Obesity and stress urinary incontinence: significance of indices of relative weight.

We analyzed the significance of weight and various indices of relative weight in the assessment of genuine stress incontinence (GSI) in 193 female patients. Body mass index [BMI = weight/(height2)] and the other indices of relative weight [weight/height - weight/(height3)] were not markedly different between patients with GSI and a control group of 43 females without demonstrable incontinence. A markedly increased BMI was found to be correlated with a positive clinical stress test. In addition BMI was significantly higher in patients with a higher maximum urethral pressure. We conclude that although obese women tend to have higher maximum urethral pressures, this advantage disappears in regard to the maximum urethral closure pressure, resulting in a higher prevalence of positive clinical stress test.