Background Lifestyle related factors, such as smoking and Body Mass Index (BMI) are known to increase the disease activity and progression in rheumatoid arthritis (1,2). In ankylosing spondylitis (AS), only a few studies are available regarding this topic (3–5). Smoking was associated with an earlier diagnosis of AS, higher disease activity (OR=2.5) and a doubled increased radiographic progression compared to non smokers. In addition, alcohol consumption and having a physical demanding occupation were associated with more axial radiographic lesions. A higher BMI was associated with a lower response rate to Tumor Necrosis Factor inhibitors (TNFi) compared to AS patients with a normal BMI (49% vs 78%, respectively). Most studies included only one lifestyle related factor in association with disease activity and early diagnosis in AS, while our study aimed to test for multiple related lifestyle factors on disease activity and early diagnosis.
Objectives To determine whether factors related to lifestyle (smoking, alcohol consumption, BMI, physical activity and occupation) are associated with age at diagnosis of AS and response rate to TNFi.
Methods Consecutive AS patients (fulfilling the modified New York criteria) who started or switched treatment with TNF inhibitors were included in a prospective, observational cohort. Data on disease activity (Ankylosing Spondylitis Disease Activity Score (ASDAS) and lifestyle factors (smoking, alcohol consumption, BMI, occupation and physical activity) were collected at baseline and 6, 12 and 24 months after the start of treatment. Lifestyle factors, with p<0.05 in relation to age at diagnosis and ASDAS were subsequently entered in the overall regression model.
Results In total 312 AS patients were included with a mean follow-up of 18.9 months (6–24). The majority 172 (55%) improved on TNFi whereof, 86 patients (27.7%) showed a clinical important improvement (decrease in ASDAS >1.1) and 86 (27.7%) a major clinical improvement (decrease in ASDAS >2.2). In multivariate analysis, age at diagnosis was negatively influenced by a positive smoking status ((regression coefficient in years) B= -2.78, p=0.041, 95% CI= -5.60 – -0.01), being physical active (B=-2.98, p=0.026, 95% CI=-5.59 – -0.37) and having a normal BMI (B= -3.1, p=0.019, 95% CI=-5.73 – -0.52) (Figure 1). No risk factors were related with the change in ASDAS during treatment. No relation between alcohol consumption and disease onset or treatment response was found.
Conclusions Smoking, moderate physical activity and normal BMI were associated with an earlier age at diagnosis. A significant improvement of the ASDAS at both 1 and 2 year follow-up under TNF treatment was found, confirming the efficacy of TNF inhibitors in a real life cohort. However, contrary to the expectations no relations were found between lifestyle factors and disease activity.
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Disclosure of Interest None declared