SARCOPENIA AT INITIAL DIAGNOSIS OF PEDIATRIC INFLAMMATORY BOWEL DISEASE
Authors: Rompca Annemarie , McLuckey Morgan , Perkins Anthony , Vanderpool Charles , Zhang Xiaoyi 
Published: January 2024

Abstract

BACKGROUND
Inflammatory bowel disease (IBD) can impact patients’ nutritional status. Poor oral intake, poor nutrient absorption, stool protein loss, and increased energy requirement all contribute. Poor nutritional status can manifest as inadequate growth, reduced weight gain, and sarcopenia, defined as decreased muscle mass and strength. Studies demonstrate decreased muscle mass in pediatric IBD patients leads to higher rates of therapy escalation, surgery, and post-operative complications. We sought to obtain the muscle mass at IBD diagnosis via cross-sectional imaging, compare to pediatric age- and sex-specific psoas muscle reference values for pediatric norms, and analyze muscle mass comparison between IBD subtypes and correlations with anthropometrics at diagnosis.

METHODS
Patients with new diagnosis of IBD [Crohn’s disease (CD), ulcerative colitis (UC), and indeterminate colitis (IC)] aged 6-16 at diagnosis during 1/01/2016 through 12/31/2019 at our tertiary care facility were included in this retrospective study. Those with chronic medical conditions and lack of cross-sectional imaging within 3 months of diagnosis were excluded. Demographic and anthropometric data at diagnosis of IBD were obtained. The psoas muscle area in mm2 was measured on cross-sectional imaging at lumbar level 3-4 (L3-4) and 4-5 (L4-5) bilaterally to obtain total psoas muscle area (TPMA) at each level and compared to pediatric reference values. Statistical analysis included analysis of variance and Spearman correlations, performed using SAS v9.4.

RESULTS
Cross-sectional imaging from 162 patients with newly diagnosed IBD were reviewed. Average age was 12.1 years, with male predominance of 93 patients (57.4%). Most patients were diagnosed with CD (n=119, 73.5%), followed by UC (n=39, 24.1%), and IC (n=4, 2.5%) (Table 1). Measures of sarcopenia at both lumbar levels for TPMA and both lumbar levels z-score showed significant difference across IBD subtypes (Table 2).

CONCLUSIONS
Negative mean TPMA z-score &lt; -1 was noted in all patients at both L3-4 and L4-5 levels, with a statistically significant difference between IBD types and mean TPMA at L3-4, TPMA at L4-5, mean z-score at L3-4, and mean z-score at L4-5. In a subgroup analysis, UC patients were significantly different from CD patients on all four measures, suggesting a higher rate of sarcopenia in CD patients at diagnosis. We plan to expand analysis to compare sarcopenia with disease location, medical therapy, hospitalization rate, need for surgical intervention, and anthropometrics over time. We hope to underscore importance of sarcopenia as measure of nutritional status at diagnosis, particularly when patients present with normal anthropometrics.

Table 1

Table 2

SUBGROUP COMPARISONS
Ulcerative Colitis patients were significantly different from Crohn’s Disease patients on all 4 measures.
Indeterminate Colitis patients were significantly different from Ulcerative Colitis patient on the 2 Total Psoas Muscle Area Measures.