Rheumatoid Arthritis Diagnosis the Biggest Factor in Increased MI Risk

Barbara Boughton

October 28, 2008

October 28, 2008 (San Francisco, California) — The diagnosis of rheumatoid arthritis is the most influential factor in the increased incidence of myocardial infarction (MI) seen in RA patients, according two population-based studies presented here at the American College of Rheumatology 2008 Annual Meeting.

Yet traditional risk factors such as age, sex, hypertension, diabetes, and smoking are also important in determining risk for MI, and of these, modifiable risk factors should be aggressively treated, said Christopher Edwards, MD, consultant rheumatologist and honorary senior lecturer in the department of rheumatology at Southampton General Hospital in Southhampton, UK and lead investigator on both studies.

While medications such as DMARDs have previously been linked to MI risk, the studies presented here found no such correlation. However, the researchers did find that treatment with lipid-lowering drugs produced a significant reduction in MI incidence, although antihypertensives had no effect.

“As a clinician I want to know what’s driving the increase in MI incidence in RA patients. Not only do RA patients have an increased rate of MI, but the MIs are silent with an increased case fatality, and [occur] earlier in life. Not only do RA patients suffer from MI, but it’s bad MI,” Dr. Edwards told meeting attendees.

“Previous studies have looked at traditional risk factors in RA as causative factors for heart attack, but they are not the whole story,” he added.

To assess the incidence of MI, as well as the factors contributing to it, the UK researchers analyzed the United Kingdom General Practice Research Database (GPRD), which contains the medical records of over seven million individuals. The investigators were able to identify 34,364 adults with RA and 103,089 age and sex-matched controls, studied between 1987 and 2002. They found that RA patients suffered MI at a rate of 6.49 per 1000 people per year versus 2.96 in the control group.

Although the database contained data from 600 medical practices and 5% of the UK population, it also had its limitations, the researchers acknowledged. Some diagnostic information on patients — such as lipid levels, hypertension, and smoking status — was missing from the GPRD, and other information such as exposure to DMARDs and hypertension and lipid-lowering medications was not complete.

Yet in their analysis, the researchers found that having a diagnosis of RA was the strongest influence on MI risk. A diagnosis of RA increased the incident rate ratio (IRR) for MI (2.23; 95% confidence interval [CI], 2.07 - 2.41; P < .001), and this effect remained even when the researchers controlled for traditional risk factors, antihypertensive drugs, lipid-lowering drugs, and DMARDs/prednisolone use. Of the traditional risk factors, body mass index (BMI) alone did not produce a significant effect on MI. The researchers also found that treatment with lipid-lowering drugs produced a significant decrease in MI incidence (IRR, 0.75; 95% CI, 0.62 - 0.90; P = .003), although antihypertensives had no effect (IRR, 0.92; 95% CI, 0.84 - 1.00; P = .062).

In a related study by the same researchers, they analyzed the effect of DMARDs and prednisolone use on MI incidence. In the patients who had suffered an MI, 73% had taken a DMARD or prednisolone prior to the study, and in 56% of cases, patients had taken these drugs in the 2 months prior to the MI. The researchers’ data analysis showed that DMARDs were protective against MI, but prednisolone increased MI risk. However, when adjusted for confounders (such as BMI, hypertension, diabetes, and smoking), the effects of these drugs were no longer significant.

“This study shows us just one piece of the jigsaw puzzle unfolding, and helps us decide how much investment we should make in treating RA and traditional risk factors,” Dr. Edwards told the attendees.

“In my opinion it’s important to treat RA because it’s the biggest risk factor for MI, but we can’t forget the traditional risk factors either,” he told Medscape Rheumatology. “We need to give these approaches equal weight.”

Deborah Symmons, MD, professor of rheumatology at Manchester University in the United Kingdom and the moderator of the session, agreed. “The implications of these studies are that we have to target traditional risk factors as aggressively as we can and at the same time we have to manage the disease activity of RA,” she said.

The studies did not receive commercial support. Dr. Edwards and Dr. Symmons have disclosed no relevant financial relationships.

American College of Rheumatology (ACR) 2008 Annual Scientific Meeting: Abstract 688. Presented October 26, 2008.


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