The increased heart disease risk may be present even before the diagnosis of rheumatoid arthritis, according to the researchers. During the two years before diagnosis of rheumatoid arthritis, patients with this disease were three times more likely to have been hospitalized for an acute heart attack and five times more likely to have an unrecognized heart attack. They were also less likely to have had a history of chest pain, compared to those without rheumatoid arthritis. After their diagnosis, the rheumatoid arthritis patients were twice as likely to experience unrecognized heart attacks and sudden cardiac deaths.
Hilal Maradit Kremers, M.D., lead study investigator and research associate in the Mayo Clinic Department of Health Sciences Research, says the study suggests three major messages for rheumatoid arthritis patients:
The researchers were surprised to find that the increased cardiac events in rheumatoid arthritis patients could not be explained by an increase in traditional heart disease risk factors such as elevated cholesterol, blood pressure and body mass index, diabetes, and alcohol abuse, indicates Dr. Maradit Kremers.
"What we are finding is that though traditional cardiovascular risk factors are important, they are less important for those with rheumatoid arthritis," says Dr. Maradit Kremers. "Something else is going on. It could be that rheumatoid arthritis and heart disease have a common origin. What we do know is that the cause cannot be explained by just one factor. It is multifactorial."
To date, there also is no definitive information for rheumatoid arthritis patients about steps they can take to avoid heart disease, according to the Mayo Clinic researchers. Meanwhile, they indicate that it is critical that rheumatoid arthritis patients recognize their risks for heart disease and that they seek medical care for any cardiac symptoms or complaints.
Dr. Maradit Kremers explains that the silent heart attacks found in the study usually were detected when the rheumatoid arthritis patient saw a physician for some other reason and an electrocardiogram was ordered, revealing a past heart attack. "It's possible that people suffering from rheumatoid arthritis have so much pain in their joints and are receiving so many painkillers that they either don't feel the chest pain in the same way as those without rheumatoid arthritis or don't appreciate its importance," she says.
Previous research has shown rheumatoid arthritis patients have a higher risk of early death than others and that these deaths are mostly due to cardiovascular disease. The Mayo Clinic research team conducted this study to discover exactly why.
"We suspect that the systemic inflammation that characterizes rheumatoid arthritis also promotes cardiovascular disease and cardiovascular death," says Sherine Gabriel, M.D., the study's senior author and Mayo Clinic rheumatologist, epidemiologist and chair of the Department of Health Sciences Research. "And the goal of our research is to disentangle the complex relationships between these two diseases."
For this study, Mayo Clinic researchers studied a group of 603 Rochester residents diagnosed with rheumatoid arthritis between Jan. 1, 1955 and Jan. 1, 1995 and compared them with 603 Rochester residents of the same ages and gender without rheumatoid arthritis. Both the patients and the comparison subjects were followed up for a median of 26 years before rheumatoid arthritis diagnosis and 15 years after diagnosis. The researchers collected detailed information about all study subjects' cardiac events and their traditional cardiovascular risk factors: diabetes, blood pressure, cholesterol, body mass index and smoking.
The paper detailing these findings is entitled "Increased Unrecognized Coronary Heart Disease and Sudden Deaths in Rheumatoid Arthritis: A Population-Based Cohort Study."
Note for reporters: As the subjects in which the present analysis was conducted 1) have no direct patient relationship with the investigators and 2) participated in this study under strict confidentiality agreements, the participants are not available for news media interviews. The lead investigator, Dr. Gabriel, is available to speak to news media.
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