Prevalence and predictors of nocturnal polyuria in females with overactive bladder syndrome

Purpose To describe the prevalence and predictors of nocturnal polyuria (NP) in women with overactive bladder syndrome (OAB). Methods Between July 2009 and January 2018, women with OAB were enrolled. NP was defined when the nocturnal polyuria index (NPI) (nighttime voided volume over 24-h voided volume) was > 33% (NPI33) in women >= 65 years-old and > 20% (NPI20) in women < 65 years old. Repeated analysis was also performed for NP defined by the NPI33 definition at all ages. Results A total of 1071 women with OAB were analyzed. The overall prevalence of NP was 30% (319/1071), with the highest prevalence in women in the perimenopausal period (46-50 years old), while NP was diagnosed by age-dependent NPI. The overall prevalence of NP was 12% (128/1071), with an increasing trend with increasing age, while NP was diagnosed by the NPI33 definition only. Daytime frequency and nocturia episodes were both predictors for NP in both definitions. Receiver operating characteristic curve analysis revealed that more than 5 nocturia episodes noted in the 3-day bladder diary were an optimal cutoff value to predict nocturnal polyuria [(sensitivity = 85.6%, specificity = 61.0%; area = 0.80, 95% CI 0.77-0.82) and (sensitivity = 88.3%, specificity = 65.9%; area = 0.83, 95% CI 0.80-0.85), respectively, in the two definitions]. Conclusions NP is common in women with OAB, especially in women with more than 5 nocturia episodes in their 3-day bladder diaries, and adjuvant therapy for better treatment efficacy is needed.