Ding NS, et al. - Researchers aspired to investigate whether body composition profile was associated with response to anti-tumour necrosis factor (TNF) therapy in Crohn's disease and could offer an alternative dosing paradigm. They concluded that body composition profiles did not correlate well with BMI. For dosing, myopenia was correlated with primary nonresponse with potential implications and served as an explanation for pharmacokinetic failure.

• A total of 106 anti-TNF naïve patients underwent anti-TNF therapy for Crohn's disease with body composition parameters analysed using CT scans to estimate body fat-free mass between January 2007 and June 2012.
• Primary nonresponse and secondary loss of response were the outcome measures.
• The researchers used COX-regression analysis with 3 year follow-up data.

• The researchers included 106 patients for analysis with 26 (24.5%) primary nonresponders and 29 (27.4%) with secondary loss of response to anti-TNF therapy.
• They ascertained sex-specific cut-offs for muscle and fat by stratification analysis.
• Primary nonresponse was correlated with low albumin (OR 0.94; 0.88-0.99, P = .04) and presence of myopenia (OR 4.69; 1.83-12.01, P = .001) when taking into account patient's medical therapy, severity of disease and body composition in univariate analysis.
• Presence of myopenia was associated with primary nonresponse (OR 2.93; 1.28-6.71, P = .01) in multivariate analysis.
• Immunomodulator therapy was correlated with decreased secondary loss of response (OR 0.48; 0.23-0.98, P = .04).
• In this study, BMI was poorly correlated with lean body mass (r² = 0.15, P = .54).