Is the ratio of transition zone to total prostate volume higher in African-American men than in their Caucasian or Hispanic counterparts?

Objective To determine if the transition zone index (TZI, the ratio between transition zone volume, TZV, and total prostate volume, as estimated by tr ansrectal ultrasonography, TRUS) differs among African-American (AA), Hispa nic and Caucasian men. Patients and methods The study group consisted of 104 age-matched men (36 A A, 34 Hispanic and 34 Caucasian) with lower urinary tract symptoms secondar y to benign prostatic hyperplasia (BPH). A control group of 55 age-matched men, equally distributed among the three ethnic groups, but with no BPH (ba sed on a digital rectal examination) were also evaluated, All men completed the International Prostate Symptom Score (IPSS) and a measurement of peak urinary now rate (Q(max)), prostate volume and TZV (by TRUS) and the TZI ca lculated, Results In the control group, the mean prostate volume was 20.9, 18.2 and 1 9.8 mt, the TZV 6.9, 4.9, and 5.4 mt and the TZI 0.33, 0.27 and 0.25 for AA , Hispanic and Caucasian men, respectively. The TZI was significantly highe r in AA than in either Hispanic or Caucasian men (P<0.03). Although there w ere no differences in prostate volume among the three ethnic groups with BP H, the mean (SD) TZV and TZI were significantly higher in AA men than in ei ther their Hispanic or Caucasian counterparts, at 15.8 (7.6) mt and 0.43, 1 2.7 (8.1) mt and 0.37, and 13.8 (6.7) mL and 0.37, respectively, For all gr oups, age correlated with the IPSS (r = 0.22, P < 0.04); the mean (SD) IPSS was 14.3 (5.7), 10.2 (2.9) and 10.6 (4.9) for AA. Hispanic and Caucasian m en, respectively, There was no correlation between the IPSS and either pros tate volume or TZV, but there was a strong correlation with the TZI (r = 0. 25, P < 0.01), regardless of race. Conclusions These results suggest that AA men have a greater TZV and a high er TZI than their Caucasian or Hispanic counterparts, regardless of the pre sence of lower urinary tract symptoms, Studies are underway to determine if these differences are clinically significant and correlate with either sub jective and/or objective parameters of BPH.