Low muscle mass and sarcopenia: common and predictive of osteopenia in inflammatory bowel disease

BackgroundBody composition is poorly studied in inflammatory bowel disease (IBD). Sarcopenia describes a loss of muscle mass and strength. AimTo assess the prevalence of low lean mass (LM), sarcopenia and associated morbidity in an adult IBD cohort. MethodsCross-sectional data were gathered on pre-menopausal 18- to 50-year-old patients with IBD. Whole-body dual-energy X-ray absorptiometry, anthropometric assessment and grip strength were performed. Low LM was defined as 1 s.d. below the population mean for appendicular skeletal muscle index [ASMI (kg)/height (m)(2)], and sarcopenia as both ASMI and grip strength 1 s.d. below population mean. Multivariate regression analyses were performed. ResultsOf 137 participants (median age 31 years, BMI 24.8kg/m(2)), 56% were male and 69% had Crohn's disease (CD). Low LM and sarcopenia were observed in 21% and 12% of patients, respectively, and osteopenia/osteoporosis in 38% of patients (mean lumbar spine t-score -0.3s.d. 1.1). Grip strength predicted low LM and sarcopenia better than did body mass index (BMI) (OR 4.8 vs. OR 0.7 for low-LM, P<0.05 both). Normal BMI was falsely reassuring in 72% and 76% of patients with low ASMI and sarcopenia, respectively. Low LM and sarcopenia (OR=3.6, P=0.03; OR=6.3, P=0.02; respectively), but not BMI nor fat mass, predicted osteopenia/osteoporosis. ConclusionsLow lean mass and sarcopenia are common in patients with IBD, and important to recognise as they predict osteopenia/osteoporosis. Grip strength testing should be incorporated into routine clinical practice to detect low lean mass deficits, which may go unrecognised using BMI alone.