External Validation of Models to Predict Unsuccessful Endometrial Ablation: a Retrospective Study

Study Objective: External validation of our previously presented and locally established prediction models to help counsel patients for failure of endometrial ablation (EA) or surgical re-intervention within 2 years after EA, called ‘Failure model’ and ‘Re-intervention model’ respectively. Design: Retrospective external validation study, minimal follow-up time of 2 years. Setting: Two non-academic teaching hospitals in the Netherlands. Patients: Pre-menopausal women (18+) who had undergone EA for abnormal uterine bleeding problems between January 2010 and November 2012. A total of 329 patients were eligible for analysis. Interventions: Interventions used for EA were Novasure (Hologic, Marlborough, Massachusetts, US) and ThermaChoice III (Ethicon, Sommerville, US). Measurements and Main Results: The Area Under the Receiver Operating characteristics Curve (AUROC) for the outcome parameter of failure within 2 years after EA was 0.59 (95% CI 0.53 – 0.65). Variables in this model were dysmenorrhea, age, parity ≥5 and preoperative menorrhagia. The Hosmer-Lemeshow test showed no significant difference between the observed and predicted outcome. (Chi-square: 4.62, P-value: .80) The AUROC for the outcome parameter surgical re-intervention within 2 years was 0.62 (95% CI 0.53 – 0.70) Variables in this model were dysmenorrhea, age, menstrual duration> 7 days, parity ≥5 and a previous caesarean section. The Hosmer-Lemeshow test showed no significant difference between the observed and predicted outcome (Chi-square 11.34, P-value .18). Conclusion: Both the failure model and the re-intervention model can be used to predict unsuccessful endometrial ablation in the general population within two years after the procedure. It can be used prior to surgery to facilitate tailor-made shared decision-making, and help counsel patients with regards to the potential outcome of their treatment with the use of a personally calculated percentage.