Trends in incidence of dementia among patients with rheumatoid arthritis: A population-based cohort study

Objective: We aimed to assess the incidence of dementia over time in patients with incident rheumatoid arthritis (RA) as compared to non-RA referents. Methods: This population-based, retrospective cohort study included Olmsted County, Minnesota residents with incident RA by ACR 1987 criteria, diagnosed between 1980 and 2009. We matched non-RA referents 1:1 on age, sex, and calendar year and followed all individuals until 12/31/2019. Incident dementia was defined as two codes for Alzheimer's disease and related dementias (ADRD) at least 30 days apart. Cumulative incidence of ADRD was assessed, adjusting for the competing risk of death. Cox proportional hazards models calculated hazard ratios (HR) with 95% confidence intervals (CI) for incident ADRD by decade. Results: After excluding individuals with prior dementia, we included 897 persons with incident RA (mean age 56 years; 69% female) and 885 referents. The 10-year cumulative incidence of ADRD in individuals diagnosed with RA during the 1980s was 12.7% (95%CI:7.9–15.7%), 1990s was 7.2% (95%CI:3.7–9.4%), and 2000s was 6.2% (95%CI:3.6–7.8%). Individuals with RA diagnosed in 2000s had insignificantly lower cumulative incidence of ADRD than those in the 1980s (HR 0.66; 95%CI:0.38–1.16). The overall HR of ADRD in individuals with RA was 1.37 (vs. referents; 95%CI:1.04–1.81). When subdivided by decade, however, the risk of ADRD in individuals diagnosed with RA was higher than referents in the 1990s (HR 1.72, 95%CI:1.09–2.70) but not 2000s (HR 0.86, 95%CI:0.51–1.45). Conclusions: The risk of dementia in individuals with RA appears to be declining over time, including when compared to general population referents.