COPENHAGEN — The increased risk for myocardial infarction in patients with rheumatoid arthritis starts to become apparent a year after rheumatoid arthritis is first diagnosed, based on a case-control study with more than 45,000 people.
“The increased risk of myocardial infarction is evident earlier in the course of rheumatoid arthritis than previously thought,” Marie Gunnarsson said at the annual European Congress of Rheumatology. “The finding underscores the need for early heart-disease prevention measures in this population,” added Ms. Gunnarsson, an epidemiology researcher in the Institute of Environmental Medicine at the Karolinska Institute in Stockholm.
The spike in MI risk occurs precipitously with RA diagnosis. In a prior report, Ms. Gunnarsson and her associates showed no excess risk for MI exists when RA is first diagnosed.
The study included 7,653 patients diagnosed with RA during 1996-January 2007 and entered into the Swedish RA register. Each of these patients was newly diagnosed, within 18 months from when RA symptoms first appeared. Each patient was matched by gender, age, and residential area with five people from the general Swedish population. The average age of the RA patients and matched comparators was 57 years, and 71% were women.
During an average follow-up of almost 5 years in both groups, patients with RA faced a 70% increased risk for being hospitalized for an acute MI during the second through fourth year following their RA diagnosis, compared with controls, a statistically significant difference, Ms. Gunnarsson reported.
Hospitalizations for MI also were 70% higher among patients with RA during years 5-10 following their diagnosis. (See box.) In contrast, during the first year following RA diagnosis the patients also had an increased rate of MI hospitalizations, compared with controls, but the difference was not statistically significant.
The analysis showed no significant differences in the rates of MI death between the RA patients and controls during any follow-up period. The rate of death from any cause was also not significantly different between the two groups during most follow-up periods. The exception was during the period 5-10 years following RA diagnosis, when the RA patients had a 10% increased rate compared with the controls, a difference on the cusp of statistical significance.
Another analysis looked at the interaction of rheumatoid factor and MI hospitalizations. RA patients positive for rheumatoid factor had a slightly higher hospitalization rate than all RA patients, peaking with a rate twice the control rate at 5-10 years following RA diagnosis.
The study was funded in part by Astra Zeneca. Ms. Gunnarsson and her colleagues had no other disclosures to report.
Patients with RA faced a 70% increased risk for being hospitalized for an acute MI.
Source MS. GUNNARSSON
Source ELSEVIER GLOBAL MEDICAL NEWS