TRANSITION ZONE INDEX AS A METHOD OF ASSESSING BENIGN PROSTATIC HYPERPLASIA - CORRELATION WITH SYMPTOMS, URINE FLOW AND DETRUSOR PRESSURE

Purpose: Prostate volume has been poorly correlated to various paramet ers used to assess benign prostatic hyperplasia (BPH), including sympt oms, peak urine flow and detrusor pressure at peak urine flow. The pur pose of this study was 2-fold: 1) to determine if transrectal ultrasou nd measurement of the transition zone of-the prostate served as a bett er proxy for determining prostate size and correlated better with Amer ican Urological Association symptom score, peak urine flow and detruso r pressure, and 2) if the parameter transition zone index (the ratio b etween transition zone volume and prostate volume) was useful in evalu ating clinical prostatism. Materials and Methods: We prospectively eva luated 61 men with symptomatic BPH (age 64.6 +/- 9.7 years) according to symptoms, peak urine flow, pressure/flow analysis, transrectal ultr asound volume of the entire prostate and the transition zone, and calc ulation of the transition zone index. Results: Age correlated with sym ptoms (r = 0.31, p = 0.01) and peak urine flow correlated negatively w ith symptoms and age (p = 0.002). Age also correlated with prostate vo lume (r = 0.54 and p = 0.03) and transition zone (r = 0.31, p = 0.05). There was a weak correlation between prostate volume and symptoms, pe ak urine flow and detrusor pressure at peak urine flow; a stronger cor relation between transition zone and symptoms (r = 0.48, p = 0.03), an d peak urine flow (r = -0.34, p = 0.05), and a significant correlation (p = 0.001) between transition zone index and symptoms (r = 0.75), pe ak urine flow (r = -0.71) and detrusor pressure at peak urine flow (r = 0.43). A transition zone index of greater than 0.50 was a useful cut off point and highly significant (p = 0.002) for delineating patients with more severe abnormalities of symptoms, peak urine flow and detrus or pressure at peak urine flow. Conclusions: Transition zone index is a parameter that correlates significantly with evaluated parameters of BPH and may serve as a useful proxy for evaluating worsening obstruct ion. Studies are underway to determine if transition zone index can be used prospectively to predict and correlate response with therapies d esigned to ablate prostatic tissue medically or surgically.