Nocturia in patients with lower urinary tract symptoms: association with diurnal voiding patterns

OBJECTIVE To determine whether diurnal voiding patterns predict nocturia in patients with lower urinary tract symptoms (LUTS), as few studies have evaluated the association between diurnal and nocturnal voiding patterns. PATIENTS AND METHODS We prospectively analysed the frequency-volume charts (FVCs) of consecutive patients with LUTS. At the initial visit patients had a detailed clinical evaluation and subsequently were requested to complete a 72-h FVC. In all, 104 (41 men and 63 women, mean age 63 years, range 50-83) were included in the primary analyses. Associations between daytime variables and nocturia were described using maximum likelihood estimates of the relative risk and by 95% confidence intervals (CIs) based on logistic regression models. RESULTS When at least one night-time void was used to define nocturia the multivariate logistic model showed a negative association of mean daytime voided volume with nocturia (P = 0.001). The odds ratio for nocturia decreased with this variable to 0.98 (95% CI 0.96-0.99). When 'voiding at least twice per night' was used to define nocturia only the number of daytime voids was positively related to nocturia (odds ratio 1.22; 95% CI 1.01-1.48; P= 0.040). CONCLUSIONS Nocturia may be associated with diurnal voiding patterns; these results also suggest that the causes of nocturia of one or of two or more voids may differ. This highlights the role of bladder function in more severe forms of nocturia.