Developing a predictive model for minimal or mild endometriosis as a clinical screening tool in infertile women: uterosacral tenderness as a key predictor

Study Objective To develop a non-invasive predictive model based on patients with infertility for identifying minimal or mild endometriosis. Design A retrospective cohort study. Setting This study was conducted at a tertiary referral center. Patients A total of consecutive 1365 patients with infertility who underwent laparoscopy between January 2013 and August 2020 were divided into a training set (n=910) for developing the predictive model and a validation set (n=455) to confirm the model's prediction efficiency. The patients were randomly assigned in a 2:1 ratio. Interventions Sensitivities, specificities, area under the curve (AUCs), the Hosmer-Lemeshow goodness of fit test, Net Reclassification Improvements (NRIs) and Integrated Discrimination Improvements (IDIs) were evaluated in the training set to select the optimum model. In the validation set, the model's discriminations, calibrations and clinical use were tested for validation. Measurements and Main Results In the training set, there were 587 patients with minimal or mild endometriosis and 323 patients without endometriosis. The combination of clinical parameters in the model was evaluated for both statistical and clinical significance. The best-performing model ultimately included body mass index (BMI), dysmenorrhea, dyspareunia, uterosacral tenderness and serum CA-125. The nomogram based on this model demonstrated sensitivities of 87.7% and 93.3%, specificities of 68.6% and 66.4%, and AUCs of 0.84 (95% confidence interval [CI] 0.81-0.87) and 0.85 (95% CI 0.80-0.89) for the training and validation sets, respectively. Calibration curves and decision curve analysis (DCAs) also indicated that the model had good calibration and clinical value. Uterosacral tenderness emerged as the most valuable predictor. Conclusion This study successfully developed a predictive model with high accuracy in identifying infertile women with minimal or mild endometriosis based on clinical characteristics, signs and cost-effective blood tests. This model would assist clinicians in screening infertile women for minimal or mild endometriosis, thereby facilitating early diagnosis and treatment.