Prevalence and predictors of overactive bladder in nonpregnant nulliparous women below 65 years of age

Abstract

Introduction and hypothesis: The aetiology of the overactive bladder (OAB) symptom complex is still poorly understood. In order to obtain further insight, the prevalence and predictors of the symptoms included in OAB, that is urgency, urgency incontinence (UUI), frequency and nocturia, were investigated in a sample of nonpregnant nulliparous women.

Methods: A national, postal and web-based survey of OAB symptoms was conducted in women aged 25-64 years (n = 9,197). Crude prevalence and prevalence adjusted according to body mass index (BMI) were calculated from a logistic regression model to evaluate the prevalence of OAB.

Results: The response rate was 52%. The prevalence of urgency, bothersome urgency, UUI, and nocturia, but not daytime frequency, increased consistently with advancing age and increasing BMI. Urgency was associated with BMI, age ≥45 years, nocturia, and daytime frequency of eight or more micturitions. Daytime urinary micturition frequency was not affected by age either in women with OAB or in women without OAB. Bothersome OAB affected almost half of the woman in the oldest age group and was strongly associated with nocturia of two or more micturitions and OAB with UUI.

Conclusions: There were contrasting changes in the prevalence of the different symptoms included in OAB. With increasing age and BMI, the prevalence of nocturia, urgency and UUI increased, while daytime frequency remained stable. These findings are of importance as the primary endpoint for the evaluation of drug therapies for OAB has often been daytime urinary frequency.

Keywords: Daytime frequency; Nocturia; Nulliparous women; Overactive bladder; Urgency.