Impact of Dual Rheumatoid Factor and Anticitrullinated Protein Antibody Seropositive, Single Seropositive, and Seronegative Rheumatoid Arthritis on Outcomes
Objective The objective of this study was to investigate the association between dual seropositive, single seropositive, and seronegative rheumatoid arthritis (RA) with radiographic erosions, disease flares, and death. Methods We performed a retrospective, population‐based study of residents in Southern Minnesota with incident RA who fulfilled criteria for RA in 2003 to 2019. Radiographic erosions and flares were evaluated within one year of incident RA. All‐cause mortality was obtained from medical records and death certificates. Cox models adjusted for age, sex, smoking status, year of incident RA, and comorbidities were used. Results The study included 1,373 patients with RA. At RA incidence, 37% were dual seropositive, 13% seropositive for anti–cyclic citrullinated protein (anti‐CCP) only, 12% seropositive for rheumatoid factor (RF) only, and 38% seronegative. The highest proportion of radiographic erosions before or within one year of RA incidence was in the dual seropositive (31%) and lowest in those seropositive for anti‐CCP only (13%). Flares occurred in 69% of the dual seropositive and 51% of the seropositive for anti‐CCP only within the first year of RA incidence. Those seropositive for RF only had over a two‐fold increase in mortality rates compared with the seronegatives (adjusted hazard ratio [aHR] 2.18, 95% confidence interval [CI] 1.47–3.24). In contrast, the dual seropositives had only a >50% increase in mortality rates (aHR 1.66, 95% CI 1.21–2.28), and those seropositive only for anti‐CCP had a >30% increase in mortality rates (aHR 1.32, 95% CI 0.83–2.11). Conclusion Patients with RA seropositive for RF only have an increase in mortality rates compared with patients who are dual seronegative. RF positivity could be an indicator of inflammation that requires pharmacologic treatment to decrease mortality rates.
ObjectiveWe aimed to evaluate lung cancer risk in patients with rheumatoid arthritis (RA) and RA‐interstitial lung disease (ILD).MethodsWe performed a retrospective, matched cohort study of RA and RA‐ILD within the Veterans Health Administration (VA) between 2000 and 2019. Patients with RA and RA‐ILD were identified with validated administrative‐based algorithms, then matched (up to 1:10) on age, gender, and VA enrollment year to individuals without RA. Lung cancers were identified from a VA oncology database and the National Death Index. Conditional Cox regression models assessed lung cancer risk adjusting for race, ethnicity, smoking status, Agent Orange exposure, and comorbidity burden among matched individuals. Several sensitivity analyses were performed.ResultsWe matched 72,795 patients with RA with 633,937 patients without RA (mean age 63 years; 88% male). Over 4,481,323 patient‐years, 17,099 incident lung cancers occurred. RA was independently associated with an increased lung cancer risk (adjusted hazard ratio [aHR] 1.58 [95% confidence interval (CI) 1.52–1.64]), which persisted in never smokers (aHR 1.65 [95% CI 1.22–2.24]) and in those with incident RA (aHR 1.54 [95% CI 1.44–1.65]). Compared to non‐RA controls, prevalent RA‐ILD (n = 757) was more strongly associated with lung cancer risk (aHR 3.25 [95% CI 2.13–4.95]) than RA without ILD (aHR 1.57 [95% CI 1.51–1.64]). Analyses of both prevalent and incident RA‐ILD produced similar results (RA‐ILD vs non‐RA aHR 2.88 [95% CI 2.45–3.40]).ConclusionRA was associated with a >50% increased risk of lung cancer, and those with RA‐ILD represented a particularly high‐risk group with an approximate three‐fold increased risk. Increased lung cancer surveillance in RA, and especially RA‐ILD, may be a useful strategy for reducing the burden posed by the leading cause of cancer death.