Detecting Sarcopenic Obesity in Survivors of Pediatric Acute Lymphoblastic Leukemia: An Exploration of Body Mass Index and Triponderal Mass Index as Potential Surrogate Markers

Abstract

Survivors of pediatric acute lymphoblastic leukemia (ALL) often have altered body composition secondary to treatment effects, including sarcopenic obesity (SO), which increases the risk of both metabolic complications and frailty. SO is difficult to detect without using advanced imaging techniques to which access is often limited. To explore whether common clinical indices can reliably identify the presence of SO in a cohort of long-term survivors of ALL, the discriminatory capacity of body mass index (BMI) or triponderal mass index (TMI, kg/m 3 ) for detecting SO was assessed. Thresholds of BMI and TMI associated with overweight or obesity status had poor sensitivity (< 50%) and specificity for detecting SO. Total misclassification rates at these thresholds exceeded 50% and positive likelihood ratios were nonsignificant. Notably, TMI is more strongly correlated with elevated adiposity than is BMI in this survivor population (R 2 = 0.73 vs. 0.57), suggesting further exploration is warranted. Our study is limited by the sample size, precluding detailed regression analysis. This study highlights the challenges of identifying SO in survivors of pediatric ALL using common clinical indices. Prospective evaluation of additional potential surrogate markers in survivors, in conjunction with the component features of SO, should be a key focus of future research.

Sarcopenia in long‐term survivors of cancer in childhood and adolescence: A cross‐sectional study of calf muscle mass by peripheral quantitative computed tomography with an examination of the muscle–bone unit

“…The ALM Index was created by adjusting raw ALM values (kg) by height (m 2 ), as proposed by Van Itallie et al., 45 and Z scores for these values were generated by the Hologic software. In a previous publication, we defined SO as an Appendicular Lean Mass Index (ALMI) Z score ≤ 0 with concomitant increase in fat mass index (FMI) Z score ≥ 0 14,39 ; an identical categorization is applied for this analysis.…”

“…33,34 In a cohort of survivors of ALL in childhood and adolescence, we have published previously detailed body composition assessment data including metrics of fat, muscle, bone, and the relationships between measures taken using DXA, anthropometry, and pQCT (of bone, specifically) to highlight changes in body composition in these survivors, and in particular SO. 14,21,[35][36][37][38][39] In this paper, our primary objective is to determine the sensitivity and specificity of identifying sarcopenia and SO using calf muscle mass measured by pQCT compared to measures extracted from DXA. An explanatory secondary objective is to examine the relationships between bone geometry and strength (as published previously by our group) and calf muscle mass.…”

“…Diagram of peripheral quantitative computed tomography (pQCT) measurement sites in radius and tibia. Index (ALMI) Z score ≤ 0 with concomitant increase in fat mass index (FMI) Z score ≥ 014,39 ; an identical categorization is applied for this analysis.Bone and muscle composition was also assessed using pQCT as the index test. pQCT was performed by a single experienced operator with a Stratec XCT 2000 instrument (Stratec Medezintechnik) with the Stratec Analysis Software v.6.0 (Orthometrix), all with 0.2mm voxel size and 2.2-mm slice thickness.…”