Individuals with both physical and mental health problems may have elevated levels of emergency department (ED) service utilization either for index conditions or for associated comorbidities. This study examines the use of ED services by Medicaid beneficiaries with comorbid diabetes and schizophrenia, a dyad with particularly high levels of clinical complexity.

Retrospective cohort analysis of claims data for Medicaid beneficiaries with both schizophrenia and diabetes from fourteen Southern states was compared with patients with diabetes only, schizophrenia only, and patients with any diagnosis other than schizophrenia and diabetes. Key outcome variables for individuals with comorbid schizophrenia and diabetes were ED visits for diabetes, mental health-related conditions, and other causes.

Medicaid patients with comorbid diabetes and schizophrenia had an average number of 7.5 ED visits per year, compared to the sample Medicaid population with neither diabetes nor schizophrenia (1.9 ED visits per year), diabetes only (4.7 ED visits per year), and schizophrenia only (5.3 ED visits per year). Greater numbers of comorbidities (over and above diabetes and schizophrenia) were associated with substantial increases in diabetes-related, mental health-related and all-cause ED visits. Most ED visits in all patients, but especially in patients with more comorbidities, were for causes other than diabetes or mental health-related conditions.

Most ED utilization by individuals with diabetes and schizophrenia is for increasing numbers of comorbidities rather than the index conditions. Improving care in this population will require management of both index conditions as well as comorbid ones.