Background: Acute coronary syndrome describes various conditions related to sudden, reduced blood flow to the heart. Some traditional risk factors for ACS include older age, diabetes (DM), hypertension (HTN), hyperlipidemia (HLD), smoking, and obesity. Rheumatoid arthritis (RA) is an autoimmune disease which is a novel risk factor for ACS. Therefore, to better understand the impact of this disease, we investigated whether RA is associated with increased mortality, readmission, and length of stay (LOS) in patients with ACS alongside traditional risk factors.

Methods: 33,223 patients who were admitted with ACS to the West Florida division of a large health system from 1/1/2016 to 12/31/2023 were retrospectively included in the study. The association of risk factors, including RA, age, sex, Black ethnicity, other non-Caucasian ethnicities, current tobacco use, former tobacco use, alcohol use disorder, body mass index (BMI), HLD, and DM, with in-hospital mortality and 30-day readmission was evaluated via logistic regression and with LOS via negative binomial regression.

Results:

• For RA: The odds of in-hospital mortality was 0.779 times as likely (p-value .2252) and the odds of 30-day readmission was 0.948 times as likely (p-value .5671). RA resulted in a 1.034 factor increase in LOS (p-value .3369).
• For traditional risk factors: The odds of in-hospital mortality were 1.071 times as likely for every 1-year increase in age (p-value <.0001), 1.285 times as likely for current smokers (p-value 0.0020), 0.970 times as likely for every 1-point increase in BMI (p-value <.0001), 0.647 times as likely for patients with HLD (p-value <.0001), and 1.349 times as likely for patients with DM (p-value <.0001). Age, DM, and alcohol use disorder resulted in statistically significant increased 30-day readmission. Age, male sex, Black ethnicity, other non-Caucasian ethnicities, former tobacco use, current tobacco use, DM, and alcohol use disorder resulted in statistically significant increased LOS.

Conclusion: In terms of the discrete odds and incident rate ratios, RA was surprisingly associated with decreased in-hospital mortality and 30-day readmission in the setting of ACS despite an associated increased LOS. In terms of statistical significance, there was no difference in these outcomes in patients with RA versus patients without RA. Meanwhile, the traditional risk factors continued to show worse outcomes with statistical significance in the same patient population. Knowledge of this may prevent over-utilization of time, equipment, and resources when addressing hospitalized patients with RA presenting with ACS.