BERKELEY, CA (UroToday Inc.) - Female urinary incontinence has been traditionally described and divided by that which occurs in relation to physical exertion (stress urinary incontinence or SUI) and that which is preceded by the presence of the urge to void (urge incontinence). The overactive bladder (OAB) is a recent term, which describes a syndrome of symptoms defined by the International Continence Society as urgency, with or without urge incontinence, usually with frequency and nocturia. Stress incontinence usually occurs in relation to an insufficiency in the pelvic floor and urethral striated sphincter, while urge incontinence and OAB are believed to originate in the bladder or with neurological disorders.

The prevalence of overactive bladder, its relation with stress incontinence, and its association with other risk factors in middle-aged women was analyzed through the Women's Health In the Lund Area Study (WHILA). The WHILA is an observational study of over 6900 women between 50 and 59 years old that took place over a five-year period from 1995 to 2000 in Lund, Sweden. The results of this analysis were reported by P. M. Teleman and colleagues from Lund and published in the June, 2004 issue of BJOG: an International Journal of Obstetrics and Gynaecology.

From the WHILA study, in which 32% of women overall reported some aspect of urinary leakage, computer randomization selected 1500 women reporting troublesome urinary incontinence (INCONT-1) and 1500 without incontinence (CONT-1). Both groups completed the Bristol Female Lower Urinary Symptoms (BFLUTS) questionnaire in January 2001. Overactive bladder was further divided into two versions, OAB-1 (urgency alone) or OAB-2 which was urgency combined with frequency more than eight times per day and/or nocturia twice or more a night.

Analysis showed that the prevalence of OAB-1 was 46.9% in the INCONT-1 group and 16.7% in the CONT-1 group. OAB-2 was present in 21.6% of the INCONT-1 group versus 8.1% of the CONT-1 group. The great majority of urge incontinence occurred in conjunction with stress urinary incontinence, with only 3% reporting urge incontinence alone. Several risk factors were found to increase the risk of both types of urinary incontinence. A Body Mass Index (BMI) of > 30 was associated with a significant risk of OAB-1, OAB-2 and stress incontinence. In addition, a positive family history of diabetes was associated with a higher risk of OAB-2, and achievement of a BMI of > 25 since the age of 25 was a risk factor for stress urinary incontinence.

In summary, it appears that overactive bladder and stress incontinence are intimately associated with each other. Both OAB and stress incontinence are associated with abnormal metabolic factors such as body mass index.

BJOG. 2004; 111(6):600-4