Objective: To evaluate the costs and outcomes associated with different sequences of oral anti-muscarinic agents and the selective β(3)-adrenoceptor agonist, mirabegron, for the treatment of overactive bladder (OAB).
Methods: A Markov model with monthly cycle length and time horizon up to 3 years was designed to compare two different sequences of up to three lines of oral therapy for OAB. Patients who discontinued one oral medication could switch to another oral medication or could discontinue treatment. Patients whose symptoms were not controlled were considered for botulinum toxin or sacral nerve stimulation. Outcomes were measured by (a) number of patients with controlled symptoms (no incontinence episodes and <8 micturitions per 24 h); (b) patients with no incontinence episodes per 24 hours; and (c) patients with <8 micturitions per 24 h.
Results: Including a third-line oral medication before considering other treatment options improved all patient outcomes, irrespective of the specific drugs used. A three-line sequence including two generic (oxybutynin first line and tolterodine extended-release second line) and one branded drug (solifenacin 5 mg third line) resulted in inferior patient outcomes at costs similar to a sequence of branded drugs (mirabegron first line, solifenacin 5 mg second line, solifenacin 10 mg third line): controlled patients (generic 29.6/1000 vs branded 38.7/1000); patients with no incontinence episodes (103.6/1000 vs 123.7/1000); patients with <8 micturitions (228.7/1000 vs 262.1/1000). Annual treatment costs per patient were similar (generic £1299 vs branded £1385).
Conclusions: In the treatment of OAB, low-cost generic treatments are not necessarily more cost-effective than branded drugs, primarily because a better efficacy and tolerability balance improves both symptom control and persistence.
Keywords: Anti-muscarinic agents; Markov model; Mirabegron; Overactive bladder; Pharmacoeconomics.