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Rheumatoid arthritis characteristics reflected serious infection risk
Rheumatoid arthritis characteristics and comorbidities can be used as a risk score to predict the occurrence of serious infection in patients with the disease, according to study data.
Mayo Clinic researchers investigated a population-based cohort of 584 patients (mean age, 57.5 years; 72% women) who fulfilled American College of Rheumatology criteria for rheumatoid arthritis (RA) from 1955 through 1994 and were followed up with medical records through January 2000. Researchers also evaluated 410 patients with RA (mean age, 54.9 years; 69% women), diagnosed between 1995 and 2007 and followed up through 2008, as a validation cohort. Serious infections requiring hospitalization or intravenous antibiotics were outcome measures. Multivariable Cox models were used to examine potential predictors and estimate risk scores.
Eric L. Matteson
In the original cohort, in a median follow-up of 9.9 years, 252 patients had at least one serious infection (646 total infections). Median follow-up among the validation cohort was 5.2 years and 55 patients had at least one serious infection (166 total infections). Overall rate of serious infection among the validation cohort was significantly lower compared with the original cohort (7.2 vs. 9.1 per 100 person-years) (RR=0.80; 95% CI, 0.69-0.93), reflecting a general decline in hospitalizations.
Risk score components included age, previous serious infection, corticosteroid use, elevated erythrocyte sedimentation rate, extraarticular manifestations of RA and comorbidities (coronary heart disease, heart failure, peripheral vascular disease, chronic lung disease, diabetes and alcoholism).
“It was important to see how other coexistent disease states further enhance this risk,” researcher Eric L. Matteson, MD, MPH, chair of the division of rheumatology at Mayo Clinic in Rochester, Minn., told Healio.com.
Risk score for the original cohort showed “excellent discrimination” when tested among the validation cohort (Harrell’s C statistic=0.80; 95% CI, 0.74-0.85).
“We know RA is associated with an increased risk of infection,” Matteson said. “We are as a result of this study better able to quantify this risk for patients, using readily available information from the patient’s medical history, which will be helpful in making treatment decisions regarding immune suppressive drugs, and in counseling patients about measures for infection prevention, including routine vaccinations.”
Disclosure: See the study for a full list of relevant disclosures.