To investigate whether the resistive index (RI) in symptomatic benign prostatic hyperplasia (BPH) could be used as a surrogate index of the severity of lower urinary tract symptoms (LUTS) due to BPH, and whether arteriosclerosis-related factors were associated with the RI in LUTS due to BPH.

From January 2005 to April 2008, a total of 625 men with LUTS due to BPH were prospectively enrolled. Patients with heart failure, liver cirrhosis, prostatic cancer, neurogenic bladder, acute prostatitis, acute urinary retention, urethral stenosis, history of transurethral resection or any drug treatment for BPH, or currently under drug treatment for type 2 diabetes mellitus or dyslipidemia were excluded. Variables analyzed included estimated smoking status, blood pressure, body mass index (BMI), serum fasting glucose (FBS), lipid profile (low-density lipoprotein-cholesterol, high density lipoprotein-cholesterol and triglyceride), serum prostate-specific antigen, International Prostatic Symptom Score (IPSS), quality of life score, maximum urinary flow rate (Q_max.), and postvoid residual urine volume (PVR). We also measured total prostate volume, transition zone (TZ) index, and RI using transrectal ultrasonography. Correlations among parameters were statistically examined.

RI was significantly correlated with IPSS, Q_max., and PVR, but not with blood pressure, BMI, or FBS. On multiple regression analysis, RI was a significant independent variable of IPSS, TZ index, and PVR.

These findings suggest that RI might represent a surrogate index of the severity of LUTS due to BPH, and that RI might have no clinically significant relationship with arteriosclerosis-related factors.