TNF and obesity due to melanocortin 4 receptor deficiency: In addition, previous studies have found that BMI is associated with higher disease activity, including elevated CRP levels.[21,22] Less effect of TNF-α inhibitors on disease activity and physical functioning has been found in obese or overweight axSpA and AS patients.[23,24] Additional analysis in the present study also showed higher disease activity over time in patients with overweight or obesity (data not shown).