Cardiovascular Risk in RA
Many studies have demonstrated that people with rheumatoid arthritis (RA) have a higher risk of cardiovascular disease than people who don’t have RA. Relatively little is known, however, about how age and prior cardiovascular status affect that risk.
What problem was studied?
Arthritis Foundation-funded researcher Daniel H. Solomon, MD, MPH, and others at Brigham and Women’s Hospital in Boston sought to analyze the distribution of cardiovascular events in a large population of people with RA. Rates of myocardial infarction (heart attack), stroke and death due to cardiovascular disease were examined among a large cohort.
What was done in the study?
The total study population consisted of all people over the age of 18 residing in British Columbia who used its publicly funded health-care system. Researchers examined health-care data from 1999 through 2003. A person was defined as having RA if they had at least three RA-related physician visits during a two-year period. The study period began at the time of the third RA-related visit (the index date) and continued until the patient experienced a cardiovascular event, left British Columbia or died. For each person with RA, 10 people matched for age, sex and index date (but who did not have RA) were selected from the total study population as the comparator group.
The health records of the people with RA and the comparator group were reviewed for myocardial infarctions, ischemic stroke and death from cardiovascular disease. To determine the effect of a prior cardiovascular event on the risk of having a future cardiovascular event, the researchers looked back two years before the index date to find any pertinent events.
What were the study results?
In total, 25,385 people with RA were identified, with more than 70,000 person-years of follow-up data. People with RA had approximately twice the risk of myocardial infarction and stroke compared with people without RA. They also had a 30% increased risk of cardiovascular death and a heightened risk of 30-day mortality after a cardiovascular event.
Rates were calculated according to age category. Although people with RA had higher risk rates across all age groups, the rate ratio was highest for the youngest age group (18–49 years). The absolute difference in cardiovascular event rates was much higher among patients with RA in the older categories compared with the younger categories (see sidebar). This means that older people with RA were the most likely to sustain a cardiovascular event of some kind (absolute risk), but that people with RA in the youngest category had the proportionately highest risk compared with young people without RA (relative risk).
Next, the team evaluated the pattern of risk among subjects who did or did not have prior cardiovascular events. Here they found that people with RA who had a previous event had a lower risk of experiencing a cardiovascular event during the study period than those without RA who had a prior cardiovascular event. This result was unexpected and the reasoning behind the apparent protective effect is not known.
What does this mean for people with RA?
The group in this study of more than 25,000 RA patients with the highest absolute risk of sustaining a cardiovascular event was older patients with RA. The groups with the highest relative risk were younger RA patients and those RA patients without known cardiovascular disease. Therefore, both young and old RA patients should be included in cardiovascular preventive strategies.
Solomon DH, Goodson NJ, Katz JN, et al. Patterns of cardiovascular risk in rheumatoid arthritis. Ann Rheum Dis. Published online June 2006.