Dear Editor:
Upon reading the recently published article entitled "Adverse pregnancy outcomes with assisted reproductive technology in non-obese women with polycystic ovary syndrome: a case control study" [1], we were compelled to point out that the study design does not conform to the principles of a case-control study. The authors state that the aim of the study was to compare the prevalence of adverse pregnancy outcomes between non-obese women with polycystic ovary syndrome compared to a control group. However, the study participants were selected on the basis of the specific exposure groups; for case control studies participants are selected on the basis of an outcome of interest. Thus, the authors have conducted a cohort study.
Footnotes
No potential conflict of interest relevant to this article was reported.
References
- 1.Han AR, Kim HO, Cha SW, Park CW, Kim JY, Yang KM, et al. Adverse pregnancy outcomes with assisted reproductive technology in non-obese women with polycystic ovary syndrome: a case-control study. Clin Exp Reprod Med. 2011;38:103–108. doi: 10.5653/cerm.2011.38.2.103. [DOI] [PMC free article] [PubMed] [Google Scholar]