Impact of smoking on the effectiveness of TNF-α inhibitors in patients with rheumatoid arthritis or Crohn’s disease

Abstract

Cigarette smoking may be associated with the augmentation of pro-inflammatory cytokines includingTumor Necrosis Factor-alpha (TNF-α), which may affect the outcomes of pharmacologicalagents such as TNF-α inhibitors. The purpose of this study was to investigate the impact of smokingon the effectiveness of TNF-α inhibitors in patients with rheumatoid arthritis (RA) or Crohn’sdisease (CD). We used systematic literature review methods. A total of 1,147 articles were selectedafter exclusion of duplicates through a database search. Among them, 28 articles were finally selectedthrough a review of titles and abstracts and a subsequent review of full articles. The effectivenessof TNF-α inhibitors in patients with RA or CD among the selected articles was summarizedby their smoking status. Meta-analysis was performed with random effect model. When currentsmokers were compared with non-smokers for response after adjustments through meta-analysisamong patients with RA, current smokers had 59% less response than non-smokers with statisticalsignificance (Pooled adjusted OR=0.41, 95% CI=0.17-0.95). In patients with CD, current smokerstended to have lower clinical response than non-smokers, but statistical significance was not shown. In subgroup analyses for luminar CD or fistulizing CD, current smokers tended to have a lower responsein luminar CD (Pooled OR=0.62, 95% CI=0.34-1.14), but smoking status was not associatedwith drug response in fistulizing CD. This study raises awareness of the adverse effects of smokingin terms of clinical response in patients treated with TNF-α inhibitors.