Background:Obesity population are rising rapidly and have become a major health issue. Studies have shown that obesity is a low-grade inflammatory status characterized by increase in proinflammatory cytokines.Objectives:To examine the impact of overweight or obesity on disease activity and treatment responses to biologics in patients with ankylosing spondylitis (AS) in a real-world setting.Methods:Body mass index (BMI) is available in 1013 patients from the Chinese Ankylosing Spondylitis Imaging Cohort (CASPIC). Differences in clinical outcomes (such as BASDAI, ASDAS, BASFI, and ASAS HI) and treatment responses to biologics (ΔBASDAI and ΔASDAS) over 3, 6, 9, and 12 months are assessed between BMI categories (normal weight BMI <24 kg/m2; overweight BMI=24-28 kg/m2; obesity BMI ≥28 kg/m2) using Kruskal-Wallis test. The association between BMI and clinical characteristics and treatment responses to biologics was determined, and multivariate median regression analyses were conducted to adjust for confounders (such as age, gender, smoke, and HLA-B27).Results:Among 1013 patients with AS, overweight accounts for 33%, while obesity for 12.4%. There were significant differences between patients who were obese or overweight and those with a normal weight regarding clinical outcomes (BASDAI: 2.90/2.56 vs 2.21; ASDAS-CRP: 2.20/1.99 vs 1.81; BASFI: 2.13/1.69 vs 1.38; ASAS HI: 6.87/5.29 vs 5.12 and BASMI: 2.35/1.76 vs 1.62; all P<0.05). After adjusting for age, gender, smoke, and HLA-B27, obesity remained associated with higher disease activity (BASDAI: β=0.55, P=0.005; ASDAS-CRP: β=0.40, P<0.001), poorer functional capacity (BASFI: β=0.58, P=0.001), worse health index (ASAS HI: β=1.92, P<0.001) and metrology index (BASMI: β=0.71, P=0.013). For TNFi users, BMI was found to be negatively correlated with changes in disease activity (ΔBASDAI and ΔASDAS) in the multivariate regression model (all P<0.05), and overweight and obese patients showed an unsatisfactory reduction in disease activity during 3-month, 6-month, 9-month, and 12-month follow-up period, compared to normal weight patients (all P<0.05).Conclusion:Overweight or obesity impacts greatly on clinical outcomes and treatment responses to biologics in patients with ankylosing spondylitis, which argues strongly for obesity management to become central to prevention and treatment strategies in patients with AS.References:[1]Maachi M, Pieroni L, Bruckert E, et al. Systemic low-grade inflammation is related to both circulating and adipose tissue TNFalpha, leptin and IL-6 levels in obese women. Int J Obes Relat Metab Disord 2004;28:993–7.Figure 1.Changes of disease activity for TNFi users during 3-, 6-, 9- and 12-month follow-up according to BMI categories. a: vs. normal weight, P<0.05 in 3 months; b: vs. normal weight, P<0.05 in 6 months; c: vs. normal weight, P<0.05 in 9 months; d: vs. normal weight, P<0.05 in 12 months.Acknowledgments:We appreciate the contribution of the present or former members of the CASPIC study group.Disclosure of Interests:None declared
Further observations upon HLA-B27, Yersinia enterocolitica, and ankylosing spondylitis.