Mirabegron and antimuscarinic use in frail overactive bladder patients in the United States Medicare population

Abstract

Introduction: Overactive bladder (OAB) and frailty are independently associated with patient burden. However, economic burden and treatment-taking behavior have not been well characterized among frail patients with OAB, which, given the varying safety and tolerability profiles of available treatments, is crucial.

Objectives: To assess costs, health care resource utilization, treatment-taking behavior (persistence and adherence) to OAB medication in older, frail OAB patients.

Methods: This was a retrospective cohort study using international business machines MarketScan Medicare Supplemental claims data. Eligible frail patients (per Claims-based Frailty Index score) initiating mirabegron were 1:2 propensity score matched (based on age, sex, and other characteristics) with those initiating antimuscarinics and were followed up to 1 year. All-cause, per-person, per-month costs, health care encounters, persistence (median days to discontinuation assessed using Kaplan-Meier methods) and adherence (≥80% of proportion of days covered at Day 365) were compared.

Results: From 2527 patients with incident mirabegron (21%) or antimuscarinic (79%) dispensations, 516 incident mirabegron users (median age: 82 years, 64% female) were matched to 1032 incident antimuscarinic users (median age: 81 years, 62% female). Median cost was higher in mirabegron group ($1581 vs. $1197 per month); this was primarily driven by medication cost. There was no difference in medical encounters. Adherence (39.1% vs. 33.8%) and persistence (103 vs. 90 days) were higher in mirabegron users.

Conclusions: Among frail older adults with OAB, mirabegron use was associated with higher costs and potential improvements in treatment-taking behaviors, particularly with respect to treatment adherence, versus those initiating antimuscarinics.

Keywords: adherence; costs; frail; health care resource utilization; persistence.

Figure 1

Patient Attrition. [1] Index date was defined as the first claim date of MIRA or AMs during the ascertainment period (January 10, 2016−September 30, 2019). [2] A gap in enrollment up to 45 days was allowed in the pre‐index, while no gap in enrollment was allowed in the post‐index period. [3] First claim observed in the identification period is for MIRA (or AM) medication, and there is absence of MIRA (or AM) claims in the pre‐index period. AM, antimuscarinic; CFI, Claims‐based Frailty Index; MIRA, mirabegron.

Figure 2

Kaplan−Meier plots of persistence by index medication for matched cohorts (with number of patients with index medication). Abbreviations: AM, antimuscarinic; MIRA, mirabegron.