prevalence ratios (PRs) using Poisson regression adjusted for maternal age, sex of child, quintiles of Townsend deprivation score and indication for treatment...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28243148/challenges-for-a-successful-career-as-a-phd-student
#12
Ana Luiza Zaninotto, Tatiana Saito Paiva, Marcia André, Beatriz Silva Mattos, Wellingson Silva Paiva
No abstract text is available yet for this article.
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28228662/risk-of-gynecomastia-and-breast-cancer-associated-with-the-use-of-5-alpha-reductase-inhibitors-for-benign-prostatic-hyperplasia
#13
Katrina Wilcox Hagberg, Hozefa A Divan, Shona C Fang, J Curtis Nickel, Susan S Jick
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...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28223847/evaluation-of-icd-10-algorithms-to-identify-hypopituitary-patients-in-the-danish-national-patient-registry
#14
Agnethe Berglund, Morten Olsen, Marianne Andersen, Eigil Husted Nielsen, Ulla Feldt-Rasmussen, Caroline Kistorp, Claus Højbjerg Gravholt, Kirstine Stochhholm
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...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28203107/clinical-validation-of-immunoglobulin-a-nephropathy-diagnosis-in-swedish-biopsy-registers
#15
Simon Jarrick, Sigrid Lundberg, Adina Welander, C Michael Fored, Jonas F Ludvigsson
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. Clinical and biopsy characteristics at the time of biopsy were evaluated, and positive predictive values (PPV) were calculated with 95% confidence intervals (CI)...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28182159/incidence-type-of-atrial-fibrillation-and-risk-factors-for-stroke-a-population-based-cohort-study
#16
Cecilia Johansson, Erik Dahlqvist, Jonas Andersson, Jan-Håkan Jansson, Lars Johansson
PURPOSE: The aims of this study were to estimate the incidence of atrial fibrillation and atrial flutter (AF), to assess the presence of provoking factors and risk factors for stroke and systemic embolism, and to determine the type of AF in patients with first-diagnosed AF. PATIENTS AND METHODS: This cohort study was performed in northern Sweden between January 1, 2011 and December 31, 2012. Diagnosis registries were searched for the International Classification of Diseases-10 code for AF (I48) to identify cases of incident AF...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28182137/comment-on-an-algorithm-for-identification-and-classification-of-individuals-with-type-1-and-type-2-diabetes-mellitus-in-a-large-primary-care-database-written-by-sharma-et-al
#17
https://www.readbyqxmd.com/read/28176979/risk-of-pneumonia-and-urinary-tract-infection-within-the-first-week-after-total-hip-arthroplasty-and-the-impact-on-survival
#18
Eva N Glassou, Torben B Hansen, Alma B Pedersen
BACKGROUND: Pneumonia and urinary tract infections (UTIs) increase morbidity and mortality. There is little epidemiological evidence from large population-based studies on risk factors for these infections and subsequent mortality in total hip arthroplasty (THA) patients. AIM: To examine the risk factors of postoperative pneumonia and UTI after THA and their impact on survival. PATIENTS AND METHODS: We used the Danish Hip Arthroplasty Register to identify THAs due to osteoarthritis registered from 2000 to 2013...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28176959/a-systematic-literature-review-on-the-efficacy-effectiveness-gap-comparison-of-randomized-controlled-trials-and-observational-studies-of-glucose-lowering-drugs
#19
REVIEW
Mikkel Z Ankarfeldt, Erpur Adalsteinsson, Rolf Hh Groenwold, M Sanni Ali, Olaf H Klungel
AIM: To identify a potential efficacy-effectiveness gap and possible explanations (drivers of effectiveness) for differences between results of randomized controlled trials (RCTs) and observational studies investigating glucose-lowering drugs. METHODS: A systematic literature review was conducted in English language articles published between 1 January, 2000 and 31 January, 2015 describing either RCTs or observational studies comparing glucagon-like peptide-1 analogs (GLP-1) with insulin or comparing dipeptidyl peptidase-4 inhibitors (DPP-4i) with sulfonylurea, all with change in glycated hemoglobin (HbA1c) as outcome...
2017: Clinical Epidemiology
https://www.readbyqxmd.com/read/28176886/assessment-of-channeling-bias-among-initiators-of-glucose-lowering-drugs-a-uk-cohort-study
#20
Mikkel Z Ankarfeldt, Brian L Thorsted, Rolf Hh Groenwold, Erpur Adalsteinsson, M Sanni Ali, Olaf H Klungel
BACKGROUND: Channeling bias may occur when a newly marketed drug and an established drug, despite similar indications, are prescribed to patients with different prognostic characteristics (ie, confounding). AIM: To investigate channeling bias and its impact on relative effectiveness of glucagon-like peptide-1 (GLP-1) analogs versus basal insulin and dipeptidyl peptidase-4 inhibitors (DPP-4i) versus sulfonylurea. METHODS: In the UK Clinical Practice Research Datalink, patients with type 2 diabetes initiating treatment between 2006 and 2015 were included...
2017: Clinical Epidemiology
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