Table 1

Characteristics of cases and controls

ACPA-positive 
cases
ACPA-negative casesControls
Exposed to passive smoking, n (%)180 (47)98 (48)876 (50)
Women, n (%)301 (78)137 (67)1293 (73)
Men, n (%)84 (22)67 (33)471 (27)
Scandinavian, n (%)333 (86)185 (91)1533 (87)
Mean age at disease onset (SD)52.8 (16.0)47.8 (15.3)
Disease duration since first symptom (SD)0.8 (1.1)0.9 (1.2)
Total, n3852041764
  • ACPA,¬† anti-cyclic citrullinated peptide antibodies.