Researchers have reported varying endpoints in assessing treatment options for overactive bladder (OAB). No published trials have compared controlled release once-daily oxybutynin-XL (OXY-XL) and twice daily tolterodine (TOL) using equivalent clinical endpoint for success, making it difficult to compare therapies. OBJECTIVE: Describe approach for comparing disparate OAB treatment outcome measures. METHODS: Clinical trial data supplemented with literature identified randomized controlled and open label safety trials involving OXY-XL or TOL. Patient outcomes were quantified using a correlational matrix to determine relationship between different endpoints. RESULTS: Three OXY-XL randomized clinical trials and one open label safety trial and three TOL trials were identified. All reported rate of reduction of urinary incontinence episodes (R-UI). The OXY-XL trials reported rate of complete continence (CC), defined as percent of patients with no UI episodes for 7 days. Mean CC rates for OXY-XL ranged from 41-50% (mean CC rate = 45.9% + 0.04). OXY-XL mean R-UI ranged from 79.5% to 89.5% (mean R-UI = 84.4% + 0.04). For TOL, R-UI rates ranged from 43.2% to 44.8%, (mean R-UI = 45.7% + 0.02). Computed CC rate for TOL was 24.6%. Correlation across all studies between CC and R-UI was high (r2 = 0.9975, p<0.0001) and consistent; R-UI:CC ratios within trials ranged from 1.8 to 1.9 (mean =1.85 + 0.08). Rate of reduction in UI episodes/week or day is approximately twice that of complete continence. CONCLUSIONS: Rate of complete continence may be derived from a surrogate endpoint by taking approximately one half the rate of reduction in R-UI episodes weekly, allowing direct efficacy comparisons on multiple measures.