The overlap of interstitial cystitis/painful bladder syndrome and overactive bladder.

Objective: We evaluated the prevalence of positive potassium sensitivity and cystoscopy with hydrodistention findings in patients with overactive bladder.

Method: This was a prospective cohort study of 98 patients who presented with overactive bladder symptoms. The diagnosis of overactive bladder is established by the presence of irritable voiding symptoms. All patients completed a PUF questionnaire and underwent potassium sensitivity testing. Eighty patients underwent urodynamic testing, and 42 patients underwent cystoscopic hydrodistention while under general anesthesia.

Results: The Potassium Sensitivity Test was positive in 59 (60.2%) of the 98 patients, 37 (56%) of wet overactive bladder patients, and 22 (68.8%) of dry overactive bladder patients. Their mean PUF score was 7. Thirty-three (78.5%) of the patients who underwent cystoscopic hydrodistention had glomerulations consistent with NIH criteria for interstitial cystitis, and 26 of these patients tested positive for potassium sensitivity. Fifty-one (63.8%) of the patients who underwent urodynamics tested positive for potassium sensitivity.

Conclusion: Many patients with symptoms of overactive bladder with little or no pain have cystoscopic evidence of interstitial cystitis and a positive Potassium Sensitivity Test. Therapies directed toward the uroepithelial dysfunction and neural upregulation associated with interstitial cystitis/painful bladder syndrome may be an important adjunct for patients who have failed or have had a partial response to anticholinergic therapy and behavior modification.