For a study, researchers wanted to determine if certain respiratory disorders are linked to an increased incidence of rheumatoid arthritis (RA). A case-control study matched newly diagnosed RA cases to 3 controls based on age, sex, and electronic health record history in the Mass General Brigham Biobank. Researchers used a validated method to detect RA, which was then confirmed through a review of medical records. At least 2 years before the index date of RA clinical diagnosis or the matching date, respiratory tract disease exposure required 1 inpatient or 2 outpatient codes. After controlling for covariates, logistic regression models calculated ORs for RA with 95%CI. The results were then stratified by smoking and serostatus (“seropositive” meant having positive rheumatoid factor and/or anti-citrullinated protein antibodies).

Researchers identified 741 RA cases and 2,223 controls (both median age 55, 76% female). Acute sinusitis (OR 1.61, 95% CI 1.05–2.45), chronic sinusitis (OR 2.16, 95% CI 1.39–3.35), and asthma (OR 1.39, 95% CI 1.03–1.87) were associated with increased risk of RA. Acute respiratory tract disease burden during the pre-index exposure period was also associated with increased RA risk (OR 1.30 per 10 codes, 95% CI 1.08–1.55). Acute pharyngitis was associated with seronegative (OR 1.68, 95% CI 1.02–2.74) but not seropositive RA; chronic rhinitis/pharyngitis was associated with seropositive (OR 2.46, 95% CI 1.01–5.99) but not seronegative RA. Respiratory tract diseases tended towards higher associations in smokers, especially greater than10 pack-years (OR 1.52, 95% CI 1.02–2.27, P=0.10 for interaction). Sinusitis, pharyngitis, and acute respiratory load all raised the risk of RA. The upper respiratory tract may be involved in the mucosal paradigm of RA development.