High body mass index is associated with shorter retention of tumor necrosis factor-alpha blocker treatment in rheumatoid arthritis

Purpose: To evaluate the association between body mass index (BMI) and tumor necrosis factor a (TNF-a) blockers retention in patients with rheumatoid arthritis (RA). Patients and Methods: This prospective cohort study analyzed data about patients with RA who initiated TNF blockers from the Israeli registry of inflammatory diseases from 2011 to 2019. Patients were grouped by BMI: normal (BMI <24.9 kg/m2), overweight (BMI 25- 29.9 kg/m2), obese (BMI 30-34.9 kg/m2) and morbid obese (BMI ≥35 kg/m2). Treatment cessation due to inefficacy was defined as an “event” and therapy with a drug above 3 months was defined as a “course.” Kaplan-Meier survival curve was used to describe drug survival. Event-free survival was calculated using Cox regression with a hazard ratio and confidence interval of 95%. Results: The final analysis included 521 RA patients (80% females) treated with etanercept, infliximab, adalimumab or golimumab. Eight hundred and eighteen treatment initiations were included in the final analysis, 334 (41%) in the normal weight group, 261 (32%) in the overweight, 144 (17%) in the obese and 79 (10%) in the morbid obesity group. Three hundred and twenty-six (40%) treatment initiations were with etanercept, 215 (26%) with adalimumab 197 (24%) with infliximab, and 80 (10%) with golimumab. BMI was inversely associated with drug survival. Morbid obese patients were more likely to discontinue treatment compared with normal weight patients HR 2.28 (95% CI 1.67-3.10, p<0.01). This association remained significant for each drug type (except for golimumab) in a subgroup analysis. Adalimumab switch rate was higher compared to etanercept with HR =1.51 (95% CI 1.20-1.91, p<0.01), no other significant differences were noted between the other drugs. Conclusion: Morbid obese RA patients have lower TNF-α blocker retention compared to normal weight patients.