Background/Purpose: Patients with the autoimmune rheumatic disease have an increased risk of acute myocardial infarction (MI). Our study was designed to compare the prevalence, characteristics and in-hospital outcomes among patients with Rheumatoid Arthritis (RA), Systemic lupus erythematosus (SLE), Systemic Sclerosis (SSc), Gout and Osteoarthritis (OA), who developed acute myocardial infarction during 2002- 2018 in a national cohort of US hospitalizations.

Methods: We used the National Inpatient Sample (NIS) database to identify hospitalizations of patients with MI and autoimmune rheumatic diseases including RA, SLE, SSc, Gout. We compared the baseline characteristics, comorbidities, and age-adjusted mortality of patients among the study groups; OA hospitalizations with MI served as a control population. Comparisons of continuous and discrete data were made with ANOVA and the Rao-Schitt chi-square test, respectively. All analyses utilized SAS 9.4 and incorporated the NIS sampling design.

Results: Between 2002- 2018, there was a total of 844,427 MI hospitalizations with RA, SLE, SSc, Gout, and OA (RA: 87,637, SLE: 25,067, SSc: 5,523, Gout: 197,845, and OA: 528,355). Several differences were observed; females were disproportionately higher in SLE, SSc, and RA groups compared to OA (80.6%, 80.3%, 62.6% vs 55%). There was no statistically significant difference in Charlson Comorbidity Index for readmission and mortality among the groups studied. Patients with SLE (60 years; 95% CI: 50 years to 70 years) and SSc (67 years; 95% CI: 58 years to 76 years) had an early age of admission for inpatient hospitalization in comparison to OA (76 years; 95% CI: 66 years to 80 years). The average age of morality is lower in patients with SLE (66 years; 95% CI: 56 years to 76 years) and SSc (72 years; 95% CI: 60 years to 79 years) compared to OA (83 years; 95% CI: 76 years to 89 years). Refer to Table 1 for full characteristics as described above. Inpatient mortality was higher in those admitted with SSc, RA, and SLE in comparison to OA (10.2%, 5.4%, 5.2% vs 4.6%) (Table 2). However, Gout had decreased inpatient mortality compared to OA (4.3% vs 4.6 %) (Table 2).

Conclusion: This is the most updated NIS study comparing the clinical baseline hospitalization characteristics of patients with four autoimmune rheumatic diseases with acute myocardial infarction. Acute MI in SLE and SSc develop at an earlier age compared to other groups. We also observed increased mortality in patients with SSc compared with RA/ SLE/ Gout or OA. There is not much literature on outcomes of MI in patients with SSC and our study demonstrates that this patient group is an independent risk for in-hospital mortality. Therefore, further studies need to be done to evaluate the causes of higher mortality in this group.

Table 1. Clinical characteristics of hospitalized patients with four different systemic rheumatic diseases with myocardial infarction and Osteoarthritis patients with myocardial infarction

Table 2: Hospital outcomes comparing four different systemic rheumatic diseases and osteoarthritis patients with myocardial infarction.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/characteristics-and-outcomes-of-myocardial-infarction-in-patients-with-rheumatoid-arthritis-systemic-lupus-erythematosus-systemic-sclerosis-gout-and-osteoarthritis-patients-using-the-national-inpat/