Survival and CT defined sarcopenia in patients with intestinal failure on home parenteral support

Sarcopenia occurs in patients with intestinal failure (IF) and has been associated with poorer survival in several chronic diseases. CT can measure sarcopenia through a L3 skeletal muscle index (LSMI). We aim to describe the prevalence of sarcopenia in a section of our IF population using LSMI, & evaluate the effect of home parenteral support (PS) on LSMI & survival. Additionally, we aim to assess any association between LSMI, BMI & other anthropometric measurements.

IF patients on PS treated at St Mark's Hospital between 1/1/2006-1/10/2016 were identified from a prospectively maintained database. Patients were included if they were on PS & had 2 CTs: the first ≤30 days before start of HPN (pre-PS); the second ≥100 days from PS start (post-PS). Patient records were reviewed to obtain clinical & demographic information & date of death. Anthropometric measurements & BMI contemporaneous to CT scans were recorded.

64 patients met inclusion criteria (M:F 1:1). 83% of our cohort had LSMI below previously published thresholds for sarcopenia. Mean (SD) pre-PS LSMI was 36.5 (6.8)cm²/m². Mean BMI pre-PS was 22.1 (4.8) kg/m². Both BMI (22.1 kg/m² to 23.5 kg/m²) p < 0.001) & LSMI (36.5 cm²/m² to 38.4 cm²/m²) (p = 0.003) increased post-PS. A positive correlation was seen between BMI & LSMI pre (r = 0.47 p < 0.001) & post-PS (r = 0.37 p = 0.003). No correlation was seen between LSMI & anthropometric measurements pre-PS (p = 0.78) or post-PS (p = 0.96). 11 (17%) patients died during the study period; a low LSMI pre-PS was not a risk factor for mortality (HR 0.97 p = 0.55).

This study is the first to look at sarcopenia & survival using CT defined LSMI (CT-LSMI) in the IF population. 83% of our cohort had a pre-PS LSMI below previously published thresholds, yet we found no relationship between lower baseline LSMI & survival. This may reflect the heterogeneity of the prognoses of the IF population, or that parenteral nutrition itself affects survival. Our study showed that LSMI & BMI improved following PS but demonstrated that other anthropometric measurements had poor correlation with LSMI & showed no significant improvement overall after PS, confirming the known problems of inter-operator & patient variability of these measurements. Whilst we found significant correlation between LSMI & BMI, BMI significantly underestimated the presence & degree of sarcopenia. LSMI has the potential to provide an objective & reproducible measure of sarcopenia in IF. Future larger studies should be performed to evaluate associations with patient outcomes & utility in clinical decision making.