Associations of cigarette smoking with rheumatoid arthritis in African Americans

Arthritis Rheum. 2010 Dec;62(12):3560-8. doi: 10.1002/art.27716.

Abstract

Objective: To examine the associations of cigarette smoking with rheumatoid arthritis (RA) in African Americans, and to determine whether this association is impacted by the HLA-DRB1 shared epitope (SE).

Methods: Smoking status, cumulative smoking exposure, and SE status were determined in African American patients with RA and African American healthy controls. Associations of smoking with RA were examined using age- and sex-adjusted logistic regression analyses. Additive and multiplicative SE-smoking interactions were examined.

Results: After adjustment for age and sex, ever smoking (odds ratio [OR] 1.45, 95% confidence interval [95% CI] 1.07, 1.97) and current smoking (OR 1.56, 95% CI 1.07, 2.26), relative to never smoking, were more common in African American patients with RA (n = 605) than in controls (n = 255). The association of smoking with RA was limited to those with a cumulative exposure exceeding 10 pack-years, associations that were evident both in autoantibody-positive and in autoantibody-negative disease. There was evidence of a significant additive interaction between SE status and heavy smoking (≥10 pack-years) in relation to RA risk (attributable proportion [AP] due to interaction 0.58, P = 0.007), with similar results for the additive interaction between SE status and ever smoking (AP 0.47, P = 0.006). There was no evidence of multiplicative interactions.

Conclusion: Among African Americans, cigarette smoking is associated not only with the risk of autoantibody-positive RA but also with the risk of autoantibody-negative disease. The risk of RA attributable to smoking is limited to African Americans with more than 10 pack-years of exposure and is more pronounced among individuals positive for the HLA-DRB1 SE.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • African Americans* / genetics
  • Aged
  • Alleles
  • Arthritis, Rheumatoid / epidemiology*
  • Arthritis, Rheumatoid / genetics
  • Arthritis, Rheumatoid / immunology*
  • Autoantibodies / blood
  • Case-Control Studies
  • Epitopes / genetics
  • Female
  • HLA-DR Antigens / blood
  • HLA-DR Antigens / genetics
  • HLA-DRB1 Chains
  • Humans
  • Logistic Models
  • Male
  • Middle Aged
  • Risk Factors
  • Smoking / adverse effects*
  • Time Factors

Substances

  • Autoantibodies
  • Epitopes
  • HLA-DR Antigens
  • HLA-DRB1 Chains