In a 12-week , prospectively designed , superiority trial , fesoterodine 8 mg showed statistically significantly superior efficacy vs fesoterodine 4 mg and placebo , as measured by reductions in UUI episodes and other diary variables , diary-dry dry rate , and improvements in measures of symptom bother , HRQL , and other PROs ; clear evidence of dose-dependent efficacy is unique to fesoterodine among antimuscarinics and other oral agents for the treatment of OAB .