Assessing Preference-Based Outcome Measures for Overactive Bladder: An Evaluation of Patient-Reported Outcome Data from the BESIDE Clinical Trial

Objectives The aim of this study was to compare outcomes using two preference-based measures of health status (EQ-5D-5L and OAB-5D) in patients with overactive bladder (OAB) treated with solifenacin plus mirabegron or solifenacin monotherapy in the BESIDE trial. Methods Patients with OAB who remained incontinent after 4 weeks' treatment with solifenacin 5 mg were randomized 1:1:1 to combination treatment (solifenacin 5 mg plus mirabegron [25 mg for the first 4 weeks/50 mg for the last 8 weeks]), solifenacin 5 mg, or solifenacin 10 mg. EQ-5D-5L and OAB-q were administered at baseline, weeks 4, 8, 12, and end of treatment (EoT). OAB-5D scores were derived from OAB-q results. Responder analysis was carried out using several definitions of minimally important difference. Results A total of 2054 patients received one or more doses of study treatment (combination, n = 694; solifenacin 5 mg, n = 684; solifenacin 10 mg, n = 676). EQ-5D-5L Index mean score changes (from baseline to EoT) were greater with combination (0.059) than with solifenacin 5 mg (0.040) and 10 mg (0.044) monotherapy, but the differences were not statistically significant. A significantly greater improvement was observed for combination on OAB-5D (0.107 vs 0.085 for 5 mg, and 0.087 for 10 mg; p <= 0.01). The dimensions most improved overall were anxiety/depression, pain/discomfort, and usual activities on EQ-5D-5L, and urge, urine loss, and coping on OAB-5D. The proportion of responders was significantly greater with combination compared with monotherapy using OAB-5D only. Conclusions Improvements were observed in all study arms on both the EQ-5D-5L and OAB-5D, although only the OAB-5D showed a statistically significant benefit for combination versus solifenacin monotherapy. Combining generic and condition-specific preference-based health status measures allowed for assessment of dimensions that were particularly relevant to this patient population, while permitting comparison with outcomes from other studies, treatments, and populations via EQ-5D.