Objective: Critical appraisal of published case-control studies examining the etiology or risk factors of Hyperemesis gravidarum (HG).
Materials and methods: We searched the Medline/PubMed database from 1966 to February 12, 2009. A total of 48 case-control studies were retrieved and each article was evaluated using a structured assessment devised for the purpose.
Results: The case-control studies were published between 1978 and 2008. The majority investigated hormonal, gastrointestinal, and metabolic risk factors associated with hyperemesis gravidarum (37 studies). Selection bias and non-response received insufficient attention in many articles. Sample size varied widely with a median number of 40 cases and 42 controls. Association uncommonly was expressed by odds ratios and confidence intervals (9 studies), confounding rarely controlled for (10 studies) and few examined effect modification (2 studies).
Conclusion: We are concerned as far the inadequacies in the design, analysis, and reporting of case-control studies examining the etiology of HG. It is mandatory to follow adequate clinical research methodology in executing and reporting such studies.