Prevalence of Concomitant Medications Among Patients with Schizophrenia Prescribed Atypical Antipsychotics

Introduction Typical and atypical antipsychotics (AAPs) are the main treatment options among patients with schizophrenia. However, AAPs have been associated with several side effects and comorbid conditions. To manage side effects, often patients are prescribed concomitant medications to manage their condition, increasing polypharmacy. Though common in practice, the prevalence of concomitant medication use in patients with schizophrenia is not well established. This study evaluated the annual prevalence of concomitant medications among patients with schizophrenia who were prescribed AAPs. Methods This retrospective study was conducted using the PharMetrics database (01/2019 – 12/2021). Patients were included in the analyses if they had a diagnosis of schizophrenia, were continuously enrolled in pharmacy and medical claims for the full year and were prescribed AAPs. A sensitivity analysis was also conducted among patients who demonstrated ≥50% adherence to their prescribed AAPs (with a grace period of 30 days). For both the main and sensitivity analyses patient populations, the concomitant drugs prescribed were labeled at the drug class (GPI2) and generic drug level. Prevalence for drug class and each drug was calculated as a percentage of patients who were prescribed ≥1 of the agent among those who met the inclusion and exclusion criteria within the given year. Results For the year 2019, 2020 and 2021, 12,360; 13,242 and 14,780 patients met the inclusion and exclusion criteria, respectively. The mean age of the cohort ranged from 43.5 - 45.4 years. Patients were predominantly male and commercially insured. Antidepressants were the most prevalent concomitant medication prescribed (2019: 61.2%, 2020: 61.2%, 2021: 62.0%). Other highly prevalent drug classes identified were - anticonvulsants (2019: 44.2%, 2020: 44.5%, 2021: 45.0%), antianxiety agents (2019: 36.3%, 2020: 37.6%, 2021: 38.9%), antihyperlipidemics (2019: 26.3%, 2020: 28.1%, 2021: 30.7%), antihypertensives (2019: 25.7%, 2020: 27.2%, 2021: 28.1%), antiparkinson agents (2019: 61.2%, 2020: 61.2%, 2021: 62.0%), anticholinergics (2019: 61.2%, 2020: 61.2%, 2021: 62.0%) and analgesics (2019: 61.2%, 2020: 61.2%, 2021: 62.0%). At the individual drug level, benzotropine mesylate (2019: 19.5%, 2020: 18.7%, 2021: 18.8%), atorvastatin (2019: 14.5%, 2020: 16.7%, 2021: 18.4%), lorazepam (2019: 14.1%, 2020: 14.7%, 2021: 14.3%), gabapentin (2019: 13.7%, 2020: 13.9%, 2021: 14.8%), and metformin (2019: 13.2%, 2020: 13.7%, 2021: 15.4%) were the most prevalent prescribed concomitant medications. There was no difference when similar analyses were conducted in the adherent patient population. Conclusions These results indicate a high prevalence of concomitant antidepressants, antihyperlipidemics, antihypertensives and anticholinergics among patients with schizophrenia who are prescribed AAPs. Funding Sumitomo Pharma America Inc.