Cost-effectiveness of pramipexole in addition to mood stabilisers for patients with treatment-resistant bipolar depression: Economic evaluation of the PAX-BD randomised controlled trial.

BACKGROUND: People with bipolar disorders (BD) frequently experience depressive symptoms that do not respond to available treatment options. The resulting burden for people with BD and society is substantial. This study sought to explore the cost-effectiveness of pramipexole in combination with mood stabilisers for people with treatment-resistant bipolar disorder (TRBD). METHODS: We calculated mean incremental cost ratios (ICER) of pramipexole compared to placebo over 12 and 48 weeks from health and social care (NHS + PSS) and societal perspectives for 36 participants with TRBD. Quality-adjusted life years (QALY) were captured with the EQ-5D-5L as the primary outcome measure. We used capability well-being measures (ICECAP-A, OxCAP-MH) to assess the robustness of the results and multiple imputation and bootstrapping to address missing data and small sample size. RESULTS: We found that pramipexole is more effective and cost-saving from the NHS + PSS perspective. The probability of being cost-effective at £30,000/QALY gained was 70 % (12 weeks) and 90 % (48 weeks). From the societal perspective, pramipexole was more effective but also more expensive with lower probability of cost-effectiveness (33 % at 12 weeks and 47 % at 48 weeks). Uncertainty around the mean ICERs was substantial due to the small sample size. LIMITATIONS: The PAX-BD trial was conducted during the COVID-19 pandemic and terminated early, resulting in a limited generalizability of resource use outside the pandemic context and a small sample size. CONCLUSIONS: Pramipexole is a cost-effective treatment option for TRBD from the NHS + PSS perspective, with statistically significant increases in health-related quality of life and capability well-being over extended periods.