Table 1

Basic characteristics of patients with RA and control subjects*

Controls

(n = 1,004)

RA cases

(n = 1,313)

anti-CCP-positive RA

(n = 822)

anti-CCP-negative RA

(n = 145)

Female, No. (%)

864 (86.1)

1,170 (89.1)

734 (89.3)

128 (88.3)

Age (mean ± SD years)

36.7 ± 12.5

51.8 ± 12.2

51.7 ± 11.8

50.5 ± 11.3

Onset age (mean ± SD years)

-

40.6 ± 12.4

40.5 ± 12.1

38.5 ± 11.9

Ever-smokers, No. (%)

134 (13.5)

197 (15.3)

119 (14.6)

26 (17.9)

Erosive disease (%)

-

1,071 (81.6)

682 (83.0)

113 (77.9)

* Except where indicated otherwise, values are the number (%). Among patients with rheumatoid arthritis (RA), 1,288 were evaluated for ever smokers, and 967 were evaluated for anti--cyclic citrullinated peptide antibodies (anti-CCP). Among control subjects, 991 were evaluated for ever smokers. Out of these subjects, 311 cases and 392 controls had been included in a previous study by Cha et al. [20].

Bang et al. Arthritis Research & Therapy 2010 12:R115   doi:10.1186/ar3051