Therefore, in the EAC, SERA, and tREACH cohorts, smoking was categorized as ‘current smokers’ versus ‘past/never smokers’. In studies from the literature, smoking data was only available as ‘ever’ versus ‘never smokers’. The meta-analysis revealed no significant association between smoking and ACPA-IgG single-positive RA (odds ratio [OR] 1.18 [0.97–1.44]; Fig. 3A). This evidence concerns the gene PRTN3 and rheumatoid arthritis.