Assessing the Impact of Time-Dependent Treatment With Once-Monthly Paliperidone Palmitate or Oral Atypical Antipsychotics on Healthcare Resource Utilization and Medicaid Spending Among Patients With Schizophrenia Using Marginal Structural Models

Objective: To assess the impact of time-dependent (TD) treatment with paliperidone palmitate (PP) versus oral atypical antipsychotics (OAAs) on healthcare resource utilization and costs among patients with schizophrenia.

Methods: A retrospective longitudinal study was conducted using Medicaid claims data from 4 states. Adults with schizophrenia with ≥2 claims for PP or the same OAA within 90 days between 01/2010-03/2012 were identified (the first claim served as the index date). Baseline information was collected during the 6 months pre-index whereas information on TD treatment, TD covariates and the outcomes of interest was assessed quarterly during follow-up. Marginal structural models (MSMs) were used to estimate the effects of TD treatment (PP versus OAAs) on healthcare resource utilization and costs while controlling for baseline and TD confounders.

Results: Among 13,126 patients, 952 and 12,174 comprised the PP and OAA cohorts. During follow-up, 5% of patients switched between PP and OAAs. Using MSMs, PP was associated with lower incidence rates of all-cause emergency room visits (incidence rate ratio [IRR]=0.85 [P=0.04]) and schizophrenia-related long-term care admissions (IRR=0.42 [P=0.04]). In addition, PP treatment was found to significantly reduce total direct medical costs, compared to OAA treatment (mean monthly cost difference [MMCD] = -$256 [P=0.01]), which offsets the higher pharmacy expense associated with PP treatment (MMCD= $122 [P<0.01]). Total healthcare pharmacy and medical cost did not differ between the two treatments (MMCD= -$91 [P=0.69]).

Conclusion: Although higher pharmacy costs were observed among PP treated patients, total healthcare costs did not differ relative to OAA treated patients.