Cost-effectiveness of long-acting injectable paliperidone palmitate versus haloperidol decanoate in maintenance treatment of schizophrenia

Objective: This study assessed the relative cost-effectiveness of haloperidol decanoate (HD), a first-generation long-acting injectable (LAI) antipsychotic, and paliperidone palmitate (PP), a second-generation LAI antipsychotic. Methods: A double-blind, randomized 18-month clinical trial conducted at 22 clinical research sites in the United States compared the cost-effectiveness of HD and PP among 311 adults with schizophrenia or schizoaffective disorder who had been clinically assessed as likely to benefit from an LAI antipsychotic. Patients were randomly assigned to monthly intramuscular injections of HD (25-200 mg) or PP (39-234 mg) for up to 24 months. Quality-adjusted life years (QALYs) were measured by a schizophrenia-specific algorithm based on the Positive and Negative Syndrome Scale and side-effect assessments; total health care costs were assessed from the perspective of the health system. Results: Mixed-model analysis showed that PP was associated with .0297 greater QALYs over 18 months (p=.03) and with $2,100 more in average costs per quarter for inpatient and outpatient services and medication compared with HD (p<.001). Bootstrap analysis with 5,000 replications showed an incremental cost-effectiveness ratio for PP of $508,241 per QALY (95% confidence interval=$122,390-$1,582,711). Net health benefits analysis showed a .98 probability of greater cost-effectiveness for HD compared with PP at an estimated value of $150,000 per QALY and a .50 probability of greater cost-effectiveness at $500,000 per QALY. Conclusions: HD was more cost-effective than PP, suggesting that PP's slightly greater benefits did not justify its markedly higher costs, which are likely to fall once the medication's patent expires.