Chen et al. Respond to “Studying the Epidemiology of Uterine Leiomyomata” by Schwartz

We thank Dr. Schwartz for reviewing the methodological issues underlying the epidemiologic study of uterine leiomyomas, or fibroids (1). We concur with him about the paucity of available research despite the prevalent nature of this gynecologic condition. We would like to respond to the concerns raised by Dr. Schwartz regarding our case ascertainment and choice of analytical strategy, both of which impacted on our interpretations. Dr. Schwartz discussed two factors that may have resulted in underascertainment of cases in our study: use of laparoscopy and the lack of a protocol for laparoscopic detection of fibroids. As we noted in the description of our methodology (2), this study was originally designed to assess the safety and efficacy of tubal ligation. Hence, women were not undergoing laparoscopic screening for asymptomatic disease per se. We agree that there may have been misclassification of controls due to the inability of laparoscopy to detect fibroids within the myometrium or endometrium. Fibroids located at these sites may be associated with heavier bleeding, thereby increasing the likelihood of clinical recognition and diagnosis. We are unaware of population-based data delineating fibroids with respect to size, location, or symptomology which would enable us to better characterize the extent of underascertainment of cases in our sample and the implications for study findings. Concerning the absence of a protocol for the detection of fibroids in our study, it should be noted that surgeons were instructed to systematically record any and all gynecologic pathology visualized at the time of sterilization.