Overactive bladder: correlating symptoms with low cystometric capacity

: Overactive bladder (OAB) is a symptom complex that may be objectively assessed using urodynamic variables. The purpose of this study was to determine the correlation between OAB symptoms and low cystometric capacity (LCC).

: Between October and December 2005, 102 patients from the Urogynaecology Clinic at Mount Sinai Hospital participated in this prospectively planned, blinded, cross-sectional study. Participants underwent multichannel urodynamic testing and completed a symptom questionnaire focusing on urinary urgency, frequency, and urgency incontinence, in addition to recording fluid and caffeine intake. Answers were combined into symptom complexes and dichotomized into positive and negative responses. The diagnostic accuracy of OAB symptoms was assessed by calculating sensitivity, specificity, likelihood ratios, positive and negative predictive values, and Cohen's kappa, using urodynamic bladder capacity <350 mL as the reference.

: Fifty-seven percent (58) of participants met our urodynamic diagnosis of LCC with a bladder capacity <350 mL. Of the patients, 49% (50) had a questionnaire result that was classified as positive for overactive bladder. The questionnaire had a specificity of 61%, a likelihood ratio of 1.47, a sensitivity of 57%, and a positive predictive value of 66%. With a Cohen's κ = 0.2, there was poor reliability. Reanalysis using an alternative method of dichotomizing, a bladder capacity cut-off of <300 mL, and the addition of information regarding fluid intake, did not improve accuracy measures.

: Symptom history of OAB does not correlate with low cystometric capacity. We need further research to determine the accuracy of subjective and objective findings in patients with OAB, to provide the most accurate diagnosis in the least invasive manner.