Performance of the Risk of Malignancy Index for Discriminating Malignant Tumors in Women With Adnexal Masses

Abstract

OBJECTIVES: We examined the performance of 4 risk of malignancy index (RMI) variants in a medium-resource gynecologic cancer center. METHODS: A total of 158 women referred for adnexal masses were evaluated before surgery by the 4 RMI variants. Physicians with varied experience in ultrasound assessment of adnexal masses performed ultrasound examinations. We compared the performance of the 4 RMI variants using receiver operating characteristic curve analyses followed by calculation of sensitivity, specificity, and positive and negative likelihood ratios using the pathologic diagnosis of the masses as the reference standard. RESULTS: Among the 158 women with adnexal masses included in this study, 51 (32%) had malignant tumors; 26 (51%) of them were stage I. All RMI variants performed similarly (accuracy range, 74%-83%), regardless of menopausal status. Considering all women included, the positive likelihood ratios of the 4 RMI variants ranged from 3.52 to 4.41. In subset analyses, all RMI variants had decreased sensitivity for stage I malignant tumors and for those of nonepithelial histologic types. CONCLUSIONS: The 4 RMI variants performed acceptably in a medium-resource setting where ultrasound examiners were physicians with varied experience. This finding indicates a good tradeoff between performance and feasibility, since ultrasound RMI protocols are of low complexity.