Investigating the bi-directional association of rheumatoid arthritis and thyroid function: a methodological assessment of Mendelian randomization: Bi-directional association between rheumatoid arthritis and thyroid function.

Our results illustrate the significant bi-directional causal effect of RA and AITD, which holds even in multiple competing risk factors. Clinical screening for thyroid dysfunction in RA patients deserves further attention, and vice versa.