Asthma and chronic obstructive pulmonary disease were both linked to an increased risk of rheumatoid arthritis in a recent large, prospective cohort study, researchers have reported, which adds to a growing body of evidence that airway inflammation is implicated in the development of this disease.
Dr. Jeffrey A. Sparks
RA risk was increased by about 50% among asthma patients, even when excluding those who had ever smoked, according to the study’s results, which were based on more than 200,000 women in the Nurses’ Health Study I and II.
Risk of RA nearly doubled among those with chronic obstructive pulmonary disease (COPD), with an even stronger association seen in older ever-smokers, according to authors of the study.
The findings not only strengthen the case for the potential role of obstructive lung diseases in RA development, according to the study’s authors, but also suggest that health care providers need to lower the bar for evaluation of patients with lung diseases and inflammatory joint symptoms.
“If these patients develop arthralgias, then the clinicians taking care of them should have a low threshold to consider RA, and perhaps refer, or check these patients with a diagnostic test for RA,” said researcher Jeffrey A. Sparks, MD, of Brigham and Women’s Hospital and Harvard Medical School in Boston.
What’s perhaps not as clear now is whether screening obstructive lung disease patients in the absence of early RA signs would be warranted: “I don’t know if we’re quite at the point where we would need to screen these patients if they’re not symptomatic,” Dr. Sparks said in an interview.
The study by Dr. Sparks and colleagues is, by far, not the first study to implicate asthma or other lung conditions in RA development. However, most previous studies are retrospective, and interpretation of the findings has been subject to limitations such as inadequate power to detect an increased risk or lack of adjustment for important confounding factors, such as smoking.
As such, the study by Dr. Sparks and colleagues is believed to be the first-ever prospective study to evaluate asthma and COPD as risk factors for RA, study authors reported in Arthritis & Rheumatology.
Researchers were able to identify 1,060 incident RA cases that developed in 15,148 women with asthma and 3,573 with COPD in the study with more than 4 million person-years of follow-up.
The association between asthma and increased RA risk was seen not only for the asthma population as a whole (hazard ratio, 1.53; 95% confidence interval, 1.24-1.88), but also for the subset of women who had never smoked, to a similar degree (HR, 1.53; 95% CI, 1.14-2.05), the report shows.
COPD’s association with RA risk was apparent overall (HR, 1.89; 95% CI, 1.31-2.75) and even more so in the subgroup of ever-smokers 55 years of age and older (HR, 2.20; 95% CI, 1.38-3.51), the data further show.
Dr. Kevin D. Deane
Findings of studies looking at the inflammation of airways and other mucosal sites are “critically important to understand” when it comes to trying to prevent RA, said Kevin Deane, MD, of the University of Colorado at Denver at Aurora.
“If we indeed are trying to prevent rheumatoid arthritis in terms of the joint disease, we may need to look at these mucosal sites in individuals who don’t yet have joint disease as potential sites to target for prevention, or at least areas to study to understand how prevention may work,” said Dr. Deane, principal investigator on the National Institutes of Health–funded Strategy for the Prevention of RA (StopRA) trial.
With that in mind, it’s conceivable targeting a lung process might prevent joint disease in a patient with asthma or airway inflammation and blood markers that indicate a risk of RA, Dr. Deane said in an interview.
Blood markers of RA have been evaluated in some recent studies, with findings that provide further evidence of a link between lung diseases and RA, and vice versa.
In particular, anti–citrullinated protein antibodies (ACPA) are clearly central to RA pathogenesis. And while asthma is increasingly linked to RA risk, there have been relatively little data on any potential links between ACPA and asthma.
That research gap led to a case-control study of the Nurses’ Health Study I and II (on which Dr. Sparks was senior author) showing that asthma was strongly linked to elevated ACPA in blood drawn from patients prior to a diagnosis of RA.
Results, published last year in Arthritis Research & Therapy, showed a significant association between asthma and pre-RA ACPA elevation (odds ratio, 3.57; 95% CI, 1.58-8.04), after adjustment for smoking and other potentially confounding factors. Investigators said the findings provided evidence that chronic mucosal airway inflammation is a factor in the development of ACPA and in the pathogenesis of RA.
In a follow-up study published more recently in Arthritis Care & Research, investigators showed that, among women in the Nurses Health Study I and II, pre-RA ACPA elevation was linked to increased risk of COPD, compared with controls (HR, 3.04; 95% CI, 1.33-7.00), while the risk for development of asthma was similar in women with or without elevated pre-RA ACPA.
That study was in part an attempt to establish a “timeline” related to antibodies, lung diseases, and RA onset, Dr. Sparks said in the interview.
“We think that probably the asthma is more important in developing the antibody, but that once you have the antibody, if you didn’t have asthma by then, you’re unlikely to develop it,” he said. “So asthma seems to be something that could happen before the antibody production, whereas COPD seems to happen after – but ACPA seems to be the common link in both of these obstructive lung diseases.”
The study in Arthritis & Rheumatology linking asthma and COPD to risk of incident RA was supported by the National Institutes of Health. Dr. Sparks reported grant support from Amgen and Bristol Myers Squibb and consulting fees from Inova and Optum. Coauthors provided disclosures related to GlaxoSmithKline, AstraZeneca, Merck, Neutrolis, and Genentech.
SOURCE: Ford JA et al. Arthritis Rheumatol. 2020 Mar 4. doi: 10.1002/art.41194.