Age-specific reference values for low psoas muscle index at the L3 vertebra level in healthy populations: A multicenter study.

The progressive and generalized loss of skeletal muscle mass, strength and physical function is defined as sarcopenia. Sarcopenia is closely related to the prognosis of patients. Accurate diagnosis and adequate management of sarcopenia are crucial. The psoas muscle mass index taken at the third lumbar vertebra (L3-PMI, cm2/m2) is one of the established methods for evaluating skeletal muscle mass. However, the cutoff values of L3-PMI for diagnosis of sarcopenia are not yet to be clarified in Asian populations. We attempted to establish reference values for low L3-PMI that would be suitable for defining sarcopenia in the Northern Chinese population. This was a retrospective, multicenter cross-sectional study. A search of abdominal CT imaging reports was conducted in four representative cities in northern China. Transverse CT images were measured using the analysis software Slice-O-Matic. Low psoas muscle index was defined as the 5th percentile or mean-2SD of the study group. 1,787 healthy individuals in the study were grouped by age. The sex and number of people in each group were similar. L3-PMI had a negative linear correlation with age, and a strong correlation with the skeletal muscle index taken at the third lumbar vertebrae (L3-SMI, cm2/m2). The L3-PMI reference values in males were 5.41 cm2/m2 for 20-29 years, 4.71 cm2/m2 for 30-39 years, 4.65 cm2/m2 for 40-49 years, 4.10 cm2/m2 for 50-59 years and 3.68 cm2/m2 for over 60 years by using 5th percentile threshold. Similarly, the reference values in females were 3.32, 3.40, 3.18, 2.91, and 2.62 cm2/m2. When using mean-2SD as the reference, the values for each age group were 4.57, 4.16, 4.03, 3.37, and 2.87 cm2/m2 for males and 2.79, 2.70, 2.50, 2.30, and 2.26 cm2/m2 for females, respectively. We defined the reference values of age-specific low skeletal muscle mass when simply evaluated by L3-PMI. Further studies about the association of sarcopenia using these reference values with certain clinical outcomes or diseases are needed.

Kong M ，Lin N ，Wang L ，Geng N ，Xu M ，Li S ，Song W ，Zhou Y ，Piao Y ，Han Z ，Guo R ，Yang C ，Luo N ，Wang Z ，Xu Q ，Shi D ，Qiu W ，Li J ，Cheung EC ，Ma L ，Chen Y ，Duan Z ... -  《Frontiers in Nutrition》

Defining reference values for low skeletal muscle index at the L3 vertebra level based on computed tomography in healthy adults: A multicentre study.

Skeletal muscle mass loss is an important aspect of malnutrition and is closely related to adverse clinical outcomes. Computed tomography (CT) is the gold standard for analysing muscle mass, and the skeletal muscle index at the third lumbar vertebra (L3-SMI), measured using CT, is an important indicator to evaluate total skeletal tissue. The aims of this study were to establish reference values for low L3-SMI in Northern China, and to investigate the correlation between L3-SMI and age, and the correlation between L3-SMI and body mass index (BMI). This was a multicentre, retrospective, cross-sectional study. A search of abdominal CT imaging reports, using specific keywords, was conducted in four representative cities in northern China, from January 2016 to March 2021. Transverse CT images at the level of the third lumbar vertebra (L3) were identified, exported from the Radiology Information System, and measured using the analysis software SliceOmatic. Statistical analyses were performed using SPSS 24.0, and significance level was set at p < 0.05. Mean, standard deviations (SD) and percentiles (p5, p10, p25, p50, p75, p90, p95) were used to describe the distribution of L3-SMI in the study population. Low skeletal muscle index was defined as a 5% percentile, or two standard deviations below the mean value of younger healthy individuals (age 20-39 years). The study included 1787 healthy individuals, with a median age of 45 (25) years (range 20-88 years), and a median BMI of 23.1 (4.1) kg/m2 (range 18.5-38.7 kg/m2). Among them, 700 healthy individuals (39.1%) were aged 20-39 years. L3-SMI had a negative linear correlation with age, and a positive linear correlation with BMI. The L3-SMI reference values used to define low skeletal muscle mass loss in the Northern Chinese population, using the 5% percentile, were 40.2 cm2/m2 in men, and 31.6 cm2/m2 in women. Using the mean minus two standard deviations protocol, the reference values were 37.9 cm2/m2 and 28.6 cm2/m2 in men and women, respectively. This study analysed the human body composition of 1787 healthy people in four cities in northern China, using CT, and established diagnostic thresholds of skeletal muscle mass depletion based on 700 younger healthy adults, using the 5% percentile and mean-2SD methods. These reference values can be used to diagnose malnutrition in patients and may aide clinicians in predicting prognosis and improving nutritional therapy. Further research is warranted to determine the prognostic role of reference values against clinical outcomes in different disease populations.

Kong M ，Geng N ，Zhou Y ，Lin N ，Song W ，Xu M ，Li S ，Piao Y ，Han Z ，Guo R ，Yang C ，Luo N ，Wang Z ，Jiang M ，Wang L ，Qiu W ，Li J ，Shi D ，Li R ，Cheung EC ，Chen Y ，Duan Z ... -  《-》

Cut-off values of skeletal muscle index and psoas muscle index at L3 vertebra level by computerized tomography to assess low muscle mass.

Computerized tomography (CT) is considered the gold standard for the evaluation of total skeletal muscle quantity. Skeletal muscle assessments at the L3 vertebra level revealed significantly correlated with total body muscle measurements. Clinicians need cut-offs to evaluate low muscle mass in various patients who already had CT imaging without any additional cost. This assessment is important to help the physicians to stratify the patients for mortality and other complications. It may also enable the diagnosis of malnutrition by the GLIM criteria. Few studies reported cut-offs in different populations. We aimed to provide cut-off values for total skeletal muscle index (SMI) and psoas muscle mass index (PMI) at the L3 vertebra level in the Turkish population. We assessed the preoperative plain CT images of living adult liver donors who were admitted to a single transplantation center between June 2010 and April 2018. We derived cut-off values with two alternative methods, the 5th percentile value or mean minus two standard deviations and from two groups of study participants, i.e. the total study population and the younger subgroup aged between 18 and 40. The study population involved 601 subjects with a mean age of 32.5 ± 9 (range: 18-59 years) and 326 (54.2%) was male. The younger subgroup was composed of 482 individuals with a mean age of 28.8 ± 5.9 and 55.6% male. In patients aged between 18 and 40, PMI and SMI cut-offs by using the 5th percentile were 5.40 cm2/m2, 41.42 cm2/m2 for males; and 3.56 cm2/m2, 30.70 cm2/m2 for females; respectively. The cut-offs of PMI and SMI by using mean minus two standard deviations were 4.62 cm2/m2, 38.67 cm2/m2 for males; and 2.66 cm2/m2, 27.8 cm2/m2 for females; respectively. These cut-offs were comparable to the other populations. Our study provided cut-offs to be used in CT images for PMI and SMI. There is a need for further longitudinal studies to verify whether these cut-offs are successful in predicting mortality or other adverse outcomes associated with low muscle mass.

Bahat G ，Turkmen BO ，Aliyev S ，Catikkas NM ，Bakir B ，Karan MA ... -  《-》

Psoas muscle index is not representative of skeletal muscle index for evaluating cancer sarcopenia.

A common method for diagnosing sarcopenia involves estimating the muscle mass by computed tomography (CT) via measurements of the cross-sectional muscle area (CSMA) of all muscles at the third lumbar vertebra (L3) level. Recently, single-muscle measurements of the psoas major muscle at L3 have emerged as a surrogate for sarcopenia detection, but its reliability and accuracy remain to be demonstrated. This prospective cross-sectional study involved 29 healthcare establishments and recruited patients with metastatic cancers. The correlation between skeletal muscle index (SMI = CSMA of all muscles at L3/height2 , cm2 /m2 ) and psoas muscle index (PMI = CSMA of psoas at L3/height2 , cm2 /m2 ) was determined (Pearson's r). ROC curves were prepared based on SMI data from a development population (n = 488) to estimate suitable PMI thresholds. International low SMI cut-offs according to gender were studied for males (<55cm2 /m2 ) and for females (<39 cm2 /m2 ). Youden's index (J) and Cohen's kappa (κ) were calculated to estimate the test's accuracy and reliability. PMI cut-offs were validated in a validation population (n = 243) by estimating the percentage concordance of sarcopenia diagnoses with the SMI thresholds. Seven hundred and sixty-six patients were analysed (mean age 65.0 ± 11.8 years, 50.1% female). Low SMI prevalence was 69.1%. Correlation between the SMI and PMI for the entire population was 0.69 (n = 731, P < 0.01). PMI cut-offs for sarcopenia were estimated in the development population at <6.6cm2 /m2 in males and at <4.8 cm2 /m2 for females. The J and κ coefficients for PMI diagnostic tests were weak. The PMI cut-offs were tested in the validation population where 33.3% of the PMI measurements were dichotomously discordant. A diagnostic test employing single-muscle measurements of the psoas major muscle as a surrogate for sarcopenia detection was evaluated but found to be unreliable. The CSMA of all muscles must be considered for evaluating cancer sarcopenia at L3.

Pigneur F ，Di Palma M ，Raynard B ，Guibal A ，Cohen F ，Daidj N ，Aziza R ，El Hajjam M ，Louis G ，Goldwasser F ，Deluche E ... -  《-》

Relative muscle indices and healthy reference values for sarcopenia assessment using T10 through L5 computed tomography skeletal muscle area.

Derstine BA ，Holcombe SA ，Wang NC ，Ross BE ，Sullivan JA ，Wang SC ，Su GL ... -  《Scientific Reports》