Performance of IOTA Simple Rules, Simple Rules Risk assessment, ADNEX model and O-RADS in discriminating between benign and malignant adnexal lesions in North American population

Objective To apply the International Ovarian Tumor Analysis (IOTA) Simple Rules (SR), IOTA Simple Rules Risk assessment (SRR), IOTA Assessment of Different NEoplasias in the adneXa (ADNEX) model, and the Ovarian-Adnexal Reporting and Data System (O-RADS) in the same cohort of patients and to compare their performance in the preoperative discrimination between benign and malignant adnexal lesions. Methods This is a single-center diagnostic accuracy study performed between March 2018 and February 2021, which includes 150 women with adnexal lesions. The lesions were classified prospectively using the ADNEX model; whereas, SR, SRR assessment, and O-RADS were applied retrospectively. Surgery with histology was performed within 6 months of the ultrasound exam. Sensitivity and specificity were determined for each testing modality. Results Of the 150 women, 110 (73.3%) had a benign ovarian tumor and 40 (26.7%) had a malignant tumor. The mean risk of malignancy generated by the ADNEX model without CA 125 was significantly higher in malignant lesions versus benign lesions, 63.3% vs 11.8%, respectively. The area under the receiver operating characteristic curve (AUC) of the ADNEX model for differentiating between benign and malignant adnexal masses at the time of ultrasound examination was 0.937. The mean risk of malignancy generated by SRR assessment was also significantly higher in malignant lesions than in benign lesions, 74.1% and vs 15.9%, respectively. The AUC of SRR assessment differentiating between benign and malignant adnexal masses at the time of ultrasound examination was 0.941. For purposes of comparison among ADNEX, SRR assessment, and O-RADS, the malignancy risk threshold was set at >10%. This cut-off differentiates O-RADS low-risk categories (3 or lower) from intermediate to high-risk categories (4 and 5). At a threshold malignancy risk of >10%, the sensitivity and specificity of the ADNEX model were 97.5% (95%CI, 85.3%-99.9%) and 63.6% (95%CI, 53.9%-72.4%), respectively; while, the sensitivity and specificity of the SRR model were 100% (95%CI, 89.1%-100%) and 51.8% (95%CI, 42.1%-61.4%), respectively. In the 113 cases for which the SR could be applied, sensitivity was 100% (95% CI, 81.5%-100%) and specificity 95.6% (95% CI, 88.5%-98.6%). If the designation of the 37 inconclusive cases is changed to "malignant," sensitivity remains at 100% but the specificity is reduced to 79.1% (95%CI, 70.1%-86.0%). The 150 cases fell into the following O-RADS categories: 17 lesions (11.3%) in category 2, 34 lesions (22.7%) in category 3, 66 (44.0%) lesions in category 4, and 33 (22.0%) in category 5. There were no histologically proven malignant lesions in either category 2 or 3. There were 14 malignant lesions in category 4 and 26 in category 5. The sensitivity and specificity of O-RADS using >10% threshold were 100% (95%CI, 89.1%-100.0%) and 46.4% (95%CI, 36.9%-56.1%), respectively. Conclusions When IOTA terms and techniques are used, the performance of IOTA models in a North American patient population is in line with published IOTA literature. The IOTA SR, SRR assessment, and ADNEX model and O-RADS have similar sensitivity in the preoperative discrimination of malignant and benign pelvic tumors; however, the IOTA models have higher specificity. This article is protected by copyright. All rights reserved.