Study identifies unique subgroup of women with SUI

Key Points

Christchurch, New Zealand-Among women with stress incontinence and no signs of detrusor overactivity, there exists a significant subgroup with low voided volumes, high incidences of urgency and urge-related leaks, and relatively severe symptoms that can only be identified through careful evaluation, says a researcher from Birmingham Women's Hospital in the United Kingdom.

"The bladder remains an unreliable witness," said lead author Matthew Parsons, MRCOG. "Careful evaluation of all available symptoms and signs, with appropriate investigation, remains essential in the management of lower urinary tract dysfunction. These patients present a clinical picture that resembles overactive bladder."

Speaking at the International Continence Society annual meeting, Dr. Parsons reported results from an examination of 3-day, computer-analyzed bladder diaries and urodynamic assessments in 163 women. Of those, 57 patients (mean age, 57 years) with stress incontinence and no detrusor overactivity were pulled out for special analysis.

Leaks were categorized as "urge-predominant" if the number of urge-related leaks exceeded that of activity-related leaks or as "activity-predominant" if the reverse were true. Thirty-five diaries reported leaks with a predominance in one direction: 19 urge-predominant, 16 activity-predominant.

The 57 women were then classified by average voided volume as compared with a reference population of 161 asymptomatic women, after adjusting for relationships of average voided volume to age, and 24-hour volume. Interestingly, 73.7% of the women in the low-average-volume group who showed a predominance were found to have urge-predominant leaks, against only 31.3% of those who had normal voided volumes (p<.001).

"We were surprised at the level of urge-predominant leaks in women with proven urodynamic stress incontinence," said Dr. Parsons, consultant urogynecologist at Birmingham Women's Hospital.

The women in the low-voided-volume category also had a significantly higher rate of urgency symptoms versus the normal-volume cohort (71.4% vs. 46.4%, p<.04) and a higher median UDI score (52.8 vs. 22.2, p<.001).The low-volume patients also had a lower cystometric bladder capacity (450 vs. 500 mL), although that difference did not reach statistical significance.

Dr. Parsons offered possible explanations for the existence of the subgroup:

"It is hard to be exact as to the nature of the explanation from this study alone. Any or all of those hypotheses might be correct," said Dr. Parsons, who worked with colleagues from King's College Hospital, London; Loyola Medical Center, Chicago; Beaumont Hospital, Detroit; Duke University Medical Center, Durham, NC; and Life-Tech Inc. (Stafford, TX), which funded the research and provided the bladder diary software and equipment.