ECONOMIC AND CLINICAL IMPACT OF SWITCHING FROM ANTIMUSCARINICS TO MIRABEGRON FOR THE TREATMENT OF OVERACTIVE BLADDER

Purpose: Until recently pharmacological overactive bladder (OAB) treatment consisted exclusively of antimuscarinics, a subclass of anticholinergics (AC). Mirabegron, a new β-3 adrenergic agonist, is approved for the treatment of OAB patients, including those ineligible due to anticholinergic burden per the Beers criteria or intolerant of antimuscarinics due to adverse events (AEs). This study’s purpose was to develop and analyze a model to quantify the economic and clinical outcomes associated with wider use of mirabegron for the treatment of OAB from the perspectives of US commercial and Medicare Advantage payers.

Method: A prevalence-based model with a three-year horizon provided annual costs and estimated AE counts for increased use of mirabegron by switching from antimuscarinics. Patients not currently undergoing OAB pharmacotherapy can be modeled but are not included in these results. Adverse events comorbid with OAB included depression, falls and fractures, skin rashes, and urinary tract infections. Identical OAB comorbidity rates were assumed for patients on mirabegron as on anticholinergics, but comorbidities were higher in untreated patients. Antimuscarinic-related AEs included dry mouth, constipation, blurry vision, and cognitive decline.

Result: The model estimated numbers of patients who were currently treated with pharmacotherapy per million members to be 9,338 for a commercial plan and 16,547 for Medicare Advantage. Base case analysis found that for patients switching to mirabegron, increased prescription costs were largely offset by a decrease in medical costs. The table shows annual incremental results for populations in a million member plan where a projected number of patients currently treated with antimuscarinics switch to mirabegron.

Conclusion:

The analysis suggested that the increased use of mirabegron had a low budget impact on commercial and a moderate impact on Medicare payers. However, long-term clinical outcomes and variability in patient demographics should also be considered in formulary decisions. With an elderly population at greater risk from anticholinergic burden and its associated adverse events, mirabegron could play a role in plans with an older member mix.

 

	New Mirabegron Patients	Number of AEs Avoided	Incremental Cost PMPM ($)
Medicare Advantage  Year 1	132	41	0.011
Medicare Advantage  Year 2	430	132	0.036
Medicare Advantage  Year 3	811	250	0.069
Commercial Year 1	75	23	0.006
Commercial Year 2	243	75	0.019
Commercial Year 3	458	141	0.037