PRTN3 and rheumatoid arthritis: Although the percentage of ever‐smokers was reduced among patients with BR/RA compared with that among patients with RA alone (42% versus 56%; P = 0.06), the rate of seropositivity in BR/RA patients compared with RA patients was significantly increased for each ACPA tested: for anti–CCP‐2, 88% versus 48%; for anti–CEP‐1, 60% versus 24%; for anti–Cit‐vimentin, 56% versus 20%; and for anti–Cit‐fibrinogen, 74% versus 40% (Table 2) (all P < 0.01).