Background:Rheumatoid arthritis (RA) is associated with increased body mass index (BMI)- 60% of patients are either overweight or obese. Obesity in RA has been shown to predict reduced response to biologic therapy including tumour-necrosis-factor inhibitors (TNFi) [1]. However, it is not clear whether increased BMI influences response to all TNFi drugs in RA.Objectives:1.To explore whether BMI is associated with response to TNFi in patients with established rheumatoid arthritis (estRA), including those newly-starting on these drugs.Methods:Participants with estRA (>1year since diagnosis) taking biologic medications, registered on METEOR (international database of RA patients), 2008-2013, were included. EULAR response, DAS28 remission (including components), and treatment regimens were recorded at baseline, 6, and 12 months. WHO definitions of overweight (BMI≥ 25) and obese (BMI≥30) were explored as predictors of TNFi response (good EULAR response and DAS28 remission) using normal BMI as comparator. Logistic and linear regression models (controlling for age, gender, smoking, and baseline outcomes) and sensitivity analyses were performed. Subgroup analyses were performed for grouped TNFi and individual TNFi (infliximab, IFX; adalimumab, ADA; etanercept, ETN).Results:247 patients with estRA were taking a biologic at 6 months, and 231 patients were taking a biologic at 12 months. Obese patients taking any biologic were significantly less likely to achieve DAS28 remission (OR 0.33 [95%CI 0.12-0.80]) or good EULAR response (OR 0.37 [95%CI 0.16-0.81]) after 6 months, compared to those of normal BMI; this was also demonstrated in those co-prescribed methotrexate (DAS28 remission: OR 0.23 [95%CI 0.07-0.62]; good EULAR response: OR 0.39 [95%CI 0.15-0.92]). These associations did not remain statistically significant at the 12 months assessment.Regarding specific anti-TNF therapies, RA patients treated with monoclonal antibody (-mab) TNFis (IFX/ADA/ GOL) were significantly less likely to achieve good EULAR response at 6 months if they were obese RA (n=38), compared to those of normal weight (n=44) (OR 0.17 [95%CI 0.03-0.59]). A similar non-significant difference was demonstrated for DAS28 remission, and 12-month remission. Specifically, obese individuals were significantly less likely to achieve good EULAR response at 6 months with IFX (OR 0.09 [95%CI 0.00-0.61]; n=20), and significantly less likely to achieve DAS28 remission at 6 months when newly-starting ADA (OR 0.14 [95%CI 0.01-0.96]; n=17), compared to those of normal weight. There were no significant differences in remission outcomes between individuals of different BMI taking ETN. A small number of individuals stopped taking their respective biologic after 6months; reason for cessation was not recorded.Similar outcomes were seen in patients already established on anti-TNF therapy, with overweight and obese individuals less likely overall to be in DAS28 remission at all time points.Conclusion:In established RA, obesity is associated with reduced treatment response to -mab TNFi. No association between increased BMI and response to ETA was observed. Using BMI to direct biologic drug choice could prove to be a simple and cost-effective personalised-medicine approach to prescribing.References:[1]Schäfer M, Meißner Y, Kekow J, Berger S, Remstedt S, Manger B, et al. Obesity reduces the real-world effectiveness of cytokine-targeted but not cell-targeted disease-modifying agents in rheumatoid arthritis. Rheumatology. 2019 Nov 20.Disclosure of Interests:Mrinalini Dey: None declared, Sizheng Steven Zhao: None declared, Robert J Moots: None declared, Robert B.M. Landewé Consultant of: AbbVie; AstraZeneca; Bristol-Myers Squibb; Eli Lilly & Co.; Galapagos NV; Novartis; Pfizer; UCB Pharma, Nicola Goodson: None declared
THU0185 The value of adalimumab trough levels and clinical assessments in predicting clinical response in patients with established rheumatoid arthritis and an inadequate response to methotrexate
