Ankylosing spondylitis is associated with an increased risk of dementia: A systematic review and meta-analysis

To investigate the relationship between ankylosing spondylitis (AS) and risk of dementia.

Potentially eligible studies that compared the risk of developing dementia between patients with AS and individuals without AS were identified from MEDLINE and EMBASE databases from inception to May 2019 using a search strategy that comprised terms for "dementia" and "ankylosing spondylitis". Eligible studies could be either cohort studies or case-control studies. For cohort design, eligible studies included patients with AS and comparators without AS and followed them for incident dementia. For case-control design, eligible studies included cases with dementia and controls without dementia and explored prior history of AS in both groups. Effect estimate and standard error from each study were extracted and combined together using the random effect, generic inverse variance. Funnel plot was used to assess for publication bias.

A total of 7091 articles were identified using the aforementioned search strategy. After 2 rounds of independent review by 3 investigators, 4 studies fulfilled the inclusion criteria and were included into the meta-analysis. The risk of developing dementia was significantly higher among patients with AS than individuals without AS with the pooled relative risk of 1.19 (95% CI 1.01-1.41; I²  = 76%). The funnel plot was relatively symmetric and was not suggestive of presence of publication bias.

A significantly 1.2 fold higher risk of developing dementia among patients with AS was demonstrated by this systematic review and meta-analysis.