Cost-utility analysis of deep brain stimulation surgery plus best medical therapy versus best medical therapy in patients with Parkinson's: Economic evaluation alongside the PD SURG trial

INTRODUCTION:
Williams and colleagues reported that DBS surgery for patients with advanced PD improves motor function and quality of life compared to best medical therapy alone at 1 year, but with surgery-related side effects in a minority. This article reports on the economic evaluation alongside this trial.
METHODS:
Detailed resource use and quality of life over 12 months after randomization was obtained from the trial reported by Williams and colleagues. Outcomes were measured using the EQ-5D and quality-adjusted life years calculated.
RESULTS:
Year 1 costs for surgery were significantly higher than in best medical therapy, at £19,069 compared to £9,813, a difference of £9,256 (95% confidence interval [CI]: £7,625, £10,887). There was a small, significant gain in utility at 1 year but a statistically insignificant gain of 0.02 quality-adjusted life years (95% CI: -0.015, 0.05) in the surgical arm. The incremental cost per quality-adjusted life year of surgery at 1 year was £468,528. Extrapolation reveals that after 5 years, this ratio is likely to reduce to £45,180, but subsequently rise to £70,537 at 10 years owing to the increased probability of battery replacements (and re-replacements) beyond 5 years.
CONCLUSION:
In this patient group, DBS is not cost-effective at 1 year. Extrapolation, however, reveals an increasing likelihood of cost-effectiveness up to 5 years and reducing cost-effectiveness between 5 and 10 years. These models are sensitive to assumptions about future costs and quality-adjusted life years gained.