Incidence of dementia in patients with rheumatoid arthritis and association with disease modifying anti-rheumatic drugs - Analysis of a national claims database.

OBJECTIVE: To evaluate the risk of incident dementia associated with the use of biologics or targeted synthetic DMARDs (b/tsDMARD) compared to conventional synthetic (cs) DMARDS only in patients with rheumatoid arthritis (RA). METHODS: We analyzed claims data from the Center for Medicare & Medicare Services (CMS) from 2006-2017. Patients with RA were identified as adults ≥40 years old and two RA diagnoses by a rheumatologist > 7 and < 365 days apart. Patients with a prior diagnosis of dementia were excluded. Use of cs/b/tsDMARDs was the exposure of interest. Person-time was classified as either: 1) b/tsDMARD exposed, which included tumor necrosis factor alpha inhibitors (TNFi)-bDMARDs, non-TNFi-bDMARDs or tsDMARDs with or without csDMARDs; 2) csDMARD-exposed: any csDMARD without b/tsDMARD. Patients could contribute time to different exposure groups if they changed medications. Incident dementia was defined as: 1 inpatient OR 2 outpatients ICD-9-CM or ICD-10 claims for dementia, OR prescription of a dementia-specific medication (rivastigmine, galantamine, memantine, donepezil, tacrine). Age-adjusted incident rates (IR) were calculated, and univariate and multivariate Cox proportional hazard models were used to calculate Hazard Ratios (HR) and 95% confidence intervals (CI). RESULTS: We identified 141,326 eligible RA patients; 80% female and 75.3% white, median age 67 years and mean (SD) exposure time of 1.1 (1.5) years. There were 233,271 initiations of c/b/tsDMARDS and 3,794 cases of incident dementia during follow up. The crude IR of dementia was 2.0 (95% CI 1.9-2.1) per 100 person-years for patients on csDMARDs and 1.3 (95% CI 1.2-1.4) for patients on any b/tsDMARD. Patients on b/tsDMARDs had an adjusted 19% lower risk for dementia than patients on csDMARDs [HR 0.81 (95% CI 0.76-0.87)]. Subgroup analysis found comparable risk reductions between TNFi, non-TNFi, and tsDMARDs. on the risk of dementia. CONCLUSIONS AND RELEVANCE: The incidence of dementia in patients with RA was lower in patients receiving b/tsDMARDs when compared to patients on csDMARD only. No differences were observed between different classes of b/tsDMARDs, suggesting that decreased risk is possibly explained by the overall decrease in inflammation rather than a specific mechanism of action of these drugs.