Treatment Adherence and Health Care Utilization After a First Episode of Psychosis

Importance Few studies have examined medication adherence immediately after initiation of antipsychotics among young individuals experiencing their first episode of psychosis (FEP). Objectives To estimate adherence to antipsychotic medications and examine factors associated with adherence among commercially insured individuals with FEP. Design, Setting, and Participants This retrospective cohort study used administrative claims from the Merative MarketScan commercial health insurance database in the US from January 1, 2013, to December 31, 2021. The study included individuals aged 15 to 40 years with 12 months of continuous enrollment who had no prior diagnosis of psychosis and who subsequently experienced FEP and were prescribed antipsychotics. Eligible patients were followed up for 365 days after their first antipsychotic prescription. Data analysis was performed from September to December 2025. Exposure The proportion of days covered was used to calculate adherence, defined as the number of covered medication days divided by the 365-day follow-up period. Main Outcomes and Measures Health care utilization outcomes included outpatient visits, behavioral health outpatient visits, general hospitalization, psychiatric hospitalization, and emergency department (ED) visits. Log-binomial regressions were used to estimate the association between demographic and clinical factors and adherence rate, and negative binomial regressions were used to examine the association between antipsychotic adherence and health care utilization. Results This study included 11 889 individuals who experienced FEP (mean [SD] age, 22.7 [6.8] years; 6708 male [56.4%]). The overall adherence rate to antipsychotics among the FEP population was 19.1% (2270 of 11 889). Compared with other psychotic spectrum disorders, greater adherence to antipsychotics was found among individuals with schizophrenia (prevalence ratio [PR], 1.78; 95% CI, 1.57-2.04; P < .001) and those with mood disorders (PR, 1.21 [95% CI, 1.06-1.39; P = .005]). Moreover, individuals with better adherence tended to have fewer ED visits (incidence rate ratio [IRR], 0.85; 95% CI, 0.81-0.90; P < .001), more behavioral health outpatient visits (IRR, 1.53; 95% CI, 1.47-1.59; P < .001), and more general outpatient visits (IRR, 1.07; 95% CI, 1.02-1.13; P = .003). Conclusions and Relevance In this cohort study of individuals with FEP, adherence to antipsychotics was low, with 19.1% of individuals classified as adherent. Moreover, poor adherence to antipsychotics was associated with more ED visits. Low treatment adherence rates may be a hurdle for initiatives aiming to improve psychosis treatment outcomes.