Discontinuation or poor adherence to antipsychotics in patients with schizophrenia may lead to relapses. Compared with daily administered antipsychotics (e.g., paliperidone extended-release (ER)), long-acting injectable antipsychotics (LAI) can improve medication adherence, resulting in a lower risk of relapse. Paliperidone palmitate, a new form of LAI, can be administered monthly (PP1M), three monthly (PP3M), or six-monthly (PP6M). While proven effective in improving compliance, the economic value of administering this high-cost treatment is unknown. This study compared the cost-effectiveness across PP6M, PP3M, PP1M, and paliperidone ER.

A Markov model was developed to simulate a cohort of patients with schizophrenia transitioning through the stable state, relapse with hospitalization, relapse without hospitalization, and death on a quarterly basis over a 3-year time horizon. Costs for paliperidone formulations were estimated using their average wholesale price, and costs for treating complications were estimated from previous literature. All costs were estimated from the U.S. healthcare system perspective and standardized to 2021 U.S. dollars. Quality-adjusted life-years (QALYs) were estimated using data from randomized controlled trials and previous literature. All input parameters varied from 75 to 125% of their base-case value in the sensitivity analyses.

Paliperidone ER is the most cost-effective when compared with PP1M (INB -$19,770), PP3M (INB -$522), and PP6M (INB -$19,470). When focusing on LAIs, PP3M is dominant compared with PP1M or PP6M. One-way sensitivity analyses show that PP3M may be cost-effective over paliperidone ER under certain circumstances, and the comparison between PP1M and PP6M remains inconclusive.

Paliperidone LAIs are not cost-effective compared with paliperidone ER, suggesting that their benefits may not outweigh the high administration costs. Among paliperidone LAIs, PP3M has a preferable economic value over PP1M and PP6M. However, this conclusion is drawn based on results from clinical trials and might not be generalizable to real-world settings.