Smoking at onset of rheumatoid arthritis (RA) and its effect on disease activity and functional status: experiences from BARFOT, a long-term observational study on early RA

Abstract

Objectives: To assess the effects of smoking on disease outcome in a large cohort of patients with early rheumatoid arthritis (RA).

Methods: Between 1996 and 2004, 1787 adult patients (disease duration ≤ 1 year) were included in the BARFOT early RA study in Sweden. Smoking status was recorded at inclusion in the study. Disease Activity Score using 28 joint counts (DAS28), C-reactive protein (CRP), Health Assessment Questionnaire (HAQ) score, rheumatoid factor (RF), antibodies to cyclic citrullinated peptide (anti-CCP), general health (GH) and pain visual analogue scales (VAS), and drug treatment were registered at inclusion and at follow-up at 3, 6, and 12 months. European League Against Rheumatism (EULAR) response and remission criteria were applied at 3, 6, and 12 months.

Results: The proportion of patients who smoked at inclusion in the study fell from 29% in 1996 to 20% in 2004. There were no significant differences in disease activity at inclusion stratified according to smoking status. At 12 months of follow-up, 18% of current smokers at inclusion, 12% of previous smokers, and 11% of never smokers had high disease activity (DAS28 > 5.1, p = 0.005). Significantly fewer current smokers were in remission at 12 months (33%) compared to never smokers (36%) and previous smokers (42%) (p = 0.013). Current smoking at inclusion independently predicted poor EULAR response up to 12 months of follow-up.

Conclusion: The present study gives some support to earlier data indicating that RA patients who smoke have a more active disease but further studies are needed to confirm this.

Acknowledgements

We thank Jan-Åke Nilsson for invaluable help with the statistical analyses. We are also grateful for the help provided by all our colleagues and staff in the hospitals contributing to the BARFOT study, for their cooperation and provision of data. This study was supported by grants from the Swedish Society of Medicine, the Swedish Rheumatism Association, the Research Department of the County Council of Halland, the Gothenburg District Rheumatology Foundation, and the Crafoord Foundation.

Members of the BARFOT study group

S Ajeganova, M Andersson, V Bala, S Bergman, K Forslind, I Hafström, C Keller, I Leden, B Lindell, I Petersson, C Schaufelberger, B Svensson, M Söderlin, A Teleman, J Theander, A Östenson.