Persistence and adherence with mirabegron vs antimuscarinics in overactive bladder: Retrospective analysis of a UK General Practice prescription database.

Abstract

Persistence with antimuscarinic (AM) drugs prescribed for overactive bladder (OAB) is poor. This study aimed to compare persistence and adherence with the beta-3-adrenoceptor agonist mirabegron (MIR) vs AMs over 12months. This retrospective cohort analysis included patients aged ≥18years who were prescribed MIR, or any AM. A 12-month look-back was used to assess inclusion eligibility. The primary end-point was persistence, defined as time to first discontinuation of index drug, during 1year follow-up. The secondary end-point was adherence, estimated by medication possession ratio (MPR). Inclusion criteria were met by 6189 patients. Those prescribed AMs were mostly treatment-naïve (range 72.9%-95.3%) vs 54.4% of MIR patients. There was greater persistence with MIR vs AM. The median number of days on therapy with MIR was 101, vs 27-56 for AMs. Patients receiving AMs were significantly more likely to discontinue than those receiving MIR (hazard ratio [HR] range 1.24-2.05, P<.01 for each AM vs MIR. In treatment-naïve patients, HRs ranged from 1.25 (solifenacin, P=.012) to 2.07 (oxybutynin IR, P<.001). In treatment-experienced patients, they ranged from 1.10 (fesoterodine, P=NS) to 2.12 (oxybutynin IR, P<.001). Adherence was greater with MIR (mean MPR 48.4%) than with AMs (range 27.6%-40.4%, P<.001). Treatment-experienced patients were significantly less likely to discontinue treatment (HR 0.87, P=.006). MIR was associated with a significantly longer time to discontinuation, greater persistence and better adherence than AMs. However, there was a steep decline in persistence with all drugs after 1month. This is unlikely to be wholly explained by anticholinergic adverse events, as it was also seen with MIR. The lower proportion of MIR patients who were treatment-naive reflects current prescribing guidelines whereby MIR is prescribed after an initial generic AM trial. The study was limited by the small number of MIR patients. Study identifier: ISN 178-MA-3059.