Evaluating Outcomes in Patients With Ankylosing Spondylitis Seeking Acute Care By Utilizing Elixhauser Comorbidity...

Our study aimed to review emergency department (ED) visits, hospitalizations, and discharge dispositions among United States (US) patients with ankylosing spondylitis (AS), comparing them to patients without AS using the Elixhauser Comorbidity index (ECI).

We conducted a descriptive, cross-sectional analysis of ED visits and hospitalization records from the Cerner Health Facts electronic medical record (EMR) database between 2000 and 2017. The study included 41,065 patients with AS and 28,837 matched controls. Patients with AS and patients without AS or other rheumatological disease were matched for sex, race, and age at first encounter. AS diagnoses were identified by the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) code, M45, at the time of admission or discharge, or comparable ICD-9 codes (fully listed in Supplementary Materials, Supplemental Digital Content 1, http://links.lww.com/RHU/A852). Key outcomes included the ECI, diagnoses at admission or discharge, length of stay, and discharge destination.

There were 3682 ED-only visits, 21,318 inpatient admissions, and 2224 admissions to observation among patients with a diagnosis of AS, with most cases originating from the Northeast (35%) and Southern (32%) US. Patients with AS were more likely to be admitted under inpatient or ED-only status (78% and 14%, respectively; p<0.001). Of note, there were 13,841 patients with AS identified in which visit type was unknown, and data for this was not available through Cerner Health Facts. Common diagnoses included back pain, chest pain, and abdominal pain. Patients with AS had a higher ECI (2.29; p<0.001), indicating a greater comorbidity burden, experienced longer average hospital stays (mean of 17 d; p<0.001) and were less likely to be discharged home, with more sent to hospice care or a rehabilitation facility (p<0.001).

Our study demonstrates that patients with AS experience a greater comorbidity burden, increased health care utilization seen through a greater number of admissions and longer hospitalization stays, and poorer outcomes, including fewer patients who were ultimately discharged home, and more who required rehabilitation services after acute services.