Critical appraisal of case-control studies of risk factors or etiology of Hyperemesis gravidarum.
OBJECTIVE
Critical appraisal of published case-control studies examining the etiology or risk factors of Hyperemesis gravidarum (HG).


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).


CONCLUSIONS
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.
Sandven
Irene
I
Unit of Epidemiology and Biostatistics, Ullevaal Centre of Clinical Research, Oslo University Hospital, Oslo, Norway. sair@uus.no
Abdelnoor
Michael
M
D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006939:Hyperemesis Gravidarum / Q000453:epidemiology* / Q000209:etiology; D011247:Pregnancy; D012307:Risk Factors; D014481:United States / Q000453:epidemiology