Prior research
Several studies have investigated the effect of DMARDs, including bDMARDs like tumor necrosis factor inhibitors, on incident dementia in patients with RA.
Among this research is a study by Dr. Desai and colleagues that looked at comparative risk of AD and related dementia in 22,569 Medicare beneficiaries receiving tofacitinib (a JAK inhibitor), tocilizumab (an IL-6 inhibitor), or TNF inhibitors in comparison with abatacept (a T-cell activation inhibitor). No differentiating risk associations were found in this cohort study.
Other past studies include:
- A study comparing about 21,000 patients with RA and a non-RA cohort of about 62,000 found a 37% reduction in dementia development among RA patients receiving DMARDs. The effect was dose dependent, greater with high cumulative dosages, and was found in both men and women and in subgroups younger and older than 65 years.
- A retrospective study of electronic health records from 56 million adult patients identified a subset of patients with RA, psoriasis, ankylosing spondylitis, ulcerative colitis, or Crohn’s disease in whom systemic inflammation increased risk for AD through a mechanism involving TNF. The risk for AD in patients was lowered by treatment with etanercept, adalimumab, infliximab, or methotrexate, with larger reductions observed in younger patients than in older patients receiving TNF blockers.
- A propensity score–matched retrospective cohort study in 2,510 U.S. veterans with RA found that use of a TNF inhibitor reduced the risk of dementia by 36%, compared with control patients (HR, 0.64; 95% CI, 0.52-0.80), and the effect was consistent over 5-20 years post RA diagnosis.
- In a retrospective, multinational, matched, case-control study of patients older than 50 years with RA, prior methotrexate use was associated with lower dementia risk (OR, 0.71; 95% CI, 0.52-0.98). Use of methotrexate longer than 4 years demonstrated the lowest dementia risk (odds ratio, 0.37; 95% CI, 0.17-0.79).
These past studies, Dr. Sattui and colleagues pointed out, have multiple shortcomings, including case-control design, different definitions of exposure or outcomes, and inadequate control of confounders, underscoring the need for more rigorous studies.
Several authors of the CMS claims study disclosed research support, grants, and consulting fees from pharmaceutical companies. The research was supported by a grant from the National Institutes of Health. Dr. Desai disclosed that he has received funding from the National Institute on Aging for drug repurposing studies of dementia.