NEW YORK (Reuters Health) Mar 10 - Patients with rheumatoid arthritis are at increased risk for interstitial lung disease, which significantly impacts their survival, researchers report in the February 12th online issue of Arthritis and Rheumatism.
No population-based studies have investigated the full spectrum of patients with rheumatoid arthritis for the presence of interstitial lung disease and compared the incidence between those with and without rheumatoid arthritis.
Dr. Tim Bongartz and colleagues from Mayo Clinic College of Medicine, Rochester, Minnesota, assessed the incidence, predictors, and mortality of interstitial lung disease in 582 patients with rheumatoid arthritis and 603 subjects without rheumatoid arthritis who were followed for a mean of 16.4 and 19.3 years, respectively. The mean age at disease onset was 58 years.
The 30-year cumulative incidence of interstitial lung disease was 7.7% for rheumatoid arthritis patients and 0.9% for controls. Patients with rheumatoid arthritis had a significantly higher risk of interstitial lung disease than those without rheumatoid arthritis (HR, 8.96).
The risk of interstitial lung disease increased with age at rheumatoid arthritis onset (HR per 10 year increase in age: 1.41) and was higher in males (HR, 4.37). The risk was also increased with more severe rheumatoid arthritis.
Among patients with rheumatoid arthritis, the median survival after a diagnosis of interstitial lung disease was 2.6 years -- significantly lower than the expected median survival of 9.9 years for rheumatoid arthritis patients overall (p < 0.001).
"When removing the effect of interstitial lung disease on patient survival, the cumulative mortality of patients with rheumatoid arthritis dropped by 2.1%," the researchers said. "Thus, the excess deaths in rheumatoid arthritis would be reduced by 13%, if the risk of interstitial lung disease in rheumatoid arthritis was the same as in non-rheumatoid arthritis subjects."
Arthritis Rheum 2010.