Abnormal uterine bleeding in premenopausal women and the role of body mass index

Abstract

We read with great interest the article by Wise et al1Wise M.R. Gill P. Lensen S. Thompson J.M. Farquhar C.M. Body mass index trumps age in decision for endometrial biopsy: cohort study of symptomatic premenopausal women.Am J Obstet Gynecol. 2016; 215: 598.e1-598.e8Abstract Full Text Full Text PDF Scopus (42) Google Scholar comparing the incidence of complex endometrial hyperplasia (EH) or cancer in premenopausal women with abnormal uterine bleeding and body mass index (BMI) ≥30 vs <30 kg/m2. They showed that a BMI ≥30 strongly associated with EH or cancer, and concluded that “BMI should be the first stratification in the decision to perform endometrial biopsy.”1Wise M.R. Gill P. Lensen S. Thompson J.M. Farquhar C.M. Body mass index trumps age in decision for endometrial biopsy: cohort study of symptomatic premenopausal women.Am J Obstet Gynecol. 2016; 215: 598.e1-598.e8Abstract Full Text Full Text PDF Scopus (42) Google Scholar Although the study is very interesting, from a diagnostic point of view there are some considerations to make about the authors’ conclusions. Given the low disease prevalence of the studied outcome (4.9%), the likelihood ratio (LR) can provide the best clinical implications. An optimal diagnostic test should have LR+ >10 and LR– <0.1.2Swets J.A. Measuring the accuracy of diagnostic systems.Science. 1988; 240: 1285-1293Crossref PubMed Scopus (7254) Google Scholar Based on the authors’ conclusions, if we use a BMI ≥30 as clinical triage for further investigation, we have a LR+ of 1.58 and a LR– of 0.47 for EH or cancer (based on Table 3). Now, a LR+ of 1.58 means that, when we have the presence of a BMI ≥30, it is unlikely that there is an EH or cancer (false-positives). A LR– of 0.47 means that, even if a BMI ≥30 is not present (ie, BMI <30), the probability of having an EH or cancer is still high (false-negatives). To better understand the contents, considering the disease prevalence as the pretest probability for EH or cancer (4.9%), the LR can be used to calculate the posttest odds from the pretest odds of disease: posttest odds = pretest odds × LR. The relation between odds and probability is: odds = P/(1 – P) and P = odds/(1 + odds). Using these equations, we could calculate the posttest probability of disease from the pretest probability of disease.3Gardner I.A. Greiner M. Receiver-operating characteristic curves and likelihood ratios: improvements over traditional methods for the evaluation and application of veterinary clinical pathology tests.Vet Clin Pathol. 2006; 35: 8-17Crossref PubMed Scopus (198) Google Scholar Limited to this scenario, we have a pretest probability for EH or cancer of 4.9% that would result in a posttest probability of 7.4% with a BMI ≥30. Conversely, we would have a posttest probability for EH or cancer of 2.3% with a BMI <30. In both cases the percentage gain is very poor. So, based on this analysis, it is very difficult to accept that “BMI should be the first stratification in the decision to perform endometrial biopsy.”1Wise M.R. Gill P. Lensen S. Thompson J.M. Farquhar C.M. Body mass index trumps age in decision for endometrial biopsy: cohort study of symptomatic premenopausal women.Am J Obstet Gynecol. 2016; 215: 598.e1-598.e8Abstract Full Text Full Text PDF Scopus (42) Google Scholar In a very recent systematic literature review, Pennant et al4Pennant M.E. Mehta R. Moody P. et al.Premenopausal abnormal uterine bleeding and risk of endometrial cancer.BJOG. 2017; 124: 404-411Crossref PubMed Scopus (56) Google Scholar showed that the risk of cancer or atypical EH in premenopausal women with abnormal uterine bleeding is very low (1.31%), and rarely requires biopsy. They stated that medical management should be the first choice for these women.4Pennant M.E. Mehta R. Moody P. et al.Premenopausal abnormal uterine bleeding and risk of endometrial cancer.BJOG. 2017; 124: 404-411Crossref PubMed Scopus (56) Google Scholar Body mass index trumps age in decision for endometrial biopsy: cohort study of symptomatic premenopausal womenAmerican Journal of Obstetrics & GynecologyVol. 215Issue 5PreviewClinical guidelines recommend that women with abnormal uterine bleeding with risk factors have an endometrial biopsy to exclude hyperplasia or cancer. Given the majority of endometrial cancer occurs in postmenopausal women, it has not been widely recognized that obesity is a significant risk factor for endometrial hyperplasia and cancer in young, symptomatic, premenopausal women. Full-Text PDF ReplyAmerican Journal of Obstetrics & GynecologyVol. 216Issue 5PreviewThank you for raising these comments in your letter to the editor.1 Full-Text PDF