Real-World Adherence and Discontinuation of Oral Antipsychotics and Associated Factors in a National Sample of US Medicare Beneficiaries with Schizophrenia.

Purpose: Little is known about adherence to and discontinuation of newly initiated oral antipsychotics (OAPs) as well as associated factors among Medicare beneficiaries with schizophrenia. This study aimed to examine rates of OAP adherence and discontinuation and associated factors in a national sample of fee-for-service Medicare beneficiaries with schizophrenia.

Patients and methods: This retrospective study used 100% fee-for-service Medicare claims data to identify adult beneficiaries with schizophrenia, initiating a new OAP between 01/01/2017 and 12/31/2019 (index date = date of new OAP prescription). Outcomes included adherence and discontinuation. Factors associated with adherence were assessed using logistic and linear regressions; Cox regressions were used to assess factors associated with discontinuation.

Results: In our final sample of 46,452 Medicare beneficiaries with schizophrenia, 35.4% were adherent to their newly initiated OAP (mean [SD] PDC: 0.52 [0.37]) over 12 months after initiation. Most patients (79.4%) discontinued their new OAP (median [IQR] time to discontinuation: 3.6 (1.0, 9.9) months). Factors associated with lower odds of adherence included younger age (OR: 0.43; 95% CI: 0.40-0.47, p <0.001 for patients aged 18-35 relative to patients aged ≥65 years); non-White race (OR: 0.72; 95% CI: 0.69-0.75, p <0.001 relative to White patients); and evidence of prior schizophrenia-related hospitalization (OR: 0.80; 95% CI: 0.77-0.83, p <0.001 relative to patients without evidence of prior schizophrenia-related hospitalization). Similar associations were observed for discontinuation outcomes. Twice-daily dosing frequency was also associated with lower odds of adherence (odds ratio [OR]: 0.93; 95% CI: 0.89-0.97, p = 0.0014) and higher hazard of discontinuation (hazard ratio [HR]: 1.03; 95% CI: 1.00-1.05, p = 0.0244) relative to once-daily dosing frequency.

Conclusion: We found high rates of non-adherence and discontinuation among Medicare beneficiaries initiated on currently available OAPs. We also identified risk factors that contribute to increased odds of medication non-adherence. By identifying at-risk patient populations, targeted interventions can be initiated to facilitate treatment continuity.