Scoring Infection Risk in RA

Rheumatoid arthritis infections may be predicted by risk score

/ Author:  / Reviewed by: Robert Carlson, M.D

(RxWiki News) People with rheumatoid arthritis may have a higher risk of infection than others, but doctors have found it hard to pinpoint each patient's individual risk. Now, doctors may have a new way to rate infection risk.

Researchers found that a scoring system can predict the risk of infection in people with rheumatoid arthritis.

"Tell a doctor if  you have an infection."

If doctors know which of their arthritis patients have a higher risk of infection, they can take early steps to prevent or treat infection.

In a recent study, Eric Matteson, MD, chair of the Division of Rheumatology at Mayo Clinic, and colleagues set out to see if a risk score could be used to predict a patient's chances of developing a serious infection.

Over the course of the study, 252 of 584 rheumatoid arthritis patients (about 43 percent) had at least one serious infection. All together, those 252 patients had a total of 646 infections.

After testing the risk score on a second group of patients from the same population, the researchers found that the risk score could tell which patients had a higher risk of serious infection, with a C statistic of 8.0.

A C statistic explains how well a risk score identifies different risks between patients. The statistic changes between 0.5 and 1.0, with higher numbers showing the risk score is more effective.

The risk score in this study was calculated by looking at a number of factors, including:

  • patient history of previous serious infections
  • use of corticosteroid drugs
  • low white blood cell levels
  • erythrocyte sedimentation rate - a blood test that spots signs of inflammation
  • signs of rheumatoid arthritis in parts of the body other than the joints
  • presence of other health problems like heart disease, heart failure, diabetes, lung disease, blood vessel diseases and alcoholism

Using a risk score like the one in this study can tell doctors that their patient has a high risk of infection and may need more protections against infection, more follow-ups and changes in drug treatment, said Dr. Matteson.

One important factor that was left out of the risk score calculations was use of biologic drugs. Created in the late 1990s, biologics are used to treat arthritis patients who did not respond to methotrexate - a common treatment for rheumatoid arthritis. All biologics come with a risk of serious infection. The period of time studied by Dr. Matteson and colleagues was before the widespread use of biologics.

According to the study's authors, more research is needed to see if drug treatment can prevent infection in patients at different risk levels.

The study by Dr. Matteson and colleagues was published August 27 in Arthritis & Rheumatism, a journal of the American College of Rheumatology.

The study was funded by Genentech, the National Institute of Arthritis and Musculoskeletal and Skin Diseases and the Rochester Epidemiology Project, which is funded by a grant from the National Institute on Aging. Genentech approved the study design and reviewed and approved the study before it was submitted.

Dr. Matteson has received support from Genentech, Centocor, Pfizer, Human Genome Sciences, Novartis and UCB.

Reviewed by: 
Review Date: 
September 6, 2012
Last Updated:
July 29, 2014