A new study lends insights into the prevalence of lung abnormalities in patients with newly diagnosed cases of rheumatoid arthritis (RA).
A high percentage of patients with early rheumatoid arthritis (RA) have abnormal findings on high-resolution CT (HRCT) examination, according to new study findings, suggesting lung involvement remains undiagnosed in many patients.
These and other findings were recently published in Advances in Rheumatology.
The authors explained that about 30% of patients with RA are believed to have lung involvement, the most serious form of which is interstitial lung disease (ILD). Patients with RA and ILD have 3 times the mortality rate, they said.
It is believed that airway involvement is even more common, although the investigators said most of the available evidence is based on the study of established patients, with little existing data available to quantify the prevalence in patients with a new diagnosis.
The investigators sought to add to the record by examining lung involvement in patients who were less than 2 years from initial RA diagnosis. They designed a multicenter study that included a structured questionnaire, HRCT, physical exam, and lung functional tests.
Eighty-three patients were recruited, 83% of whom were female. The patients had a median time since diagnosis of 3 months.
Seventy-two percent of patients had compromised airways and 7.5% of patients had interstitial abnormalities. The authors noted that about 50% of the patients in the study had previously or currently smoked, which may have been related to the high rate of airway compromise.
“However, this finding is consistent with studies showing the presence of RA-associated antibodies evidencing an underlying autoimmune phenomenon before the appearance of clinical manifestations, in some cases several years (10 or 15) before,” they wrote, adding that an analysis of their data did not show an association between smoking status and the presence of lung compromise in HRCT.
Lung functional tests showed that the most common alteration was reduced diffusing capacity of the lung for carbon monoxide (DLCO), which was reported in 14% of patients.
Patients with at least 1 abnormality identified during the physical exam were more likely to have lung involvement on HRCT. These patients also had significantly lower forced value capacity and DLCO scores and higher residual volume to total lung capacity values.
No connection between joint involvement and HRCT abnormalities was found.
“Our [study] suggests that early lung screening with HRCT and lung functional tests can detect incipient alterations in a large number of patients,” the authors wrote. “This represents an opportunity to start early treatment when indicated.”
The authors noted a number of limitations to their study. Their sample size was relatively small, they said, and the study included patients with a history of smoking, which potentially confounded the results.
“Finally, the study has a cross-sectional design that does not allow us to arrive [at] conclusions regarding causality,” they added.
Still, they said the data suggest early lung screening of patients with RA may be useful, particularly if the findings are verified by larger studies.
Paulin F, Secco A, Benavidez F, et al. Lung involvement prevalence in patients with early rheumatoid arthritis without known pulmonary disease: a multicentric cross sectional study. Adv Rheumatol. Published online August 24, 2021. doi:10.1186/s42358-021-00209-0