Analysis of comorbidity in an emergency department using diagnostic coding: The Elixhauser Index

To analyze the comorbidity of patients attending an emergency department (ED) using the Elixhauser Index (EI) and examine its association with the length of stay and discharge destination.

We conducted aetrospective observational study based on the Emergency Department Minimum Basic Dataset for 2019, 2022, and 2023, excluding pandemic years. Diagnoses were coded using International Classification of Diseases-version-10 Clinical Modification (ICD-10-CM), and the EI was applied to assess comorbidity. Associations between comorbidity, length of stay (< 16 hours vs $ 16 hours), and discharge destination were analyzed.

More than 12% of patients had at least 1 comorbidity (EI $ 1). Among episodes < 16 hours, 92% showed no comorbidity, whereas among episodes $ 16 hours, nearly 50% had EI $ 1 (P < .001). Among patients admitted to the tertiary referral center, fewer than 7% had moderate or severe comorbidity (EI $ 2). Patients with greater comorbidity were referred to lower-complexity facilities or to hospital-at-home programs.

The EI allows characterization of the heterogeneity of the ED population. The organizational model of Hospital de la Santa Creu i Sant Pau, oriented toward geriatric and network-based care, facilitates referral of complex patients to more appropriate resources, reducing admissions to high-technology hospitals. Incorporating comorbidity analysis may improve ED planning and funding.