Comparison of nocturia etiology in black and white male patients

Much of what is known about the etiology of nocturia (i.e., nocturnal polyuria [NP], small bladder capacity [SBC], etc.) at the population level stems from the Krimpen study, which enrolled aging males from a homogenous municipality in the Netherlands. Given the higher prevalence of benign prostatic hyperplasia and overactive bladder in black versus white males in population research, we aim to test the hypothesis that black males seeking treatment for lower urinary tract symptoms (LUTS) are more likely to have nocturia owing to SBC.

We retrospectively analyzed 24 hour frequency-volume charts (FVCs) completed by males seeking treatment for LUTS at a Veterans Affairs urology clinic from 2008-2016. Patients were included if they were ≥ 18 years, identified as either Caucasian or African American, and had a complete baseline FVC showing ≥ 1 nocturnal void. Patients were stratified by race and classified as having nocturia owing to SBC (defined by a maximum voided volume < 200 mL or a nocturnal bladder capacity index > 1.3); NP (defined by a nocturnal polyuria index > 0.33); 'mixed' (SBC + NP); or 'other' (neither SBC nor NP).

Between white and black patients, 28 (24%) versus 28 (26%) had NP, 32 (27%) versus 33 (30%) had SBC, and 35 (30%) versus 30 (28%) had mixed nocturia. Overall, there was no difference in distribution of underlying etiology by race (p = 0.51).

Our results demonstrate no difference in the etiology of nocturia between black and white males. Accordingly, race should not play a role in the evaluation of patients seeking treatment for nocturia.