For decades, researchers have suspected a connection between chronic lung diseases and rheumatoid arthritis (RA). Previous research has yielded widely varying estimates about the strength of this connection , partly because studies have used different diagnosis criteria for these diseases. Addressing this problem, Mayo researchers presented preliminary data at the American College of Rheumatology Annual Meeting on Nov. 11 confirming that patients with rheumatoid arthritis are clearly affected by chronic lung diseases.
The goal of this study is to more precisely measure the cumulative incidence of lung diseases among people with rheumatoid arthritis. Mayo researchers studied a group of 603 people who met strict American College of Rheumatology Annual Meeting diagnosis criteria for RA, examining the subjects' medical records from diagnosis through their death or last follow-up appointment.
Two pulmonologists and two rheumatologists also studied the subjects' records for evidence of chronic lung disease. Using a list of strict diagnosis criteria, individual physician's diagnoses, pulmonary function testing results, X-rays and biopsy findings, they estimated the cumulative incidence of obstructive lung disease and diffuse parenchymal infiltrative lung disease (DPILD) in the study group.
A total of 603 RA subjects were followed for a median of 14 years. The cumulative incidence of obstructive lung disease using the list of diagnosis criteria was 4.1 percent at 10 years after RA diagnosis, 9.5 percent at 20 years and 15.5 percent at 30 years. The observed incidence of DPILD using these criteria was even higher: 7.2 percent, 15.5 percent and 22.4 percent after 10, 20, and 30 years, respectively.
"Having good data that supports a link between rheumatoid arthritis and chronic lung diseases is just the first step," says Eric Matteson, M.D., Mayo rheumatologist and the study's lead researcher. "We now need additional research to explore the most effective treatment strategies for these patients and to clarify how these diagnoses impact the quality of life and incidence of mortality in these patients."