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 < 0.001) on the index medication as well as less use of other psychiatric medications, compared to OAAs. Adherence findings were similar for the overall cohort. Among recently diagnosed patients, lower medical costs associated with PP1M (MMCD = $-466; P = 0.028) outweighed the higher pharmacy costs (MMCD = $322; P < 0.001) resulting in similar total healthcare costs across groups (MMCD = $-144; P = 0.553). Overall, findings were similar but there was a trend toward a lower magnitude of medical cost savings (MMCD = $-286; P < 0.001). Reductions in medical costs were mainly driven by reductions in inpatient days (recently diagnosed RR = 0.85, P = 0.353; overall RR = 0.84, P = 0.004) and in home care visits (recently diagnosed RR = 0.43, P = 0.008; overall RR = 0.78, P = 0.048). CONCLUSIONS: PP1M patients demonstrated significantly lower medical costs offsetting higher pharmacy costs relative to OAA patients. Recently diagnosed patients using PP1M may have greater medical cost savings relative to OAAs than that observed in the overall population, highlighting the potential economic impact of PP1M in adults recently diagnosed with schizophrenia.