Background There is wide scientific evidence about the involvement of smoking in the susceptibility to rheumatoid arthritis. However, the effect of smoking on the activity of the disease and its clinical course is controversial.
Objectives To analyze the impact of smoking on disease activity in a cohort of patients with recent onset rheumatoid arthritis.
Methods We included a cohort of patients from an Early Arthritis Clinic (EAC), followed up between January 1993 and December 2012. All patients gave informed consent to the study. Patients were included with early arthritis (less than one year of disease duration to the onset), who met the criteria of the American College of Rheumatology (ACR) 1987 for RA at some time during the disease course, and were followed up for two years. Microcrystalline and infectious arthritis were excluded, as well as patients who previously had been treated with disease modifying antirheumatic drugs. Patients were monitored for clinical and analytical data using standardized protocols every six months. The influence of active smoking in disease activity, functional disability and serological variables were studied. Every six months we assessed: number of tender (out of 68) joints (NTJ), number of swollen (out of 68) joints (NSJ), DAS, change in DAS (ΔDAS), HAQ, erythrocyte sedimentation rate (ESR), rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA).
Results 398 patients were included in the study, with a mean age at onset of 51.8 years (± 16.1 SD) and a predominance of women (77.6%). Patients were referred to the EAC with a mean of 17.7 weeks (± 13.1 SD) from the onset of symptoms. Active smokers were 27.6% of the patients. At baseline most patients had a subacute (88.7%), symmetrical (88.9%), RF-positive (81.3%), ACCP-positive (67, 5%) polyarthritis (83.1%). Smokers were younger at disease onset (49 ± 13.4 years smokers vs. 52.9 ± 13.4 in nonsmokers, p = 0.022), with a predominance of males (43% males vs. 23% women, p <0.001), positive RF (30.5% vs. RF positive. 13.4% RF negative, P = 0.005) and positive ACPA (35.2% ACPA-positive vs. 16.2% ACPA-negative; p <0.001). No significant differences in relation to smoking were found in terms of extension, course, symmetry, NTJ, NSJ, DAS, HAQ and ESR at months 0, 6, 12, 18 or 24. However, improvement in disease activity in active smokers was lower at 12 months (ΔDAS 1.29 ± 0.99 in smokers vs. 1.66 ± 1.30 in nonsmokers, p = 0.032) and at 24 months (ΔDAS 1.28 ± 1.20 in smokers vs. 1.9 ± 1.22 in non-smokers, p = 0.004).
Conclusions Active smoking has a negative impact on the activity of patients with recent onset rheumatoid arthritis, with less improvement as compared to non-smokers.
Disclosure of Interest None Declared