The cardiovascular risk in rheumatoid arthritis is comparable to that of diabetes, a large Danish study has shown.
Further, the risk of myocardial infarction (MI) in rheumatoid arthritis patients corresponds to that observed in the general population of individuals without the musculoskeletal condition who are, on average, 10 years older and does not appear to be affected by the duration of drug treatment for the disease, Dr. Jesper Lindhardsen of Gentofte University Hospital in Copenhagen, Denmark, and colleagues reported.
Dr. Jesper Lindhardsen
Using nationwide registers encompassing the entire Danish population older than 16 years, the investigators identified individuals with new-onset rheumatoid arthritis (RA), new onset diabetes, and new MI during a 10-year period, excluding individuals with prior disease and incomplete data entries from the full cohort of 4,311,022 subjects, they wrote.
During the 10-year study period, 9,921 individuals developed RA and 129,659 developed diabetes, the authors reported. Compared with the diabetes patients, "RA patients were more often women, used less cardioprotective medications, and had less comorbidity, whereas age was similar in the two groups," they reported.
Regarding cardiovascular outcomes, 265 of the RA patients and 3,948 of the diabetes patients had new MI, representing in both cohorts a 1.7 increased incidence rate ratio (IRR) of MI in a fully adjusted model compared with the general population in which 75,870 individuals had new myocardial infarctions, they wrote. The IRR among patients with both RA and diabetes was 2.6, "which roughly equaled the predicted additive risk for the two separate diseases, they wrote (Ann. Rheum. Dis. 2011;70:929-34).
The investigators conducted a nested case-control study that corroborated the comparable risk of MI in the RA and diabetes patients. The findings demonstrated that the increased risk in these groups was independent of treatment duration within the timeframe of the current study, they wrote.
Stratified by gender, the MI risk estimates did not differ between women and men in the RA group. In the diabetes patients, however, women were at significantly higher risk than men for the adverse cardiovascular outcome, the authors wrote. An age-dependent pattern of MI risk was also observed. Specifically, among women with RA and diabetes, respectively, the risk of MI in those younger than 50 years old was 5.5 and 5.9 times that observed in the age-matched reference group, they reported. Additionally, for women between 50 and 65 years of age, the IRRs were 1.7 and 2.6 for RA and diabetes patients, respectively.
The age-stratified patterns observed in men were different, the authors stated, noting that "the IRRs in the two oldest age groups were comparable, and even tended to be slightly higher in the 50-65 years age group of RA patients compared to the same-aged [diabetes] patients." And while the youngest men with RA had a markedly raised IRR, diabetes patients in the same age stratum had a significantly higher risk, with an IRR of 4.9 compared with 2.1, they said.
In a fully adjusted regression model in which the IRRs for MI in RA patients were calculated according to 10-year subject age intervals, "RA patients had the same, or higher, risk of MI as control subjects who were, on average, 10 years older," the authors reported.
Although the study has several limitations, including the identification of RA patients based on dispensed prescriptions and diagnosis versus the 1987 American College of Rheumatology criteria, the reliance on the use of glucose-lowering drugs as a proxy for diabetes, and the lack of information about classic cardiovascular risk factors, "the results corroborate and expand previous findings in this area of research and indicate that patients with RA should be considered for more aggressive primary [cardiovascular disease] prevention," the authors stressed.
In an accompanying editorial, Dr. Michael T. Nurmohamed and Dr. George Kitas of VU University Medical Centre in Amsterdam wrote that the findings of the current study should put to bed any doubt or debate about an enhanced cardiovascular risk in RA. "Importantly, they also provide further evidence that the cardiovascular risk in RA is broadly similar to that of contemporarily managed diabetes," they stated. The results of the study, as well as the success of cardiovascular risk management in diabetes provides a clear incentive to identify and actively manage, if necessary, cardiovascular risk in all RA patients as part of quality routine rheumatological practice" (Ann. Rheum. Dis. 2011;70:881-3).
The study was sponsored by an unrestricted grant from the Danish Rheumatism Association. The authors of the study and the accompanying editorial reported having no conflicts of interest to disclose.