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.

中文翻译：

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腰大肌总面积的儿科参考值。

背景 肌肉减少症，即骨骼肌质量的无意损失，与成年患者群体的不良结果有关。在成人中，肌肉减少症通常通过腰大肌区域 (PMA) 的横截面成像来确定。尽管由于营养缺乏、身体机能失调、内分泌异常和全身性炎症，患有慢性疾病的儿童肌肉损失的风险可能会增加，但缺乏对儿童肌肉减少症的一致定量定义。我们旨在为两个椎间腰椎水平 L3-4 和 L4-5 生成 PMA 的儿科参考值。方法 在这项横断面研究中，我们分析了就诊于急诊科的连续儿童的腹部计算机断层扫描。参与者是 1-16 岁的儿童，他们在 2005 年 1 月 1 日至 2015 年 12 月 31 日期间在加拿大一家大型四级护理中心接受儿科创伤后需要腹部横断面成像。在就诊时患有慢性疾病或急性脊柱外伤的儿童被排除在外。L3-4 和 L4-5 水平的总 PMA (tPMA) 以平方毫米 (mm2 ) 为单位测量，作为左右 PMA 的总和。使用分位数回归对特定年龄和特定性别的 tPMA 百分位曲线进行建模。结果 包括来自 779 名儿童的计算机断层扫描图像。L4-5 的 tPMA 值在所有年龄段均显着大于 L3-4，但其相关性在女孩 (r = 0.95) 和男孩 (r = 0.98) 中均较高。在女孩中，tPMA 第 50 个百分位值范围为 L3-4 的 365 至 2336 mm2 和 L4-5 的 447 至 2704 mm2。在男孩中，tPMA 的第 50 个百分位值在 L3-4 时介于 394 和 3050 mm2 之间，在 L4-5 时介于 498 和 3513 mm2 之间。L3-4 (0.97, 95% CI 0.94 to 0.981) 和 L4-5 (0.99, 95% CI 0.986 to 0.995) 的组内相关系数非常好。体重和 tPMA 相关，按性别对男孩（L3-4 r = 0.90；L4-5 r = 0.90）和女孩（L3-4 r = 0.87；L4-5 r = 0.87）分层。随后开发了一个在线应用程序来轻松计算特定年龄和特定性别的 z 分数和百分位数。结论 我们为 1-16 岁的儿童提供了新的 tPMA 在椎间 L3-4 和 L4-5 水平的年龄特异性和性别特异性生长曲线。连同在线工具 (https://ahrc-apps.shinyapps.io/sarcopenia/)，