Nocturia, nocturia indices and variables from frequency-volume charts are significantly different in Asian and Caucasian men with lower urinary tract symptoms: A prospective comparison study

OBJECTIVE: To describe and compare the patterns of nocturia in Asian and Caucasian men presenting with lower urinary tract symptoms (LUTS), and to identify associations or correlations between LUTS and variables from a frequency-volume chart (FVC), as nocturia is common among men with LUTS, and analysis of FVCs shows nocturnal polyuria and reduced nocturnal bladder capacity (NBC) as the predominant causes in Western patients, but there are few comparisons with other ethnic groups. PATIENTS AND METHODS: Consecutive men aged ≥ 40 years, presenting with LUTS and nocturia to an Asian and a Caucasian tertiary centre, were recruited prospectively. The men completed the International Prostate Symptom Score and a 3-day FVC. Men having had bladder outlet surgery and/or receiving anticholinergics were excluded. We computed the nocturia ratio, i.e. the nocturnal urine volume/ 24-h urine volume, nocturia index, predicted nocturnal voids and NBC index (NBCI), and analysed comparisons and correlations. RESULTS: In all, 93 Asian and 200 Caucasian men were recruited prospectively, with a similar age and overall severity of LUTS. The nocturia ratio was larger in the Caucasian men, whereas the NBCI was larger in the Asians (P < 0.001). The prevalence of nocturnal polyuria in men aged ≥60 years (nocturia ratio ≥0.3) was significantly higher in the Caucasian population. Conversely, the prevalence of reduced NBC appeared to be higher in the Asians (based on a NBCI of >2; P < 0.001). CONCLUSIONS: The patterns of nocturia and FVC variables differed significantly in age-matched Asian and Caucasian groups. There are also possible ethnic differences in the causes of nocturia, with nocturnal polyuria being more prevalent in Caucasians.