Low muscle mass is associated with efficacy of biologics in Crohn's disease

Low muscle mass (LMM) can be a frequent complication in Crohn's disease (CD). We attempted to explore the effect of LMM on the efficacy of biologics in patients with CD.

The retrospective cohort study included moderate-to-severe CD patients treated with infliximab or ustekinumab, and appendicitis patients as control. The skeletal muscle area (SMA) of L3 was assessed to evaluate the patients' muscle mass. After propensity score matching, the impact of LMM on drug efficacy was assessed in CD patients.

A total of 269 patients with CD and 172 appendicitis patients were included. The CD group had lower skeletal muscle density and BMI, and a higher risk of developing LMM than the control group. BMI (OR = 0.48, p < 0.001) and previous use of biologics (OR = 2.94, p = 0.019) were found to be independently associated with LMM. LMM was found to be associated with a decrease in clinical response (at weeks 8-14), clinical remission (at weeks 8-14, 24-30 and 52) and biochemical remission (at week 52). At weeks 24-30 and 52, LMM was independently associated with loss of response (LOR). We found LMM could be a predictor of lower clinical remission at week 30, lower clinical remission at week 52 and a higher LOR rate at week 30 in infliximab. While in ustekinumab, LMM was associated with lower endoscopic remission at week 24, biochemical remission at week 52 and a higher LOR rate at weeks 24 and 52.

The prevalence of LMM was higher in the CD group compared to the control group. For CD patients with LMM, the efficacy of infliximab and ustekinumab was relatively poor in both the short-term and long-term.