Background Weight could be expected to affect the response to biological therapies by simply reducing the mg/Kg dose in fixed dose regimens. Furthermore, adipose tissue produces a variety of pro-inflammatory cytokines (as TNFa, IL-6, IL- 1) whose role in Rheumatoid Arthritis (RA) activity, remains unclear.
Objectives The purpose of this study was to determine whether body mass index (BMI) is related with response to the biologic therapy adjusted to the weight (tocilizumab, infliximab) in RA patients.
Methods Patients with RA followed in our day-hospital and registered in BioReportAR who had complete information of baseline and 12th week visit were included. Only patients with intravenously weight-adjusted therapy were considered. The body mass index (BMI) at baseline was calculated. Sociodemoraphic and clinical data were collected using data from the BioReportAR. Spearman correlation coefficient was used to analyse correlation between BMI and disease activity at baseline and its change after 12 weeks. Comparison between BMI categories was performed using Kruskal-Wallis test. p-values <0,05 were considered as statistically significant.
Results 45 patients were included (86,7% women, mean disease duration 12,93±10,69 years, mean age 57,11±11,0 years), 20 receiving tocilizumab and 25 infliximab. The BMI mean was 25,55±3,92 kg/m2, and at baseline the mean DAS28 was 3,06±1,33.
No correlation between BMI and baseline DAS28 (r= -0,158; p=0,519), change DAS28 (r= -0,207; p= 0,177) and individual parameters of DAS calculation were observed. When we compared change in DAS 28 between BMI categories (BMI£25 kg/m2 and >25 kg/m2) it didn’t show difference (p=0.607).
Conclusions This study is the first that correlates tocilizumab and BMI. In this study, BMI was not associated with disease activity or response to tocilizumab or infliximab therapy. These negative results might be at least partially explained by the low number of patients with BMI 330 kg/m2 (only 6) or by using BMI as unique marker of adipose tissue.
Disclosure of Interest None Declared