IL1B and obesity due to melanocortin 4 receptor deficiency: As previously observed in the normal population (36), stratifying ERA patients based on their BMI, obesity was related to less incidence of osteopenia/osteoporosis at disease onset as suggested by the significantly higher plasma levels of IL-1 receptor antagonist in obese naive to treatment RA patients, which might antagonize the potent osteoclastogenic effects of IL-1β (37).