Table 3

Rheumatoid Arthritis associated with coal mining and other silica exposure, stratified on smoking status

Stratified modelsModel nRA
Prevalence
ExposureInteraction term
Coal±other SilicaNon-coal Silica
Pe rcentORs (95% CI) for RAP value
Never and ever smokers0.84
 Never smokers72983.0 (1.7 to 5.2)2.9 (1.8 to 4.8)
 Ever smokers878133.8 (2.5 to5.8)3.5 (2.4 to 5.1)
Former and current smokers*0.02
 Former smokers615125.4 (3.3 to 9.0)3.5 (2.2 to 5.5)
 Current/recent smokers263151.6 (0.8 to 3.6)3.2 (1.7 to 6.2)
Shorter and longer smoking*0.02
 <25 years441116.5 (3.5 to 12.1)4.0 (2.2 to 7.3)
 ≥25 years419152.1 (1.2 to 3.7)3.1 (1.8 to 5.1)
  • RA definition based on report of provider’s diagnosis of RA, plus treatment with glucocorticoids.

  • Results from logistic regression models controlling for age. All models exclude non-RA arthritis.

  • Reference group for coal/silica exposure is neither coal nor silica exposure.

  • Interaction term for coal/silica exposure with smoking status shown.

  • Recent smokers include those who stopped in past 3 years.

  • Combined datasets (2017 and 2019 surveys).

  • *Never smokers and unknown smoking status excluded. Smoking duration missing, n=37.

  • RA, rheumatoid arthritis.