Background Obesity is an increasing condition. Previous transversal studies suggested that obesity in patients with rheumatoid arthritis (RA) was associated with a higher disease activity, a poor quality of life and a lower radiographic damage but longitudinal studies are lacking.
Objectives We aimed to evaluate the impact of obesity at RA diagnosis on disease course including disease activity, health assessment questionnaire (HAQ-DI) and radiographic progression during the 3 first years.
Methods 628 patients from the French early arthritis ESPOIR cohort, fulfilling the 2010 ACR/EULAR criteria at baseline, were analyzed. Inclusion characteristics of normal weight (body mass index [BMI] 18.5 to 25), overweight (25-30) and obese (≥30 kg/m2) patients were compared using Khi2 and Kruskal Wallis. The outcome of DAS28 (and its components), HAQ-DI and Sharp score (and its components) was compared between BMI groups using repeated measures ANOVA and mixed models.
Results 353 patients had a normal BMI; 178 patients were overweight and 97 patients were obese. At baseline, obese patients were older and less frequently female, had lower rheumatoid factor levels, a higher Sharp score, lower C reactive protein and erythrocyte sedimentation rate, a higher insulin resistance, a lower practice of sport, higher IL-1RA and leptin levels, lower adiponectin and Dickkopf-related protein 1/sclerostin ratio. Repeated measures ANOVA showed a significant interaction between BMI groups and disease activity overtime with higher DAS28 (p=0.0002) (Fig. 1A), ESR (p=0.012) and disease activity on a visual analog scale (VAS) (p=0.002) and HAQ-DI (p=0.0001) (Fig. 1B) for obese patients. All these results were confirmed in mixed model using random effects model for time. Moreover, metabolic syndrome was associated with a higher DAS28 over time (p=0.011), independently of obesity. Total and erosion Sharp score were not significantly different between BMI groups whereas joint narrowing was significantly higher in obese patients (p=0.016)(Fig. 1C).
Conclusions Obesity at RA diagnosis is associated with a higher DAS28, a higher HAQ, a higher joint narrowing Sharp score over time but a similar total Sharp score than non-obese patients. Clinician should be aware of the differences that could influence the disease management.
Acknowledgements An unrestricted grant from Merck Sharp and Dohme (MSD) was allocated for the first 5 years of the ESPOIR study. Two additional grants from INSERM supported part of the biological database. The French Society of Rheumatology, Pfizer, Abbott, and Roche-Chugaï also supported the ESPOIR cohort.
Disclosure of Interest None declared