Pharmacoeconomic analysis of paliperidone palmitate versus olanzapine pamoate for chronic schizophrenia in Norway.

OBJECTIVE: Paliperidone palmitate long-acting injection (PP-LAI) has recently been approved for treatment of chronic schizophrenia. Its cost-effectiveness has not been established. The objective was to compare direct costs and outcomes between PP-LAI and olanzapine pamoate (OLZ-LAI) in treating chronic schizophrenia in Norway from the perspective of the government payer.

METHODS: We used a decision analytic model over a 1-year time horizon. Clinical inputs were derived from the literature and an expert panel; costs were taken from standard lists, adjusted to 2010 Norwegian kroner (NOK). Discounting was not done. Main outcomes included average cost per patient treated, hospitalisations, emergency room (ER) visits and quality-adjusted life years (QALYs). The pharmacoeconomic outcome was the incremental cost per QALY. Robustness was examined using one-way sensitivity analyses on critical variables and a 5000-iteration probabilistic Monte Carlo sensitivity analysis with all variables included.

RESULTS: PP-LAI generated 0.845 QALY at a cost of 151 336 NOK of which 23% was due to drugs; 25% of patients were hospitalised and another 12% required ER visits. OLZ-LAI cost 174 351 NOK (21% due to drugs); patient outcomes included 0.844 QALY, 27% hospitalisations and 14% ER visits. PP-LAI dominated OLZ-LAI in the base case. The analysis was reasonably robust against variations in drug cost but sensitive to small changes in adherence and hospitalisation rates. Overall, PP-LAI was dominant over OLZ-LAI in 54.5% of simulations. Replacing OLZ-LAI with PP-LAI would be cost saving for the Norwegian healthcare system.

CONCLUSION: PP-LAI was cost-effective compared with OLZ-LAI in treating patients with chronic schizophrenia in Norway but sensitive to changes in adherence and hospitalisation rates.