Prediction of nocturia severity in men: Nocturnal urine overproduction vs race or metabolic risk factors

IMPORTANCE: Nocturia is one of the most common and bothersome of lower urinary tract symptoms. OBJECTIVE: To examine the effect of race and metabolic risk factors on nocturia severity in men as measured by the number of nightly voids. DESIGN, SETTING, AND PARTICIPANTS: A retrospective review from 2011 to 2013 was performed at a Veterans Affairs-based urology clinic in Brooklyn, New York, among 104 adult men 18 years or older who completeda 24-hour frequencyand volume chart. Metabolic risk factors included race and a history of diabetes mellitus, hypertension, and obstructive sleep apnea. The 24-hour frequency and volume chart data included the nocturia index (nocturnal urine volume divided by maximal voided volume), the nocturnal polyuria index (nocturnal urine volume divided by 24-hour volume), and nocturnal urine production (nocturnal urine volume per hours slept). A nocturia index of less than 2 vs 2 or higher, a nocturnal polyuria index of less than 33% vs 33% or higher, and nocturnal urine production of less than 90 vs 90 mL/h or higher were chosen as clinically relevant cutoff points for nocturia severity. Nocturia severity was compared by race, the aforementioned variables, and the presence or absence of diabetes mellitus, hypertension, and obstructive sleep apnea. MAINOUTCOMES AND MEASURES: The number of nightly voids. RESULTS: One hundred four adult men (mean age, 64 years; age range, 24-92 years) completeda 24-hour frequencyand volume chart (mean number ofnightly voids, 2.93; range, 0-15). The number of nightly voids was not statistically different for white vs black race (3.00 vs 2.93, P = .86) or for the presence vs the absence of diabetes mellitus (3.00 vs 2.88, P = .85), hypertension (2.94 vs 2.80, P = .75), and obstructive sleep apnea (3.29 vs 2.83, P = .50). However, nocturia severity was significantly different based on a nocturia index of less than 2 vs 2 or higher (1.39 vs 3.60), a nocturnal polyuria index of less than 33% vs 33% or higher (1.83 vs 3.65), and nocturnal urine production of less than 90 vs 90 mL/h or higher (2.27 vs 3.77) (P < .001 for all). CONCLUSIONS AND RELEVANCE: Neither race nor metabolic risk factors affect nocturia severity. In contrast, variables that denote nocturnal urine overproduction sharply discriminate the risk of nocturia severity and suggest that variable data may provide useful clinical correlation.