Diagnostic Accuracy of Risk of Malignancy Index (RMI) in Ovarian Masses

Aims: To determine the diagnostic accuracy of RMI in ovarian mass.

Study Design: Prospective, observational study.

Place and Duration of Study: Between November 2017-March, 2019 in the Department of Obstetrics and Gynaecology of Lady Hardinge Medical College and Smt. Sucheta Kriplani Hospital, New Delhi.

Methodology: We included a total of 50 women with ovarian masses coming to our OPD. Initial investigations were done and the RMI score was calculated based on Ultrasound score (U), Menopausal status (M), and CA-125 levels. The final diagnosis was made after the histopathological report and the RMI score at appropriate cut-off was evaluated by sensitivity, specificity, positive predictive (PPV), negative predictive (NPV), and diagnostic accuracy values concerning the ability to distinguish malignant from benign masses.

Results: In our study, benign ovarian masses were found in 64% and malignant in 36% based on histopathology. The majority of malignant mass was observed in the age group of 41-50yrs whereas benign in 21-30yrs. The mean RMI score was significantly higher in women with malignant ovarian masses compared to benign masses (1603.3±4093.1 vs. 18.95±21.62, p=0.032). A Standard cut-off of 200 and a lower cut-off of 100 calculated based on ROC curve was compared. Sensitivity, Specificity, and Diagnostic accuracy at 200 was 33.3%, 95.8%, and 69% respectively, whereas at 100 was 44.4%, 90.6% and 74%.

Conclusions: RMI is a simple multimodal scoring system with higher accuracy in predicting ovarian malignancy in preoperative evaluation. In our study, the diagnostic accuracy of RMI at cut-off 100 was better.