Disease Prevalence, Comorbid Conditions, and Medication Utilization Among Patients with Schizophrenia in the United States

Abstract

Disease prevalence, comorbid conditions, and pharmacological treatments were examined in a large population of US commercial- or Medicaid-insured individuals with schizophrenia. This retrospective, cross-sectional claims analysis sourced data from the IBM MarketScan Commercial and Medicare Supplemental Databases and the Multi-state Medicaid Database (01Jan2009 to 30Jun2016). Cases were defined by =1 diagnostic claim (ICD-9-CM/ICD-10-CM) for schizophrenia during the study period. Comorbidities (=1 ICD-9-CM/ICD-10-CM diagnosis code) were grouped according to Clinical Classifications Software (CCS) level 2 categories. For the per-database analysis of comorbidities, schizophrenia cases were matched with controls by demographic characteristics. Case-control comorbidity comparisons were performed using prevalence rate ratios (PRRs) and 95% CIs. Per-database medication exposure (=1 National Drug Code in outpatients grouped by Redbook classification) was also assessed. Schizophrenia prevalence was 0.11% and 0.99% in commercially and Medicaid-insured patients, respectively. In both databases, comorbidity prevalence was higher among schizophrenia cases versus controls in approximately =80% of the CCS level 2 categories assessed. Common top categories of comorbidities for schizophrenia cases were mood disorders, anxiety disorders, other connective tissue disease, and diseases of the heart. Comorbidities with the highest case-control PRRs included personality disorders, suicide and intentional self-inflicted injury, and impulse control disorders. Across databases, the most commonly prescribed medications in cases were antipsychotics, antidepressants, and analgesics/antipyretics opiate agonists; the most highly prescribed antipsychotics were risperidone, quetiapine, aripiprazole, and olanzapine. This large-scale analysis quantifies the high prevalence of medical and psychiatric comorbidity burden in patients with schizophrenia, highlighting the importance of integrated medical and psychiatric care. Alkermes, Inc.