Source: John Wiley & Sons, Inc. Mayo Clinic study indicates rheumatoid arthritis as an independent risk factor for heart failure
A serious chronic disease, rheumatoid arthritis (RA) is characterized by inflammation and damage of the joint, major organ involvement and increased mortality. Among patients, about one in three deaths results from cardiovascular disease (conditions affecting the heart or blood vessels). Congestive heart failure (CHF) is a major contributor to cardiovascular-related deaths – but not just among RA patients.
This condition progressively weakens the heart's pumping power, leading to retention of fluid that causes swelling of legs and abdomen, as well as congestion in the lungs. A leading cause of hospitalization among senior citizens, CHF affects up to 5 percent of Americans over age 65. Its victims have anywhere between a 4- and 18-fold increased risk of dying from a cardiovascular event.
In the general population, studies have associated CHF with cytokines. Cytokines are molecules the body produces to regulate inflammation. Cytokines are also important in autoimmune diseases, including RA. On the strength of this link, researchers at the Mayo Clinic set out to investigate whether RA patients are more vulnerable to this form of heart disease.
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Published in the February 2005 issue of Arthritis & Rheumatism (http://www.interscience.wiley.com/journal/arthritis), their findings indicate RA as a significant risk factor for CHF – independent of established risk factors for heart attack and a history of atherosclerosis. Indeed, based on their study of over 1,100 subjects over 46 years, the researchers concluded that the odds for developing CHF are doubled among RA patients.
The study's subjects were all residents of Olmsted County in Rochester, Minnesota. Using a county-wide medical records linkage system, the researchers identified 575 patients with RA, diagnosed between January 1, 1955 and January 1, 1995. These patients were further classified as rheumatoid factor (RF) positive or negative. From the same patient database, the researchers also randomly selected 583 individuals without RA. For each patient with RA, an individual without RA was matched for birth year, gender, and length of medical history. The majority of the subjects were white and female. The median age at baseline, the year of RA diagnosis, was 57.
Working with a team of cardiologists, rheumatologists, and nurses, the researchers reviewed the medical records of every study participant, with attention to personal and family history of hypertension, high cholesterol, diabetes, and atherosclerotic heart disease, including heart attacks and angina. They also examined data collected on cigarette smoking status, body mass index, and other established risk factors for heart disease.
For the foundation of their analysis and comparison, the researchers had access to a median of 26 years of complete medical history before baseline, plus a median of 15 years of follow-up. During the follow-up period, a total of 165 patients with RA and 115 individuals without RA had a confirmed diagnosis of CHF. After adjusting for cardiovascular-related risk factors and any occurrence of atherosclerotic heart disease, past or present, researchers found that RA patients had twice the risk for CHF compared with the control subjects. This finding remained consistent for all ages, in both sexes, and consistently throughout the duration of RA disease. Among RA patients, the risk was higher in those who were RF positive.
As researcher Paulo Nicola, M.D., notes, this study not only provides evidence for RA as a significant independent risk factor for heart failure but also lends support to the role of systemic inflammation in the development and prognosis of CHF. "Physicians who care for patients with RA should be aware of the increased risk of CHF in these patients," Dr. Nicola stresses. "This increased risk may be present at the earliest stages of the disease and may occur in the absence of overt cardiovascular risk factors or heart disease. Further research should address characteristics that predict CHF incidence, severity, and survival in these patients, as well as determine the role of RA therapy."
This study's senior investigator is Sherine Gabriel, M.D., M.Sc., Mayo Clinic rheumatologist, epidemiologist and chair of the Department of Health Sciences Research. Other investigators include: Hilal Maradit-Kremers, M.D.; Veronique Roger, M.D., Steven Jacobsen, M.D., Ph.D.; Cynthia Crowson; and Karla Ballman, Ph.D. Article: "The Risk of Congestive Heart Failure in Rheumatoid Arthritis: A Population-Based Study Over 46 Years," Paulo Jorge Nicola, Hilal Maradit-Kremers, Veronique Lee Roger, Steven James Jacobsen, Cynthia Sue Crowson, Karla Veronica Ballman, and Sherine Emily Gabriel, Arthritis & Rheumatism, February 2005; 52:2; pp. 412-420.