OP06.06: LR2 versus simple rules: a meta‐analysis comparing the performance of ACOG‐recommended tools for differentiating adnexal masses

To compare the sensitivities and specificities of two ultrasound models, IOTA logistic regression 2 (LR2) and simple rules (SR), in differentiating between benign and malignant pathology in known adnexal masses. This meta-analysis used the MEDLINE database to find primary articles which compared various models of evaluating adnexal masses for malignancy. To account for advances in ultrasound technology and the date of the most recent recommendation by the American College of Obstetricians and Gynecologists (ACOG) for evaluating adnexal masses, the search was limited to articles published between 2016 and 2024. 204 articles were investigated by one reviewer for adnexal masses which were assessed using LR2 or SR and confirmed by postoperative pathology. Across the 20 articles which met inclusion criteria, the results of assessments for 6,413 adnexal masses were extracted and compared using ultrasound classification as test outcomes and postoperative pathology as true outcomes. The cutoff value for malignancy using LR2 was 0.10 for all masses. Masses that did not fit into either category (benign or malignant) using SR were classified as malignant. LR2 exhibited a sensitivity of 84% and a specificity of 84.5%. Contrastingly, SR demonstrated a sensitivity of 86.3% and a specificity of 90.5%. Statistical analysis revealed significant differences indicating SR had a higher sensitivity (p = 0.0051) and superior specificity (p < 0.0001) over LR2. These findings highlight the potential advantages of utilising SR over LR2 in the ultrasound-based evaluation of adnexal masses, particularly in achieving higher sensitivity and specificity. ACOG recommends using either LR2 or SR in patients with known adnexal mass to assess for malignancy, but our review suggests the latter may have superior performance. We propose that more research should be conducted to support our hypothesis that SR should be preferred over LR2 for adnexal mass sonography.