Table 3

Study population characteristics by autoantibody status (RF and anti-CCP2 positive) of the SERA cohort at their baseline visit with complete records

Descriptive variableAnti-CCP2(+) (n=44)RF(+) (n=106)RF(−) and anti-CCP2(−) (n=2009)p Value*
Age at baseline visit (mean±SD)44.0±15.846.8±14.544.1±14.00.16
Non-Hispanic whites (%)63.669.881.1<0.01
Sex (% female)72.772.668.60.58
Education (% >high school)68.284.981.80.04
Income (%≥$40 000 annually)63.684.075.70.02
Shared epitope (% positive)61.450.053.20.45
Ever smoker (% yes)31.840.638.90.59
Current smoker (% yes)6.810.412.20.49
  • *p Value calculated is an omnibus test of difference; analysis of variance for continuous variables, and χ2 test for categorical variables.

  • anti-CCP, anti-cyclic citrullinated peptide; RF, rheumatoid factor; SERA, Studies of the Etiology of RA.