Does frequency of nocturnal urination reflect the severity of sleep-disordered breathing?

Nocturia is an often-described symptom of sleep-disordered breathing (SDB). The aim of our study was to determine the frequency of nocturnal urination among patients with different severity of SDB and to find out whether frequency of nocturnal urination reflects the severity of disease. A retrospective chart review was conducted among 1075 subjects of suspected SDB. Nocturia was assessed using standard questionnaire evaluating a frequency of nocturnal urination. Subjects were divided into four groups of SDB based on the polysomnographic evaluation. In primary snoring group, 51% subjects did not complain nocturia, 28% subjects reported one time, 16% subjects reported two to three times and 5% subjects reported more than three times urination per night. Among patients with mild obstructive sleep apnea syndrome (OSAS), nocturnal urination was not reported by 36% and was reported one time by 34%, two to three times by 15%, more than 3 times by 15%. The corresponding frequencies among patients with moderate OSAS were 40, 31, 17 and 12%, and with severe OSAS were 23, 22, 23 and 32%, respectively. The severe OSA group was significantly different from other groups as regards the frequency of nocturnal urination (P < 0.001) while other OSA groups did not show any significance. Nocturnal urination of more than three times was significantly more reported by severe OSA patients ( P < 0.001) (positive predictive value = 0.71, negative predictive value = 0.62).