A new study evaluated the correlation between elevated levels of anti-citrullinated protein antibodies (ACPA) prior to a diagnosis of rheumatoid arthritis (RA) and chronic obstructive pulmonary disease (COPD) and/or asthma.
“Prior studies have demonstrated a relationship between RA and subsequent COPD risk,” the researchers wrote. “Several case-control studies and retrospective cohorts were limited by the inability to investigate serologic status or account for smoking, a strong risk factor for both COPD and RA. Some studies found that this association is more pronounced in seropositive RA and independent of smoking.”
They further noted that, “Prior studies have also investigated the association between RA and asthma, with some showing that RA increased asthma risk, but these studies lacked data on ACPA status or smoking. A previous study suggested that airway abnormalities are more common in patients with pre-RA seropositivity than controls but was cross-sectional and did not study clinically diagnosed obstructive lung diseases.”
ACPA Levels Indicate COPD and Asthma Risk
The study, published in Arthritis Care & Research, included data from the Nurses’ Health Studies on women who had donated blood. Women who reported incident RA following blood draw were matched 1:3 to control patients based on age, cohort, year, and menopausal factors. The researchers defined pre-RA ACPA+ as “>99th percentile of control distribution by a research assay or by CCP2 in a subset.” Questionnaires were used to determine which patients went on to develop COPD and asthma after blood draw.
Final analysis included 283 pre-RA women and 842 control patients. For women who were eventually diagnosed with RA, blood draw was performed a mean 9.7 (SD=5.8) years prior to diagnosis. About one in five women (n=59, 20.8%) were pre-RA ACPA+. Over 21,489 person-years of follow-up, 107 cases of incident COPD and 105 incident cases of asthma were reported. When adjusting for covariates, including smoking pack-years, women with pre-RA ACPA+ were significantly more likely to develop COPD (hazard ratio [HR]=3.04; 95% confidence interval [CI], 1.33–7.00). Pre-RA ACPA+ was also correlated with a greater risk for asthma (HR=1.74; multivariable 95% CI, 0.72–4.24), as was pre-RA ACPA- (HR=1.65; 95% CI, 1.11–2.46).
“Women with elevated ACPA before RA diagnosis had increased risk for developing COPD compared to controls. Women who later developed RA were more likely to develop asthma, regardless of pre-RA ACPA status,” summarized the authors.