Background and objective: Long-acting injectable antipsychotics (LAIs) are associated with better treatment adherence and persistence than oral antipsychotics (OAPs) in patients with schizophrenia. However, real-world evidence assessing the impact of treatment with LAIs in Germany is limited. To fill this gap, we compared antipsychotic medication adherence and risk of treatment discontinuation (TD) among schizophrenia patients newly initiated on LAI or who switched their OAP regimen (overall cohort; OC).
Methods: Claims data of German schizophrenia patients who initiated LAIs or switched their OAP during 2012-2016 (index date) were retrospectively analyzed. Treatment switch was defined as add-on medication to existing prescription or terminating the existing prescription and initiating another OAP. Adherence and time to treatment discontinuation (TTD) were estimated. Determinants of treatment discontinuation were analyzed using two Cox regression models. Model 1 controlled for age, sex, and Charlson Comorbidity Index (CCI); model 2 also included insurance status, and medication, visit, and psychiatric inpatient stay costs. Sensitivity analysis on patients who terminated existing prescriptions and initiated new OAPs (complete switch cohort; CSC) was performed.
Results: In OC (n = 2650), LAI users had better adherence (35.4% vs. 11.6%), persistence (no 60-day gap; 40.7% vs. 19.8%), and longer TTD (median [95% confidence interval (CI)] 216 [193-249] vs. 50 [46-56] days) than OAP users. OAP usage (hazard ratio [HR] 1.89, 95% CI 1.73-2.06; p < 0.001) and greater CCI (HR 1.04, 95% CI 1.00-1.07; p = 0.023) were associated with greater risk of TD in model 1. Model 2 showed similar results. LAI users in CSC also had better adherence, persistence, and longer TTD. In CSC too, OAP usage and greater CCI were associated with greater risk of TD in model 1, but only CCI was significant in model 2. Higher pre-index psychiatric inpatient costs were associated with lower risk of TD (HR 0.99, 95% CI 0.98-1.00; p = 0.014).
Limitations: Inherent limitations of claims data and lack of control on OAP administration may have influenced the results.
Conclusion: This real-world study associates LAIs with better medication adherence and lower antipsychotic discontinuation risk than OAPs.