Is the higher prevalence of benign prostatic hyperplasia related to lower urinary tract symptoms in Korean men due to a high transition zone index?

OBJECTIVE

Asian men generally have smaller prostate gland sizes than their Western counterparts. Nonetheless, the prevalence of lower urinary tract symptoms (LUTS) is similar between native Asian men and men in the Western hemisphere. The purpose of this study was to determine if the enlargement of the transition zone volume (TZV) relative to the overall prostate volume (PV) might account for the prevalence of LUTS among Korean men despite having "smaller" prostates.

METHODS

Three hundred and seventy consecutive age-matched men (94 Caucasian, 94 Hispanic, 93 African-American, and 89 Korean) with LUTS were evaluated utilizing the International Prostate Symptom Score (IPSS), peak flow rate (Q(max)), serum PSA and transrectal ultrasound (TRUS). The ratio of TZV to total PV was used to determine the transition zone index (TZI).

RESULTS

Mean baseline IPSS and Q(max) were significantly different (p<0.001 and p<0.03) for Korean men (19.9+/-7.6 and 11.3+/-4.2) in comparison to African-American (14.6+/-3.7, 12.6+/-4.1), Caucasian (13.4+/-4.3, 12.5+/-3.8), and Hispanic (13.9+/-3.1, 11.9+/-4.5) men. Regardless of race, TZI correlated with IPSS (r=0.31, p<0.01) and Q(max) (r=0.26, p<0.04). Mean TZI was significantly (p<0.001) higher in Korean and African-American men (0.45+/-0.08 and 0.44+/-0.05, respectively) than Caucasian and Hispanic men (0.39+/-0.03 and 0.38+/-0.02, respectively).

CONCLUSIONS

Among age-matched, ethnically diverse men with moderate to severe LUTS, Korean men demonstrated more clinical symptoms and a higher ratio of transition zone enlargement relative to total prostate in comparison to Caucasian, Hispanic, and African-American men. The clinical significance of these findings remains to be determined.