Research Topics
| R H H GroenwoldSummaryAffiliation: University Medical Center Utrecht Country: The Netherlands Publications
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Detail Information
Publications
[Case-control study: the importance of selecting the right controls]Rolf H H Groenwold
Universitair Medisch Centrum Utrecht, Julius Centrum voor Gezondheidswetenschappen en Eerstelijns Gezondheidszorg, Utrecht, The Netherlands
Ned Tijdschr Geneeskd 157:A5697. 2013..We illustrate the case-control study design by an example study into the relation between mobile phone use and the risk of traffic accidents, with a focus on the selection of controls...
Progestogens to prevent preterm birth in twin pregnancies: an individual participant data meta-analysis of randomized trialsEwoud Schuit
Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, Utrecht, The Netherlands
BMC Pregnancy Childbirth 12:13. 2012....
[Bias in observational research: 'confounding']Rolf H H Groenwold
Julius Centrum voor Gezondheidswetenschappen en Eerstelijns Gezondheidszorg, Universitair Medisch Centrum Utrecht, Utrecht, The Netherlands
Ned Tijdschr Geneeskd 156:A4221. 2012..Research in the area of confounding is currently directed at the incorporation of external knowledge on unmeasured confounders, the evaluation of instrumental variables, and the impact of time-dependent confounding...
Dealing with missing outcome data in randomized trials and observational studiesRolf H H Groenwold
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, The Netherlands
Am J Epidemiol 175:210-7. 2012..Multiple imputation, in addition, can accommodate the missing-not-at-random scenario more flexibly, making it especially suited for sensitivity analyses...
Balance measures for propensity score methods: a clinical example on beta-agonist use and the risk of myocardial infarctionRolf H H Groenwold
Department of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Utrecht, The Netherlands
Pharmacoepidemiol Drug Saf 20:1130-7. 2011..Our objective was to compare balance measures in clinical data and assessed the association between long-acting inhalation beta-agonist (LABA) use and myocardial infarction...
Selection of confounding variables should not be based on observed associations with exposureRolf H H Groenwold
Department of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, The Netherlands
Eur J Epidemiol 26:589-93. 2011..80-1.26). Confounding variables should not be discarded based on balanced distributions among exposure groups, because residual confounding due to the omission of confounding variables from the adjustment model can be relevant...
Reporting of treatment effects from randomized trials: a plea for multivariable risk ratiosRolf H H Groenwold
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands
Contemp Clin Trials 32:399-402. 2011..When odds ratios are used, adjustment for baseline covariates should be considered, also when these are well-balanced between the treatment groups...
Confounding in publications of observational intervention studiesRolf H H Groenwold
Julius Center for Health Sciences and Primary Care, University Medical Center, Universiteitsweg 100, STR 6 118, 3584 GC, Utrecht, The Netherlands
Eur J Epidemiol 22:413-5. 2007..This study shows only 9% of all papers on observational intervention studies published in peer-reviewed medical journals mention any of the terms (confounding, adjustment, or bias) indicating appreciation of confounding...
Subgroup effects despite homogeneous heterogeneity test resultsRolf H H Groenwold
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands
BMC Med Res Methodol 10:43. 2010..Lack of demonstrable statistical heterogeneity, however, might obscure clinical heterogeneity, meaning clinically relevant subgroup effects...
Sensitivity analyses to estimate the potential impact of unmeasured confounding in causal researchRolf H H Groenwold
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands
Int J Epidemiol 39:107-17. 2010..Although several sensitivity analyses are available, these are used infrequently. This article is intended as a tutorial on sensitivity analyses, in which we discuss three methods to conduct sensitivity analysis...
Instrumental variables in influenza vaccination studies: mission impossible?!Rolf H H Groenwold
Julius Center for Health Sciences and Primary Care, Department of Epidemiology, University Medical Center Utrecht, Utrecht, The Netherlands
Value Health 13:132-7. 2010..Theoretically, analyses using IVs to control for both observed and unobserved confounding may provide unbiased estimates of influenza vaccine effects. We assessed the usefulness of IV analysis in influenza vaccination studies...
Quantitative assessment of unobserved confounding is mandatory in nonrandomized intervention studiesR H H Groenwold
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, The Netherlands
J Clin Epidemiol 62:22-8. 2009..Our objective was to review methods to control for observed confounding, as well as unobserved confounding..
Pooling of confounders did not induce residual confounding in influenza vaccination studiesRolf H H Groenwold
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, The Netherlands
Ann Epidemiol 19:432-6. 2009..It has been suggested, however, that the pooling of confounders induces residual confounding, although empirical evidence is scarce. We set out to study the effects of combining several confounders into classes of co-morbidity...
Impact of influenza vaccination on mortality risk among the elderlyR H H Groenwold
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, P O Box 85500, 3508 GA, Utrecht, The Netherlands
Eur Respir J 34:56-62. 2009..After taking unmeasured confounding into account, influenza vaccination is still associated with substantial reduction in mortality risk...
Poor quality of reporting confounding bias in observational intervention studies: a systematic reviewRolf H H Groenwold
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, The Netherlands
Ann Epidemiol 18:746-51. 2008..To systematically review observational studies on medical interventions to determine the quality of reporting of confounding...
Quantifying the potential role of unmeasured confounders: the example of influenza vaccinationR H H Groenwold
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, The Netherlands
Int J Epidemiol 37:1422-9. 2008....
How to deal with measures of association: a short guide for the clinicianM J Knol
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands
Cerebrovasc Dis 33:98-103. 2012..By means of examples, we will discuss the different measures of association for the three main study designs used in clinical research: randomized controlled trial, observational cohort study and case-control study...
Cause-specific long-term mortality rates in patients recovered from community-acquired pneumonia as compared with the general Dutch populationA H W Bruns
Department of Internal Medicine and Infectious Diseases, Division of Medicine, University Medical Centre, Utrecht, The Netherlands
Clin Microbiol Infect 17:763-8. 2011..After an episode of CAP, optimization of treatment of comorbidities, such as treatment for COPD, might improve long-term survival rates...
Association between cannabis and psychiatric hospitalizationC D Schubart
Rudolf Magnus Institute of Neuroscience, Department of Psychiatry, University Medical Center, Utrecht, The Netherlands
Acta Psychiatr Scand 123:368-75. 2011..To investigate the relationship between cannabis use and mental health...
