Overactive bladder: prevalence, risk factors and relation to stress incontinence in middle-aged women

Abstract

Objective: To investigate the prevalence of and factors associated with overactive bladder in middle-aged women.

Design: Cross sectional population-based study.

Setting: Southern Sweden and the Women's Health in the Lund Area study (WHILA 1995-2000) where 6917 (64% of the invited) women, 50-59 years old in 1995, participated.

Population: From the WHILA study, 1500 women reporting troublesome urinary incontinence (INCONT-1) and 1500 without incontinence (CONT-1) were selected by computerised randomisation and received the Bristol Female Lower Urinary Tract Symptoms (BFLUTS) questionnaire in January 2001.

Methods: Overactive bladder was defined in two versions using the ICS definition of 2002 as either urgency alone (OAB-1) or urgency combined with frequency more than eight times per day and/or nocturia twice or more per night (OAB-2). Risk factors were analysed by multiple logistic regression analyses.

Main outcome measures: Prevalence figures and odds ratios with corresponding 95% confidence intervals.

Results: The prevalence of OAB-1 was 46.9% in the INCONT-1 and 16.7% in the CONT-1 group, and that of OAB-2 was 21.6% and 8.1%, respectively. Most urgency occurred in combination with stress incontinence (i.e. as mixed incontinence). The overlap between stress and urge symptoms increased with the frequency of stress incontinence episodes (P < 0.001). Metabolic risk factors were body mass index (BMI) >/= 30 for OAB-1, OAB-2 and stress incontinence, positive metabolic screening for OAB-1, family history of diabetes for OAB-2 and elevation of BMI >/= 25% since the age of 25 for stress incontinence. Stress incontinence was associated with the current use of hormonal replacement therapy.

Conclusions: Overactive bladder and stress incontinence are intimately associated with each other. Both OAB and stress incontinence are associated with abnormal metabolic factors, mainly increased BMI.