Paediatric reference values for total psoas muscle area

Abstract

Background: Sarcopenia, the unintentional loss of skeletal muscle mass, is associated with poor outcomes in adult patient populations. In adults, sarcopenia is often ascertained by cross-sectional imaging of the psoas muscle area (PMA). Although children with chronic medical illnesses may be at increased risk for muscle loss because of nutritional deficiencies, physical deconditioning, endocrine anomalies, and systemic inflammation, consistent quantitative definitions for sarcopenia in children are lacking. We aimed to generate paediatric reference values for PMA at two intervertebral lumbar levels, L3-4 and L4-5.

Methods: In this cross-sectional study, we analysed abdominal computed tomography scans of consecutive children presenting to the emergency department. Participants were children 1-16 years who required abdominal cross-sectional imaging after paediatric trauma between January 1, 2005 and December 31, 2015 in a large Canadian quaternary care centre. Children with a documented chronic medical illness or an acute spinal trauma at presentation were excluded. Total PMA (tPMA) at levels L3-4 and L4-5 were measured in square millimetres (mm2 ) as the sum of left and right PMA. Age-specific and sex-specific tPMA percentile curves were modelled using quantile regression.

Results: Computed tomography images from 779 children were included. Values of tPMA at L4-5 were significantly larger than at L3-4 at all ages, but their correlation was high for both girls (r = 0.95) and boys (r = 0.98). Amongst girls, tPMA 50th percentile values ranged from 365 to 2336 mm2 at L3-4 and from 447 to 2704 mm2 for L4-5. Amongst boys, 50th percentile values for tPMA ranged between 394 and 3050 mm2 at L3-4 and from 498 to 3513 mm2 at L4-5. Intraclass correlation coefficients were excellent at L3-4 (0.97, 95% CI 0.94 to 0.981) and L4-5 (0.99, 95% CI 0.986 to 0.995). Weight and tPMA were correlated, stratified by sex for boys (L3-4 r = 0.90; L4-5 r = 0.90) and for girls (L3-4 r = 0.87; L4-5 r = 0.87). An online application was subsequently developed to easily calculate age-specific and sex-specific z-scores and percentiles.

Conclusions: We provide novel paediatric age-specific and sex-specific growth curves for tPMA at intervertebral L3-4 and L4-5 levels for children between the ages of 1-16 years. Together with an online tool (https://ahrc-apps.shinyapps.io/sarcopenia/), these tPMA curves should serve as a reference enabling earlier identification and targeted intervention of sarcopenia in children with chronic medical conditions.

Keywords: Children; Chronic Disease; Sarcopenia.

Conflict of interest statement

Eberhard Lurz has received speaker honoraria from Nutricia and Abbvie, but there is no conflict with this manuscript. Binita Kamath has received an unrestricted educational grant from Mirum. She is a consultant for Mirum, Shire, and DCI. None of these activities are in conflict with this manuscript. Peter Jüni serves as unpaid member of the steering group of trials funded by Astra Zeneca, Biotronik, Biosensors, St. Jude Medical, and The Medicines Company and has received research grants to the institution from Astra Zeneca, Biotronik, Biosensors International, Eli Lilly, and The Medicines Company and honoraria to the institution for participation in advisory boards from Amgen but has not received personal payments by any pharmaceutical company or device manufacturer. Vicky L. Ng is a consultant for Albireo, but there is no conflict with this manuscript. Hiten Patel, Gerald Lebovic, Claudia Quammie, Jessica P. Woolfson, Manuela Perez, Amanda Ricciuto, Paul W. Wales, and Govind B. Chavhan declare that they have no conflict of interest.

© 2020 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of Society on Sarcopenia, Cachexia and Wasting Disorders.

Figures

Figure 1

Axial and sagittal images. Lumbar levels were determined on (A) sagittal computed tomography images, enabling identification of the L3–4 and L4–5 intervertebral levels (yellow lines). (B) The axial images corresponding to these levels were then examined to determine the psoas muscle area (red lines).

Figure 2

Weight distribution curves stratified by sex. Weight distribution curves (5th to 95th percentile) for (A) male and (B) female participants from the Hospital for SickKids (dashed lines) are compared with Center for Disease Control (CDC) growth charts (full lines). Weight curves differ significantly (P < 0.0001) for male and female participants, with this study's cohort being slightly heavier.

Figure 3

Total psoas muscle area (tPMA) at lumbar level L3–4 showing 5th to 95th percentiles for (A) male and (B) female participants. tPMA values at L3–4 increases with patient age.

Figure 4

Total psoas muscle area (tPMA) at lumbar level L4–5 showing 5th to 95th percentiles for (A) male and (B) female participants. tPMA values at L4–5 increases with patient age.

Figure 5

Correlations of weight and total psoas muscle area (tPMA) at lumbar levels L3–4 and L4–5 stratified by sex. Weight and tPMA highly correlate for male and female participants at L3–4 and L4–5, respectively. (Pearson's correlation coefficient r = 0.90 for boys at L3–4 and L4–5 and r = 0.87 for girls at L3–4 and L4–5). Upper and lower dashed lines represent upper and lower boundaries of the 95% reference range.