Prevalence, impact on the quality of life and pathophysiological determinants of nocturia in urinary incontinent women

The objective of this study was to estimate the prevalence of nocturia in incontinent women in a urogynaecologic practice and its association with the quality of life and to estimate the prevalences of the pathophysiological categories among nocturics. From 1 January 2002, all patients with complaints of urinary incontinence were analysed according to a specific protocol: multichannel urodynamic testing, a 1-h International Incontinence Society (ICS) pad test and a 3-day frequency-volume (FV) chart. From 1 June 2002, subjects had to fill in a standardised quality of life questionnaire as well. Nocturia was defined as two or more micturitions per night calculated from the FV chart. Evaluable FV charts were received from111 patients, and 72 patients completed the questionnaires correctly. The overall prevalence of nocturia was 48.6% (confidence interval: 43.9–53.3%). Nocturia had a negative impact on several aspects of the quality of life. The maximum voided volume was significantly (p=0.005) less in nocturics. The 24-h frequency was higher in nocturics (p=0.001). Nocturics lost more urine during the pad test (p=0.039). The multivariate logistic regression analysis showed that the greater the proportion of 24-h urine excreted at night, the greater the odds of having nocturia and that the lesser the maximum voided volume, the greater the odds of having nocturia. The majority (92.7%) of the nocturics can be classified into one of the responsible pathophysiologic categories: nocturnal polyuria in 51.2%, a low functional bladder capacity in 14.6%, a combination of both in 9.8%, polyuria in 4.9% and a combination of polyuria and nocturnal polyuria in 12.2% of the cases. Nocturia is a frequent symptom among urinary incontinent patients, with a negative impact on several aspects of the quality of life. With a FV chart, nocturics can be classified into one of the responsible pathophysiologic categories in the majority (92.7%) of the cases.