We were pleased to see this report focusing on the frequency of lower abdominal and pelvic pain in women with advanced pelvic organ prolapse. We would like to congratulate the authors for including a control group of women with normal vaginal support, the use of valid and reliable questionnaires, and the demonstration of differences seen in all pain-related questions within these questionnaires.

We agree that including a control group without prolapse may help us put the results in the right perspective. However, this study is mislabeled as a case-control study. It is surprising that it was overlooked by the editors, even when this was stated in the title of the article. It actually is a cross-sectional study because it is measuring the frequency of the outcome of interest, pain, for a given population with certain exposure, advanced pelvic organ prolapse.

A case-control study, on the other hand, starts from the outcome and looks back to see whether the exposure to any factor is more common in the cases than it is in the controls. Surprisingly, mislabeling the study design is not rare. Just recently, Grimes reviewed all highly regarded journals in our field. He reported that, among 124 reports that were described as case-control in the title, 30% were mislabeled. Most of these studies were in fact retrospective cohort studies.

On a final note, the baseline characteristics of the groups are quite different. In particular, certain comorbidities, prior hysterectomy, or prolapse surgery may well be contributing to lower abdominal or pelvic pain. Although the authors utilized a multiple logistic regression method to control for these variables, it possibly could have been more appropriate to take these differences into account when constructing the study and control groups.