Cost Effectiveness of Long-Term Incobotulinumtoxin-A Treatment in the Management of Post-stroke Spasticity of the Upper Limb from the Australian Payer Perspective

BACKGROUND: In Australia, the reimbursement of botulinum neurotoxin-A (BoNT-A) on the Pharmaceutical Benefits Scheme for the treatment of moderate to severe spasticity of the upper limb following a stroke (PSS-UL) is restricted to four treatment cycles per upper limb per lifetime. This analysis examined the cost effectiveness of extending the treatment beyond four treatments among patients with an adequate response to previous treatment cycles. METHODS: A Markov state transition model was developed to perform a cost-utility analysis of extending the use of incobotulinumtoxin-A beyond the current restriction of four treatment cycles among patients who have shown a successful response in previous treatment cycles (’known responders’). The Markov model followed patients in 12-weekly cycles for 5 years, estimating the proportion of patients with or without response over this period in each of the modelled treatment arms. Post hoc analysis of an open-label extension phase study informed the Markov model. The perspective of the analysis was the Australian healthcare system, meaning only direct healthcare costs were included. Utility values by response status were derived from EQ-5D data from a published double-blind, placebo-controlled study. The primary outcome measure was the incremental cost per quality-adjusted life-year (QALY). Univariate and probabilistic sensitivity analyses were conducted. RESULTS: The open-label extension study data demonstrated the probability of treatment response after four injections was greater among ‘known responders’ than those without prior response. The incremental cost per QALY gained of continued use of incobotulinumtoxin-A beyond the current restriction of four treatments was A$59,911. CONCLUSION: Limiting BoNT-A treatment to four cycles per patient per lifetime is likely to be suboptimal in many patients with PSS-UL. Treatment response beyond four cycles is highest among known responders, and allowing such patients to continue treatment beyond four cycles appears cost effective.