Increased prevalence of interstitial cystitis in women with detrusor overactivity refractory to anticholinergic therapy.

OBJECTIVES

To estimate the prevalence of interstitial cystitis in women with detrusor overactivity refractory to anticholinergic medication using the potassium sensitivity test (PST).

METHODS

Women with complaints of urinary frequency, urgency, and/or urge incontinence of 3 months' duration or longer were referred to the urogynecology clinic. Between October 2003 and June 2004, 47 consecutive women were diagnosed with phasic, idiopathic detrusor overactivity after evaluation by history, physical examination, urinalysis, urine culture, urodynamic testing, and cystoscopy. Refractory detrusor overactivity was defined as a 50% or less improvement in urinary urgency, frequency, and/or urge incontinence episodes while taking anticholinergic medications. All women were offered the PST.

RESULTS

All 47 women were included in the study; 18 (38.3%) had only detrusor overactivity incontinence and 29 (61.7%) also had concomitant urodynamic stress incontinence. Additionally, 19 women (40.4%) had pelvic pain. Of the 47 women, 31 agreed to undergo the PST. Of the 31 women, 25 had positive and 6 had negative PST result. Of the 31 women, 25 did not respond to therapy with one or more anticholinergic medications, and 24 (96%) of these 25 had had a positive PST. The remaining 6 women responded to treatment with oxybutynin, and only 1 (16.7%) had had a positive PST (P = 0.0002). The odds ratio of a positive PST for women in whom anticholinergic therapy failed compared with women in whom it did not was 120.0 (95% confidence interval 6.4 to 2257.5; P = 0.0002).

CONCLUSIONS

These preliminary findings suggest that there is a high prevalence of interstitial cystitis in women with detrusor overactivity that does not respond to anticholinergic medication.