Adherence, healthcare resource utilization and Medicaid spending associated with once-monthly paliperidone palmitate versus oral atypical antipsychotic treatment among adults recently diagnosed with schizophrenia

Abstract Background Once-monthly paliperidone palmitate (PP1M) is a long-acting injectable antipsychotic that may increase adherence rates, reduce hospitalizations, and lower medical costs compared to oral atypical antipsychotics (OAAs) among schizophrenia patients. However, the impact of PP1M in recently diagnosed patients remains unknown. The present study compared adherence, healthcare resource utilization and Medicaid spending between schizophrenia patients initiating PP1M versus OAA, among patients recently diagnosed (defined using ages 18–25 years as a proxy) and among the overall population. Methods Medicaid data from five states (09/2008–03/2015) were used to identify adults with schizophrenia initiated on PP1M or OAAs (index date) on or after 09/2009. Outcomes were compared between PP1M and OAA groups following inverse probability of treatment weighting (IPTW). Univariate linear and Poisson regression models with nonparametric bootstrap procedures were used to compare the 12-month healthcare resource utilization and costs using rate ratios (RRs) and mean monthly cost differences (MMCDs), respectively. Results Overall, patients initiated on PP1M (N = 2053) were younger (mean age: 41 vs. 44 years) and had more baseline antipsychotic use (88% vs. 62%) compared to OAA patients (N = 22,247). IPTW resulted in balanced baseline characteristics. Among recently diagnosed patients, PP1M was associated with better adherence (PDC ≥ 80%: 29% vs. 21%, P