Background/Purpose: Rheumatoid arthritis (RA) is
associated with increased risk of cardiac mortality. With better treatment
modalities, some studies suggest that infarction (AMI) mortality in RA has decreased.
We aimed to evaluate temporal trends of incidence and mortality of RA in AMI
hospitalizations in a nationally representative sample.

Methods: We reviewed Nationwide Inpatient
Sample (NIS) data over 10 year period from 2002-2011 for adult AMI hospitalizations
as a primary diagnosis with RA as secondary diagnosis using validated ICD9-CM
codes. We calculated unadjusted proportions of mortality yearly and used survey
logistic regression to calculate adjusted odds ratios (aOR)
for hospital mortality and adverse discharge and after stratifying for age (≤50
vs. >50).

Results: We identified a total of 6588743 AMI hospitalizations from 2002-2011 of which 77040 (1.16%) had a
diagnosis for RA. The proportion of patients with RA in AMI hospitalizations
increased from 0.96% in 2002 to 1.44% in 2011.  RA hospitalizations were older
(70.4 vs. 67.7 years; p<0.01); more female (62.7% vs. 40%; p<0.01); with
a higher proportion of whites (82.3% vs. 77.7%; p<0.01) and a higher Charlson comorbidity index (2 vs. 1.5; p<0.01). The
unadjusted mortality rates in RA hospitalizations yearly were similar to
hospitalizations without RA. (Figure 1) After adjusting for age, gender, race, Charlson comorbidity index, hospital level characteristics,
cardiac procedures, RA hospitalizations had lower odds-ratio for hospital
mortality (aOR=0.76; 95% CI= 0.70-0.83; p<0.01)
compared to non-RA hospitalizations. However, in hospitalizations ≤50
years, there was no significant difference in the adjusted odds of hospital
mortality (aOR=0.68; 95% CI 0.38-1.21; p=0.19) or
adverse discharge (adjusted aOR=1.03; 95% CI
0.84-1.28; p=0.73)

Conclusion:  The odds of hospital mortality
in RA hospitalizations with AMI are lower than non-RA hospitalizations. This is
likely related to better disease recognition and risk modification in RA
patients. However, the mortality in RA hospitalizations younger than 50 years
was similar to non-RA hospitalizations, suggesting an unmet need for better
disease and comorbidity management in younger RA patients.

Figure 1.  Proportion of Mortality in AMI
Hospitalizations Stratified by Rheumatoid Arthritis Status