Table 1

Characteristics of rheumatoid arthritis cases and controls in the MyEIRA study

All

Men

Women

Cases n = 1,056

Controls n = 1,416

Cases n = 151

Controls n = 211

Cases n = 905

Controls n = 1,205

Age, mean (SD) years

47.7 (11.5)

47.1 (11.4)

50.1 (11.9)

49.8 (11.9)

47.3 (11.4)

46.7 (11.3)

Smoking status

Never-smoker, n (%)

927 (88)

1,260 (89)

61 (40)

101 (48)

866 (96)

1159 (96.2)

Ever-smoker, n (%)

79 (7)

65 (5)

70 (46)

60 (28)

9 (1)

5 (0.4)

Information missing on smoking, n (%)

50 (5)

91 (6)

20 (14)

50 (24)

30 (3)

41 (3.4)

Ethnic group

Malay

441 (42)

893 (63)

66 (44)

126 (60)

375 (41)

767 (64)

Chinese

217 (20)

183 (13)

36 (24)

31 (15)

181 (20)

152 (13)

Indian

323 (31)

253 (18)

37 (25)

43 (20)

286 (32)

210 (17)

Others

75 (7)

87 (6)

12 (8)

11 (5)

63 (7)

76 (6)

ACPA status

ACPA-positive RA, n (%)

680 (64)

32 (2)

104 (69)

5 (2)

576 (64)

27 (2)

ACPA-negative RA, n (%)

376 (36)

1,383 (98)

47 (31)

206 (98)

329 (36)

1,177 (98)

Presence of SE alleles

None SE alleles, n (%)

629 (60)

1,183 (84)

83 (55)

181 (86)

546 (60)

1,002 (83)

Any SE alleles, n (%)

425 (40)

233 (16)

68 (45)

30 (14)

357 (39)

203 (17)

ACPA, anti-citrullinated peptide antibody; DNA, deoxyribonucleic acid; MyEIRA, Malaysian Epidemiological Investigation of rheumatoid arthritis; RA, rheumatoid arthritis; SD, standard deviation; SE, shared epitope. The "any SE alleles" group was defined by the presence of either one or two HLA-DRB1*01:01, *01:02, *01:07, *04:01, *04:04, *04:05, *04:08, *04:10, *10:01, and/or *10:03 SE alleles.

Too et al. Arthritis Research & Therapy 2012 14:R89   doi:10.1186/ar3813