Cost-utility analysis of levodopa carbidopa intestinal gel (Duodopa) in the treatment of advanced Parkinson's disease in patients in Scotland and Wales.

Aims: To carry out a cost-utility analysis comparing the cost-effectiveness of levodopa carbidopa intestinal gel (LCIG) with standard of care (SOC) in patients with advanced Parkinson's Disease (aPD) unsuitable for apomorphine or deep brain stimulation (DBS). LCIG is the only treatment option in this small, but clinically important, population.

Methods: A Markov model with 25 disease states based on disease stage and off-time status plus death. Patients enter the model with aPD spending >50% of their waking day in the off-state. Patients progress through the model in 6-monthly cycles for 20 years to approximate lifetime treatment and capture long-term costs and effects of therapy. Inputs are based on LCIG clinical trials for clinical outcomes and health state utilities, the literature for health state transitions and use UK-based input data wherever possible (drug costs, disease/adverse event management costs, discontinuation rates, mortality rates).

Limitations: Data collection can be challenging in this small, elderly population with advanced disease, therefore some model inputs were estimated, rather than collected directly. It was assumed that a reduction in off-time was the only benefit after the first year of treatment with LCIG; this is a conservative approach, since there may be additional clinical benefits.

Results: There is a considerable incremental gain in quality adjusted life years (QALYs) for patients treated with LCIG of 1.26 QALY with an associated incremental cost-effectiveness ratio (ICER) of £52,110. If the impact on caregivers is included, the ICER reduces to £47,266.

Conclusions: In cases where there is an orphan population, with no alternative treatment options, HTA assessments have a broader decision-making framework and the ICER is interpreted in this context. In the setting of a very small population, with considerable unmet need, LCIG represents value for money, as reflected by funding approval across the UK.