Low muscle mass at initiation of anti-tumour necrosis factor therapy for inflammatory bowel disease is associated with early treatment failure.

Goals: We sought to determine whether low muscle mass at commencement of anti-tumour necrosis factor (TNF) therapy was associated with earlier treatment failure. Background(s): Delayed treatment failure occurs in significant proportion of inflammatory bowel disease (IBD) patients treated with TNF-alpha antagonists. Identification of predictors of loss of response may help optimize therapy. Study: A retrospective cohort study was performed of 67 patients who had undergone cross-sectional abdominal imaging at a single centre coincident with commencement of anti-TNF drugs. Analysis of the images at the third lumbar vertebra was performed using standard techniques to determine cross-sectional areas of skeletal muscle (SM), visceral adipose tissue, subcutaneous adipose tissue, and intermuscular adipose tissue. Treatment failure was defined as follows: a post-induction hospital admission or surgery for IBD, escalation of TNF dose or immunosuppressants for clinical loss of response, emergence of a new fistula, or rising Crohn's Disease Activity Index >150. Result(s): Two-thirds of patients had sarcopenia. Patients with less than the gender-specific median SM area had a median time to failure of 520 (SD 135) days compared with 1100 (SD 151) days for those with greater than median SM area (P = 0.036). No difference was found in disease duration, inflammatory markers, or Crohn's Disease Activity Index between quartiles of SM area. No relation between outcomes and measures of adipose tissue, weight, or body mass index was observed. Conclusion(s): Identifying low muscle mass at anti-TNF induction as a risk factor for treatment failure may contribute to a more tailored approach to IBD therapy.