OBJECTIVES: Improving treatment continuity and adherence to antipsychotic therapy in schizophrenia is a major challenge. The 3-monthly long-acting therapy of paliperidone palmitate (PP3M) has the longest dosing interval available compared to other antipsychotics whilst having the same active ingredient, as the existing 1-monthly long-acting therapy (PP1M). This study assessed the cost-effectiveness of PP3M versus PP1M in patients with schizophrenia in the UK.

METHODS: A Markov model with monthly cycles encompassed a first treatment line (PP3M or PP1M) followed by a period off-treatment, and then a follow-up therapy (a mix of treatments reflecting UK practice). At each cycle, patients could either remain in stable disease, experience a relapse, experience temporary or permanent adverse events, or die. Relapse and adverse event rates were based on a non-inferiority head-to-head trial and were set equal in both arms; first line treatment discontinuation of PP1M was based on UK real-world evidence and assumed equivalent for PP3M. Accounting for differences in drug exposure length between PP1M and PP3M, a time-dependent relapse rate was applied during the period off-treatment. The benefits of a reduced administration frequency were reflected in the stable state utility for PP3M by applying an increment to the PP1M baseline utility. The perspective of the UK National Health Service was adopted throughout a two-year time horizon. Costs and effects were discounted at an annual rate of 3.5%.

RESULTS: PP3M is dominant compared to PP1M, showing cost savings (£ -638) and an increase in QALYs (+0.069). Cost savings were driven by reductions in relapse and administration costs for PP3M, whilst QALY gains were derived from the reduced administration frequency. Results robustness was demonstrated via sensitivity and scenario analyses.

CONCLUSIONS: The introduction of PP3M to the UK setting constitutes an improvement, bringing savings and QoL benefits to the current LAI-based standard of care for schizophrenia patients.