Patients who have RA and interstitial lung disease are at higher risk for dying than those who do not.
The likelihood of dying is significantly increased in patients with rheumatoid arthritis who have interstitial lung disease compared with patients who do not.
Mortality is particularly high during the first month after a combined diagnosis of rheumatoid arthritis complicated by interstitial lung disease.
Diagnostic delay may prove fatal, especially if the interstitial lung disease is already severe at presentation.
New treatments for patients with rheumatoid arthritis have caused the mortality rate to decline over the past 10 years. But even with improvements in mortality, the risk of death in patients with rheumatoid arthritis is still higher than in the general population. Most of the deaths are related to cardiovascular disease and interstitial lung disease.
Although interstitial lung abnormalities may be detected in as many as half of patients with rheumatoid arthritis before they are clinically evident, Charlotte Hyldgaard and colleagues from Denmark pointed out that the risk of progressing to clinically significant lung disease is unknown.
The authors compared mortality rates among patients who have rheumatoid arthritis and interstitial lung disease and those who have rheumatoid arthritis alone. They presented their findings in a recent Annals of the Rheumatic Diseases article.
They conducted a population cohort study that included 31,333 patients with rheumatoid arthritis. The incidence of comorbid interstitial lung disease and mortality was examined.
• Of the patients in the cohort with rheumatoid arthritis, 2.2% had interstitial lung disease.
• Patients with rheumatoid arthritis who had interstitial lung disease were more likely to be older men with seropositivity.
• A diagnosis of interstitial lung disease before rheumatoid arthritis was made in 14% of cases.
• In 34% of cases, a diagnosis of interstitial lung disease was made within 1 year of, at the same time as, or within the first year after rheumatoid arthritis diagnosis.
• Comorbidities were seen more frequently in the interstitial lung disease group. They included ischemic heart disease, congestive heart failure, and diabetes.
• One-year mortality was 13.9% In patients with rheumatoid arthritis who had interstitial lung disease (95% confidence interval [CI], 11.4% to 16.7%) and 3.8% in matched comparisons who did not (95% CI, 3.5% to 4.2%).
• Five- and 10-year mortality in patients with and without interstitial lung disease was 39.0% vs 18.2% and 60.1% vs 34.5%, respectively.
• Hazard ratio rates were higher for patients who had a diagnosis of rheumatoid arthritis before interstitial lung disease.
• The hazard ratio rate for mortality within 30 days of interstitial lung disease diagnosis was 10.4 (95% CI, 5.9%-18.2%).
Implications for physicians
• Patients who have rheumatoid arthritis and interstitial lung disease are at higher risk for dying than those who do not.
• Physicians should strive to make a diagnosis as quickly as possible because the risk of death is more prominent in the short term after diagnosis, possibly as a result of delays in diagnosis.
• Seropositivity does not appear to facilitate stratification of risk in patients with interstitial lung disease and rheumatoid arthritis.
This study was supported by a grant from the Danish Rheumatism Association and by the Program for Clinical Research Infrastructure.
Hyldgaard C, Hilberg O, Pedersen AB, et al. “A population-based cohort study of rheumatoid arthritis-associated interstitial lung disease: comorbidity and mortality.” Ann Rheum Dis. 2017;76:1700-1706. doi: 10.1136/annrheumdis-2017-211138. Epub 2017 Jun 13.