Trends in Medicare Coverage of Overactive Bladder Medications in the U.S

Objectives: To identify trends in Medicare coverage of common overactive bladder (OAB) medications in the United States, specifically for provider-preferred medications of trospium, mirabegron, and vibegron compared to medications with a greater risk of cognitive dysfunction (oxybutynin, tolterodine, fesoterodine, darifenacin, and solifenacin).

Methods: Using the 2021 National Association of Insurance Commissioners Market Share Report, the top six American insurers offering Medicare Advantage plans and Special Needs Plans were identified. Publicly-available formulary information was located though insurers’ websites. Medication coverage tiers and direct consumer cost information for the initial stage of coverage was accessed from December 2023 through March 2024 for all available plans located in the most populous zip codes within each geographical coverage area according to 2021 U.S. Census data. For all plans, lower tier coverage represented lower consumer costs. Coverage for the following medications were investigated: oxybutynin instant-release (IR) 5mg, oxybutynin extended-release (ER) 5mg, tolterodine IR 1mg, tolterodine ER 2mg, fesoterodine ER 4mg, darifenacin 7.5mg, solifenacin 5 mg, trospium IR 20mg, trospium ER 60mg, mirabegron 25mg, and vibegron 75mg. Coverage scores (a weighted average of associated coverage tiers for individual or grouped medication(s)) were generated relative to the number of plans for each state or insurer. A lower coverage score indicated better coverage (range 0.2-1.0).

Results: Medication coverage for 1,617 insurance plans from 50 states and the District of Columbia representing an estimated 47% market share were evaluated. The average coverage scores across all plans were as follow: oxybutynin IR (0.4), oxybutynin ER (0.42), tolterodine IR (0.57), tolterodine ER (0.75), fesoterodine ER (0.78), darifenacin (0.81), solifenacin (0.51), trospium IR (0.60), trospium ER (0.89), mirabegron (0.68), and vibegron (0.73). Oxybutynin IR had the best medication coverage across insurers while trospium ER had the worst (x^2 = 831.05, d.f. = 1, p < 0.001; x^2 = 354.76 d.f. = 1, p < 0.001). The preferred medications had significantly worse coverage in comparison to non-preferred medications across all plans collectively (x^2 =2064.8, d.f. = 4, p < 0.001). The best coverage for provider-preferred medications was in Arkansas and Utah (see Figure 1). Centene had the best overall coverage for OAB medications in terms of coverage score and lowest overall initial cost for medication initiation while Aetna/CVS had the best coverage for provider-preferred medications by coverage score and initial consumer costs (see Figure 2).

Conclusions: Despite mounting evidence of adverse effects on cognition with prolonged anticholinergic use, beta-3 agonists remain in more expensive tiers across insurers nationwide. While up to 97% of the American population aged 65 or older take part in Medicare, current trends in Medicare coverage of OAB medications reveal a need for improved coverage of preferred medications for an aging population at higher risk of side effects.