Smoking, body mass index, disease activity, and the risk of rapid radiographic progression in patients with early rheumatoid arthritis

BACKGROUND: Identification of risk factors for rapid joint destruction in early rheumatoid arthritis (RA) can be helpful for optimizing treatment, and improving our understanding of destructive arthritis and its mechanisms. The objective of this study was to investigate the relationship between early RA patient characteristics and subsequent rapid radiographic progression (RRP).

METHODS: An inception cohort of patients with early RA (symptom duration < 12 months), recruited during 1995-2005 from a defined area (Malmö, Sweden), was investigated. Radiographs of the hands and feet were scored in chronological order according to the modified Sharp-van der Heijde score (SHS), by a trained reader. RRP was defined as an increase of ≥ 5 points in SHS per year.

RESULTS: Two hundred and thirty-three patients were included. Radiographs were available from 216 patients at baseline, 206 patients at 1 year, and 171 patients at 5 years. Thirty-six patients (22%) had RRP up to 5 years. In logistic regression models, rheumatoid factor (RF) and anti-cyclic citrullinated peptides (anti-CCP), and increased erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) at baseline, predicted RRP over 5 years. Patients identified as overweight or obese had a significantly reduced risk of RRP up to 5 years (odds ratio (OR) 0.26; 95% confidence interval (CI) 0.11-0.63; adjusted for RF, baseline erosions, and ESR). Similar point estimates were obtained when stratifying for antibody status, and in models adjusted for smoking. A history of ever smoking was associated with a significantly increased risk of RRP up to 5 years, independent of body mass index (BMI) (OR 3.17; 95% CI 1.22-8.28; adjusted for BMI). At the 1-year follow-up, erosive changes, Disease Activity Score of 28 joints, Health Assessment Questionnaire, swollen joint count, and patient's global assessment of disease activity and pain were also significantly associated with RRP up to 5 years.

CONCLUSIONS: A history of smoking, presence of RF and/or anti-CCP and early erosions, high initial disease activity and active disease at 1 year, all increase the risk of RRP. Patients with a high BMI may have a reduced risk of severe joint damage. This pattern was not explained by differences in disease activity or antibody status. The results of this study suggest independent effects of smoking and BMI on the risk of RRP.