Skeletal muscle depletion correlates with disease activity in ulcerative colitis and is reversed after colectomy

Background & aims The body composition of patients with ulcerative colitis (UC) remains unclear. This study evaluated body composition in adult patients with UC and the associations of body composition with disease activity and surgical intervention. Methods This study included 99 patients with UC, 105 with Crohn's disease (CD) and 60 controls. Skeletal muscle area (SMA), visceral fat area (VFA) and subcutaneous fat area (SFA) of the third lumbar vertebrae were evaluated by abdominal computed tomography. The effects of medical therapy and surgery on body composition in UC patients were determined. Results Sarcopenia was more frequent in UC patients (27.3%) than in controls (8.3%), but less frequent than in CD patients (59.0%). The prevalence of sarcopenia was significantly higher (33.8% vs. 4.5%, p < 0.001), and SMA (144.26 vs. 182.32 cm2, p < 0.001), skeletal muscle index (SMI) (52.22 vs. 65.52 cm2/m2, p < 0.001) significantly lower, in UC patients with high (≥6) than low (<6) Mayo score, but SFA and VFA were similar. The prevalence of sarcopenia and alterations in body composition were reversed, along with UC disease activity, following medical treatment or surgery. SMA and SMI correlated significantly with disease activity in UC patients. Multivariate analysis showed that sarcopenia (odds ratio, 8.49; 95% confidence interval, 1.80–40.10; p = 0.007) was a negative predictor of high Mayo score in UC patients. Sarcopenic patients with UC had high probability of need for colectomy in Kaplan–Meier survival curves. Conclusions Sarcopenia is associated with high disease activity and poor clinical outcome in UC patients. Medical treatment and colectomy have positive effects on sarcopenia and skeletal muscle depletion.