The risk of myocardial infarction in rheumatoid arthritis and diabetes mellitus: a Danish nationwide cohort study.
Level 3 - non-randomized controlled study
Nationwide observational cohort study using administrative registry linkage.
PubMed 21389043 · doi:10.1136/ard.2010.143396
What was done
A nationwide Danish register-based cohort study followed the entire Danish population (4,311,022 individuals) from January 1, 1997 to December 31, 2006. Linkage of administrative registries identified patients who developed rheumatoid arthritis (RA) or diabetes mellitus (DM). Multivariable Poisson regression models assessed the incidence rate ratio (IRR) of myocardial infarction (MI), adjusting for cardioprotective medications, comorbidity, and socioeconomic status.
What was found
During follow-up, 10,477 individuals developed RA and 130,215 developed DM. The overall IRR of MI was 1.7 (95% CI 1.5 to 1.9) in patients with RA, identical to the risk in patients with DM (IRR 1.7, 95% CI 1.6 to 1.8; p = 0.64 for difference). Relative risk was elevated across all age and sex strata and was highest in younger individuals, reaching an approximate sixfold increase in women younger than 50 years with either condition. The RA-associated risk of MI was not modified by duration of pharmacological RA treatment and was equivalent to the MI risk of non-RA individuals who were approximately 10 years older.
Why it matters
This study demonstrates that rheumatoid arthritis confers a cardiovascular risk comparable in magnitude to diabetes mellitus, supporting aggressive cardiovascular risk assessment and prevention strategies in patients with RA.
Limits
The study relied on administrative diagnostic codes and prescription registries, which lack granular clinical details such as smoking status, body mass index, blood pressure, lipid levels, and disease activity markers. The cohort was limited to the Danish population, which may restrict generalizability to more diverse populations.
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