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

Background & Aims: 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.
Methods: 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.
Results: 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)cm ² /m ² . Mean BMI pre-PS was 22.1 (4.8) kg/m ² . Both BMI (22.1 kg/m ² to 23.5 kg/m ² ) p < 0.001) & LSMI (36.5 cm ² /m ² to 38.4 cm ² /m ² ) (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).
Conclusions: 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.
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