Resistive Index: A Newly Identified Predictor of Outcome of Transurethral Prostatectomy in Patients With Benign Prostatic Hyperplasia

Abstract

To examine the usefulness of several preoperative parameters obtained through transrectal ultrasonography in predicting the outcome of transurethral resection of the prostate (TURP). A total of 572 men aged 51-85 years scheduled to undergo TURP for benign prostatic hyperplasia were prospectively enrolled, and 560 were ultimately evaluated. We preoperatively assessed International Prostate Symptom Score (IPSS), quality of life (QOL) score, maximum urinary flow rate (Q(max)), and postvoid residual urine volume (PVR), and measured total prostate volume (TPV), transition zone (TZ) index, and resistive index (RI) using transrectal ultrasonography. To compare the usefulness of the latter 3 indices, we calculated the area under the receiver operating characteristic (ROC) curve for each index and for IPSS. IPSS (total, postmicturition symptoms, storage symptoms, voiding symptoms), QOL score, Q(max), and PVR were significantly improved after TURP. Significant differences between the effective and noneffective groups were observed with regard to age, IPSS (total, postmicturition symptoms, storage symptoms, voiding symptoms), QOL score, TPV, TZ index, RI, Q(max), and PVR. The area under the ROC curve was 0.663 for IPSS, 0.691 for TPV, 0.719 for the TZ index, and 0.845 for the RI. The RI is a useful predictor of an effective outcome after TURP in patients with benign prostatic hyperplasia and may be useful for determining suitability for surgical intervention.