Table 3 Risk of ACPA-positive rheumatoid arthritis in subjects exposed to different combinations of alcohol and smoking
Alcohol consumptionNever smokingEver smoking
Exp ca/co*OR† (95% CI)Exp ca/co*OR† (95% CI)
EIRA (ACPA-positive RA)
Drinkers159/2691.0‡ (Referent)456/4921.7 (1.3 to 2.1)
Non-drinkers47/761.1 (0.7 to 1.7)73/334.2 (2.6 to 6.6)
p interaction¶<0.001
CACORA (ACPA-positive RA)
Drinkers63/1811.0‡ (Referent)183/2981.9 (1.3 to 2.7)
Non-drinkers20/291.9 (1.0 to 3.6)42/254.8 (2.7 to 8.5)
p interaction¶<0.001
  • *Number of exposed (Exp) cases (ca) and controls (co). †Adjusted for sex, age and residential area (EIRA only). ‡Reference category. ¶The proportion attributable to interaction between smoking status and lack of alcohol consumption was 0.6 (95% CI 0.5 to 0.7) for EIRA and 0.4 (95% CI 0.3 to 0.5) for CACORA.

  • ACPA, antibodies to citrullinated peptide antigens; CACORA, Case–Control Study on Rheumatoid Arthritis; EIRA, Epidemiological Investigation of Rheumatoid Arthritis; RA, rheumatoid arthritis.