OBJECTIVES:

To assess cost-effectiveness among long-acting injectable (LAI) paliperidone formulations administered every month (PP1M), 3 months (PP3M), or 6 months (PP6M) and oral paliperidone extended-release (ER).

METHODS:

A Markov model was developed to simulate 1,000 US adults with stable schizophrenia transitioning among stable-adherent, stable-nonadherent, relapse-inpatient, relapse-outpatient, and death states every 3 months for 5 years. Patients were stabilized with ER or PP1M and received one of the four treatment strategies including (1) continuing ER, (2) continuing PP1M, (3) switching to PP3M, and (4) switching to PP6M. Transition probabilities were estimated using relapse rates from clinical trials and adherence, hospitalization rate, and discharge rate from observational studies. Drug costs (average wholesale prices), medical costs, and utility values were derived from published sources. All costs were estimated from the U.S. healthcare system perspective and standardized to 2022 U.S. dollars. We reported incremental net benefits (INBs) between alternative formulations at the $50,000 willingness-to-pay threshold, with a positive value indicating cost-effectiveness. Deterministic and probabilistic sensitivity analyses were performed to test the model robustness.

RESULTS:

PP1M (INB −$79,949), PP3M (−$39,441), and PP6M (−$32,006) were not cost-effective compared with ER. Among LAI formulations, PP6M was cost-saving with the most quality-adjusted life year (QALY) gained (cost $109,466, QALY 3.95), followed by PP3M ($116,846, 3.94) and PP1M ($152,515, 3.85). The results were generally robust in sensitivity analysesThe probabilities of PP1M, PP3M, and PP6M being cost-effective over ER were 0%, 6.6%, and 8.8%. The probability of PP6M being cost-effective over PP1M and PP3M were 92.6% and 57.1%, respectively, and 65.2% of PP3M use was cost-effective over PP1M.

CONCLUSIONS:

For adults with stable schizophrenia, LAI paliperidone formulations were not cost-effective compared to ER, suggesting the high drug costs for LAI may not justify the improved quality of life. Among LAI formulations, PP6M is cost-effective compared to PP1M and PP3M.