Antipsychotic Adherence, Resource Use, and Costs Before and After the Initiation of Once-monthly Paliperidone Palmitate Therapy Among Medicaid Beneficiaries With Prior Schizophrenia Relapse.

Purpose: Patients with schizophrenia often struggle with medication adherence and may benefit from the use of a long-acting injectable antipsychotic, including once-monthly paliperidone palmitate (PP1M), which was previously demonstrated to improve outcomes compared with oral antipsychotics. This study assessed the impact of initiating PP1M therapy on medication adherence, health care resource use (HRU), and costs among Medicaid beneficiaries with schizophrenia and a prior schizophrenia relapse.

Methods: A 6-state Medicaid database (from quarter 1 of 2009 to quarter 1 of 2018) was used to identify adults with ≥2 schizophrenia diagnoses who started PP1M therapy on or after January 1, 2010. The index date was the first PP1M claim. Patients had ≥12 months of continuous Medicaid enrollment before and after the index date, ≥1 oral antipsychotic claim in the 12 months before the index date, and ≥1 relapse (proxied as a schizophrenia-related inpatient admission or emergency department [ED] visit) during the 12 months before the index date. Generalized estimating equations were used to compare adherence to antipsychotics (proportion of days covered ≥80%), HRU, and costs (reported in 2018 US dollars) in the 12 months after versus before the index date. Sensitivity analyses were conducted (1) accounting for the minimum and cumulative price inflation Medicaid rebates for pharmacy costs of branded psychiatric medications, (2) among patients with ≥2, ≥3, and ≥4 prior schizophrenia-related inpatient admissions or ED visits, (3) among patients not adherent to antipsychotic treatment before the index date, and (4) among patients switching to PP1M directly from oral risperidone or paliperidone.

Findings: A total of 1725 patients met the study inclusion criteria (mean age, 39.5 years; 43% female). After versus before the index date, patients were 93% more likely to be adherent to antipsychotic treatment (P < 0.01). The likelihood of inpatient admissions and ED visits decreased by 89% and 49% (all P < 0.01) after initiating PP1M therapy. The number of inpatient days decreased by 31% (P < 0.01) and the number of ED visits by 16% (P = 0.03). Pharmacy costs increased by $514 per-patient-per-month (PPPM), whereas medical costs, driven by inpatient costs, decreased by $391 PPPM (all P < 0.01). Sensitivity analyses yielded similar trends. Notably, total health care cost savings of $231 PPPM were observed after accounting for the cumulative Medicaid rebate for costs of branded psychiatric medications (P < 0.01).

Implications: In Medicaid beneficiaries with relapsed schizophrenia, transitioning from oral antipsychotics to PP1M was associated with improved adherence to antipsychotics and decreased use of inpatient and ED services. Increased pharmacy costs after the initiation of PP1M were offset by decreased medical costs. After applying the cumulative Medicaid rebate, including the price inflation rebate for costs of branded psychiatric medications, initiation of PP1M therapy resulted in statistically significant health care cost savings.