Table 3

Attributable proportion (AP) due to interaction between ever-cigarette smoking, ex-cigarette smoking and current cigarette smoking, respectively, and silica exposure, associated with the risk of developing ACPA-positive RA and RA overall, respectively, with 95% CI

Subjects exposed to silica
Smoking categoryCategory of RANumber of cases/controlsAP95% CI
Ever-cigarette smokingACPA-positive RA38/410.34−0.09 to 0.77
RA overall56/410.34−0.09 to 0.77
Ex-cigarette smokingACPA-positive RA17/280.02−0.77 to 0.81
RA overall28/280.14−0.53 to 0.81
Current cigarette smokingACPA-positive RA21/130.600.26 to 0.95
RA overall28/130.520.12 to 0.93
  • ACPA, antibodies against citrullinated peptide antigens; RA, rheumatoid arthritis.