Majka et al1 have recently shown that higher age at the time of diagnosis of rheumatoid arthritis (RA) is associated with an increased period of prediagnosis antibody positivity for rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP). We have extended this observation using a previously described RA cohort (n = 79) in which serial preclinical serum samples were available, in most cases preceding and following seroconversion, thereby enabling approximation of the age at seroconversion.2 A total of 32 patients were anti-CCP positive and 22 patients were IgM-RF positive in the preclinical period. The age at seroconversion and the period of seropositivity before onset of …