Case-control confusion

Objective: Critical analysis of journal articles by using principles of evidence-based medicine is important for clinicians applying research results in their practice and is a valuable component of pediatric residency training. Appraisal of an article's methodological rigor is often tailored to a particular type of study design, so that misclassification of study design can confuse the appraisal. The goal of this study was to determine how often pediatric research articles that are self-declared as casecontrol studies conform to a standard definition for this study design. Methods: A Medline search identified articles published in two pediatric journals from January 1996 through August 2004 with the phrase "case-control study" in the title or abstract. Articles that were self-declared as case-control studies were analyzed to determine whether they satisfied a standard definition of a casecontrol study. Results: Of the 91 purported case-control studies, only 68 (75%) met the standard definition for at least the most important analysis. The remaining 23 articles could be classified as crosssectional studies (N = 16) or prospective cohort studies (N = 7). Conclusions: Ambiguity in the definition of a case-control study can cause confusion in the critical appraisal of published clinical research.