Projecting the economic outcomes of switching patients with schizophrenia from oral atypical antipsychotics to once-monthly, once-every-3-months, and once-every-6-months paliperidone palmitate

Preliminary data from a 4-year mirror-image and multicentre study of patients initiating paliperidone palmitate 6-monthly long-acting injectable antipsychotic: the Paliperidone 2 per Year study

Background

Paliperidone palmitate 6-monthly (PP6M) is the first long-acting antipsychotic injectable (LAI) to allow for only two medication administrations per year, though there is presently limited insight into its effectiveness and potential added value in real clinical practice conditions.

Objectives

To present our ongoing study and draw its preliminary data on patient characteristics initiating PP6M and adherence during the first year of treatment.

Methods

The paliperidone 2 per year (P2Y) study is a 4-year, multicentre, prospective mirror-image pragmatic study taking place at over 20 different sites in Europe. The mirror period covers 2 years either side of the PP6M LAI initiation. Retrospective data for the previous 2 years are collected for each patient from the electronic health records. Prospective data are recorded at baseline, 6, 12, 18 and 24 months of drug administration and also cover information on concomitant psychiatric medication, relapses, hospital admissions, side effects, discontinuation and its reasons. Meanwhile, here we present preliminary data from the P2Y study at basal and 6-month period (first and second PP6M administration).

Results

At the point of PP6M initiation, the most frequent diagnosis was schizophrenia (69%), the clinical global impression scale mean score was 3.5 (moderately markedly ill) and the rate of previous hospital admissions per patient and year was 0.21. PP6M was initiated after a median of 3-4 years on previous treatment: 146 (73%) from paliperidone palmitate 3-monthly, 37 (19%) from paliperidone palmitate 1-monthly and 17 (9%) from other antipsychotics. The mean dose of the first PP6M was 1098.9 mg. The retention rate at 6 months and 1 year of treatment on PP6M in our cohort was 94%.

Conclusion

Patient and clinician preference for LAIs with longer dosing intervals was the main reason for PP6M initiation/switching resulting in high treatment persistence. Future data are needed to evaluate the full impact of PP6M in clinical practice.

Cost-effectiveness analysis of monthly, 3-monthly, and 6-monthly long-acting injectable and oral paliperidone in adults with schizophrenia

BACKGROUND: Paliperidone is among the most cost-effective antipsychotics in adults with schizophrenia, and it has different formulations, including oral paliperidone extended-release (ER) and long-acting injectable (LAI) paliperidone formulations administered every month (PP1M), 3 months (PP3M), or 6 months (PP6M). However, cost-effectiveness analyses comparing different paliperidone formulations were limited. OBJECTIVE: To compare the cost-effectiveness across different paliperidone formulations. METHODS: A Markov model was developed to simulate 1,000 adults aged 40 years with stable schizophrenia transitioning among stable disease-medication adherent, stable disease-medication nonadherent, relapse with hospitalization, relapse with ambulatory care, and death states every 3 months for 5 years. Drug costs were estimated using the prices listed in the Veterans Affairs Federal Supply Schedule, and costs for treating complications were estimated from published studies. All costs were estimated from the US health care system perspective and standardized to 2022 US dollars using the Consumer Price Index Inflation Calculator. Quality-adjusted life-years (QALYs) were estimated using relapse rates from randomized clinical trials and health-related quality of life scores from observational studies. The estimated future costs and QALYs were discounted at 3%. We reported incremental net monetary benefits between alternative formulations at the $50,000 willingness-to-pay (WTP) threshold with a positive value indicating cost-effectiveness. The impact of parameter uncertainty on study outcomes was assessed using 1-way deterministic and probabilistic sensitivity analyses. RESULTS: In adults with schizophrenia stabilized with paliperidone ER, switching to LAI formulations was associated with increased QALY (PP1M = 0.05, PP3M = 0.14, PP6M = 0.15) and increased cost (PP1M = 49,433, PP3M = 26,698, PP6M = 26,147), leading to a negative incremental net monetary benefit (PP1M = -$46,804, PP3M = -$19,508, PP6M = -$18,886) compared with continuing ER. Among LAI formulations, PP6M was cost-saving with the most QALYs gained (cost = $63,277, QALY = 3.731), followed by PP3M (cost = $63,828, QALY = 3.729) and PP1M (cost = $86,563, QALY = 3.638). At the $50,000 WTP threshold, the probabilities for PP1M, PP3M, and PP6M being cost-effective compared with paliperidone ER were 0.4%, 10.2%, and 9.8%, respectively. The probability of PP6M being cost-effective was 92.6% for the PP6M-PP1M pair and 55.2% for the PP6M-PP3M pair, and 91.1% of PP3M use was cost-effective in the PP3M-PP1M pair. The results were generally robust in the sensitivity analyses, even at the $190,000 WTP threshold. CONCLUSIONS: For patients with schizophrenia stabilized with paliperidone ER, switching to LAI formulations was not cost-effective, suggesting the high drug costs for LAI may not justify the improved quality of life within 5 years. Among LAI formulations, PP6M was cost-effective over PP1M and PP3M.