External Validation of the PRI-MUS Scoring System: A Secondary Analysis of the OPTIMUM Randomized Controlled Trial

PURPOSE: Micro-ultrasonography (microUS)-guided biopsy has emerged as an alternative to MRI fusion-guided biopsy for the diagnosis of prostate cancer. This study aimed to externally validate the PRI-MUS (Prostate Risk Identification using Micro-Ultrasound) scoring system for predicting clinically significant prostate cancer (csPCa) using data from the OPTIMUM trial. MATERIALS AND METHODS: A secondary analysis of the OPTIMUM trial was conducted to evaluate the diagnostic performance of the PRI-MUS scoring system. The analysis included patients who underwent microUS-guided prostate biopsy, with each core assigned a PRI-MUS score. The diagnostic performance of the PRI-MUS scoring system for identifying csPCa was assessed at per-core and per-lesion levels. RESULTS: Three hundred forty-seven patients receiving microUS-guided biopsy were included. At the per-core level, 4590 biopsy cores were analyzed and assigned a PRI-MUS score. When comparing PRI-MUS 1 to 2 vs 3 to 5, the sensitivity, specificity, positive predictive value, and negative predictive value (NPV) for detecting csPCa were 72%, 74%, 37%, and 93%, respectively. The AUC was 0.78 (95% CI: 0.76 to 0.8). At the per-lesion level, 322 lesions were analyzed. When comparing PRI-MUS 1 to 2 vs 3 to 5, the corresponding sensitivity, specificity, positive predictive value, and NPV were 92%, 34%, 55%, and 83%, respectively. The AUC was 0.78 (95% CI: 0.73-0.82). Nineteen high-risk anterior lesions were biopsied, with csPCa detected in 11 (57.8%). CONCLUSIONS: The PRI-MUS scoring system demonstrated high sensitivity and NPV for diagnosing csPCa at both the per-core and per-lesion levels, supporting its validity as a risk-stratification tool for microUS-guided biopsy.