Objective: Cigarette smoking is known to increase rheumatoid factor (RF) and nodule formation in patients with rheumatoid arthritis (RA). In this study, we examined the influence of smoking on disease outcome at 3 years among patients newly presenting with inflammatory polyarthritis (IP).
Methods: We studied 486 patients with IP who were referred to the Norfolk Arthritis Register, of whom 323 (67%) satisfied the American College of Rheumatology 1987 criteria for RA. Smoking status was assessed at baseline. Disease outcome was assessed at 3 years, using measures of joint inflammation, functional disability, and radiologic damage. The influence of smoking on disease outcome was explored using logistic regression techniques, with patients who had never smoked as the referent group. Results are expressed as odds ratios (ORs), with their 95% confidence intervals (95% CIs).
Results: Current smokers were significantly more likely to be RF positive at baseline (47%) than were ex-smokers (34%) and never smokers (31%). After 3 years, rheumatoid nodules were significantly more common in smokers (13%) compared with ex-smokers/never smokers (4%), a relationship which persisted after adjusting for age and sex (OR 4.07, 95% CI 1.38-12). In contrast, after adjusting for age and sex, current smokers had significantly fewer swollen joints (OR 0.61, 95% CI 0.37-0.98). However, smoking status had no influence on the development of erosions or functional disability.
Conclusion: Despite smokers being more likely to develop nodules and to be RF positive, current smokers did not have higher levels of radiologic damage, and had fewer swollen joints. We hypothesize that this could be due to either the effect of cigarette smoking on the inflammatory response or other factors (e.g., reduced physical activity in smokers) which may limit joint inflammation and damage.