Abstract Introduction: sarcopenia is a disease characterized by reduced musculoskeletal tissue and muscle strength. The estimation of appendicular lean soft tissue by DXA (ALSTDXA) is one of the criteria for the diagnosis of sarcopenia. However, this method is expensive and not readily avaiable in clinical practice. Anthropometric equations are low-cost and able to accurate predict ALST, but such equations have not been validated for male Brazilian older adults between the ages of 60 to 79 years. To this end, this study sought to validate the existing predictive anthropometric equations for ALST, and to verify its accuracy for the diagnosis of sarcopenia in male Brazilian older adults. Methods: this cross-sectional study recruited and enrolled 25 male older adults (69.3 ± 5.60 years). ALSTDXA and anthropometric measures were determined. ALST estimations with 13 equations were compared to ALSTDXA. The validity of the equations was established when: p > 0.05 (paired t-test); standard error of the estimate (SEE) < 3.5 kg; and coefficient of determination r² > 0.70. Results: two Indian equations met the criteria (Kulkarini 1: 22.19 ± 3.41 kg; p = 0.134; r² = 0.78; EPE = 1.3 kg. Kulkarini 3: 22.14 ± 3.52 kg; p = 0.135; r² = 0.82; SEE = 1.2 kg). However, these equations presented an average bias (Bland-Altman: 0.54 and 0.48 kg) and ‘false negative’ classification for the ALST index. Thus, three explanatory equations were developed. The most accurate equation demonstrated a high level of agreement (r2adj = 0.87) and validity (r²PRESS = 0.83), a low predictive error (SEEPRESS = 1.53 kg), and an adequate ALST classification. Conclusion: anthropometric models for predicting ALST are valid alternatives for the diagnosis and monitoring of sarcopenia in older adults; however, population specificity affects predictive validity, with risks of false positive/negative misclassification.

Resumen Introducción: la sarcopenia es una enfermedad caracterizada por una reducción del tejido musculoesquelético y la fuerza muscular. Uno de los criterios utilizados para su diagnóstico es la determinación de tejido blando magro apendicular por DXA (TBMADXA), método costoso que no siempre está disponible en la práctica clínica. Las ecuaciones antropométricas suponen un bajo coste y predicen bien el TBMA, pero con una validez desconocida para los varones brasileños de 60 a 79 años. Por lo tanto, nuestro objetivo fue validar las ecuaciones antropométricas existentes predictivas del TBMA y verificar su precisión para el diagnóstico de sarcopenia en varones brasileños de edad avanzada. Métodos: participaron en este estudio transversal 25 hombres de edad avanzada (69,3 ± 5,60 años). Se determinaron el TBMADXA y las medidas antropométricas. Las ecuaciones predictivas del TBMA se compararon con el TBMADXA. La validez de las ecuaciones en las comparaciones se confirmó cuando: p > 0,05 (prueba de la “t” pareada); error estándar estimado (EEE) < 3,5 kg; coeficiente de determinación r² > 0,70. Resultados: dos ecuaciones indias cumplieron los criterios (Kulkarini 1: 22,19 ± 3,41 kg; p = 0,134; r² = 0,78; EEE = 1,3 kg. Kulkarini 3: 22,14 ± 3,52 kg; p = 0,135; r² = 0,82; EEE = 1,2 kg). Sin embargo, presentaron sesgo promedio (Bland-Altman: 0,54 y 0,48 kg) y clasificación de ‘falso negativo’ para el índice de TBMA. Por lo tanto, se crearon tres ecuaciones explicativas. La ecuación más precisa mostró un alto acuerdo (r2adj = 0,87), uma alta validez (r²PRESS = 0,83), um bajo error predictivo (EEEPRESS = 1,53 kg) y uma clasificación del TBMA adecuada. Conclusión: los modelos antropométricos para predecir el TBMA son alternativas válidas para el diagnóstico y el seguimiento de la sarcopenia en los ancianos. Pero la especificidad de la población afecta a su validez predictiva, con riesgos de incorrección por clasificación falsa positiva/negativa.

Abstract Introduction: appropriate appendicular lean soft tissue (ALST) parameters to identify sarcopenia in Brazil are scarce. The use of international references may lead to a false positive diagnosis. The objective was to propose cut-off points to identify sarcopenia in older men and women using DXA-derived ALST values from a young adult population. Methods: this was an observational study with a cross-sectional analysis. University students of both sexes (n = 125), aged 20 to 30 years, underwent anthropometric measurements and DXA scanning to obtain their ALST (kg). Cut-off points for sarcopenia were set at -2 standard deviations (-2SDs) away from the mean ALST of a young sample. Absolute values and index (ALST/height2, ALST/weight, and ALST/body mass index [BMI]) were considered as recommended by international consensus. Results: compared to women, men presented higher values of weight, height, BMI, bone mineral content, lean soft tissue, ALST, and ALST index (kg/m²). Only fat mass was higher in women, and age was not different between genders. The -2SD ALST index obtained were ≤ 6.56 kg/m² for men and ≤ 4.67 kg/m² for women. They were below international and national values, which tended to classify false positives. Conclusions: the -2SD ALST values proposed here are validated cut-offs for identifying low muscle in older adults and to prevent misdiagnosis with sarcopenia. In addition, they contribute to efficient monitoring and control of this disease in geriatric populations.

Resumen Introducción: los parámetros apropiados de masa muscular esquelética apendicular (MMEA) para identificar la sarcopenia en Brasil resultan escasos. Ello se debe al uso de referencias internacionales, lo cual puede conducir a un diagnóstico falso positivo. El objetivo del presente trabajo es proponer puntos de corte para determinar la sarcopenia en hombres y mujeres mayores empleando valores de MMEA derivados de las DXA de una población de adultos jóvenes. Métodos: estudio observacional con análisis transversal. Estudiantes universitarios de ambos sexos (n = 125), de 20 a 30 años de edad, se sometieron a mediciones antropométricas y DXA para obtener el MMEA (kg). Los puntos de corte de la sarcopenia se establecieron en -2 desviaciones estándar (-2SD) de la media de MMEA de una muestra joven. Se consideraron los valores absolutos e índices (MMEA/altura2, MMAE/peso y MMAE/índice de masa corporal [IMC]), según lo recomendado por el consenso internacional. Resultados: los hombres, en comparación con las mujeres, presentaron valores superiores de peso, altura, IMC, contenido mineral óseo, masa magra, MMEA e índice MMEA (kg/m²). Por otro lado, solo la masa grasa fue mayor en las mujeres, no habiendo diferencias de edad entre ambos géneros. El índice MMAE -2SD obtenido fue ≤ 6,56 kg/m² para los hombres y ≤ 4,67 kg/m² para las mujeres. Dichos resultados, al encontrarse por debajo de los valores internacionales y nacionales, tienden a clasificar los falsos positivos. Conclusiones: los MMAE -2SD propuestos aquí son valores de corte validados para identificar las cuantificaciones musculares bajas en los adultos mayores y para prevenir el diagnóstico erróneo de sarcopenia. Además, contribuyen a la monitorización y el control eficiente de esta enfermedad en las poblaciones geriátricas.

Abstract Introduction: currently, there is no consensus regarding accurate and low-cost methods for diagnosing lipodystrophy in people living with HIV/AIDS (PLWHA). The aim of this study was to propose anthropometric cutoff points for the diagnosis of lipodystrophy among PLWHA. Methods: we included 106 PLWHA (men = 65, women = 41) who are under antiretroviral therapy and have been clinically classified into either a “lipodystrophy” or “non-lipodystrophy” group. Anthropometric measurements included 19 regions of body perimeters and 6 skinfold thickness measures. The Youden index was used to establish anthropometric cutoff points for the diagnosis of lipodystrophy, using the mean values of the anthropometric data (referred to as “original”) along with the “Z index” (ZI) values, which were adjusted by the “Phantom Strategy.” The cutoff points were proposed when “original” anthropometric measurements and ZI values had a statistical significance of p < 0.01 and an area under the curve (AUC) higher than 70%. The size effect was assessed to verify the influence of lipodystrophy on each anthropometric measure. Results: our data analysis proposes sex-specific cutoff points for the diagnosis of lipodystrophy in PLWHA – 17 points using the “original” anthropometric measurements, and 20 using the ZI values (average effect size between 1.0 and 1.1, and AUC = 76.7% and 78%). Conclusions: our study proposes accurate cutoff points for the diagnosis of lipodystrophy using “original” anthropometric measurements and ZI values adjusted by the “Phantom Strategy.” Our findings support the use of anthropometric measurements as a simplified method for diagnosing lipodystrophy and monitoring body composition alterations in people living with HIV/AIDS.

Resumen Introducción: no existe consenso con respecto a métodos precisos y de bajo coste para diagnosticar la lipodistrofia en personas que viven con VIH/SIDA (PVVS). El objetivo de este estudio es proponer puntos de corte antropométricos para el diagnóstico de lipodistrofia entre las PVVS. Métodos: se incluyeron 106 PVVS (hombres = 65, mujeres = 41) en tratamiento antirretroviral que se clasificaron clínicamente en dos grupos de “lipodistrofia” o “no lipodistrofia”. Las mediciones antropométricas incluyeron 19 regiones de parámetros corporales y 6 medidas de pliegues cutáneos. El índice de Youden se utilizó para establecer puntos de corte antropométricos para el diagnóstico de lipodistrofia utilizando la media de los datos antropométricos (denominados “originales”) junto con los valores del “índice Z” (IZ), que fueron ajustados por la “estrategia Phantom”. Los puntos de corte se propusieron cuando las mediciones antropométricas “originales” y los valores de IZ fueron estadísticamente significativos con un valor p < 0,01 y un área bajo la curva (AUC) superior al 70%. Se evaluó el tamaño del efecto para verificar la influencia de la lipodistrofia en cada medida antropométrica. Resultados: se propusieron puntos de corte específicos según el sexo para el diagnóstico de lipodistrofia en PVVS: 17 puntos usando las medidas antropométricas “originales” y 20 usando los valores de IZ (tamaño del efecto promedio entre 1.0 y 1.1, y AUC = 76.7% y 78%). Conclusiones: se propusieron puntos de corte antropométricos para el diagnóstico de lipodistrofia. Las mediciones antropométricas son un método simplificado para diagnosticar y monitorear los cambios de composición corporal en las PVVS.

Resumo Ressonância magnética e tomografia computadorizada são referências para medir o tecido muscular (TM), porém apresentam custo elevado. A Absorciometria Radiológica de Dupla Energia (DXA) é segura, embora ainda dispendiosa, permite medir a Massa Isenta de Gordura e Osso apendicular (MIGOap), forte preditor do TM. Alternativamente, existem modelos antropométricos preditivos da MIGOap de atletas portugueses com baixo custo/risco, porém sem validação para outras populações. Objetivou-se validar modelos antropométricos portugueses preditivos da MIGOap em jovens atletas ou propor novos modelos, caso a validação falhe. A determinação da MIGOapDXA de 174 jovens atletas foi realizada por DXA. Dois modelos antropométricos (MIGOapmdJ1 e MIGOapmd2) de atletas portugueses foram testados para predizer MIGOap. Para validação o coeficiente de determinação, a diferença (viés) e a concordância entre valores medidos e preditos foram calculados. Finalmente, a associação entre média-e-diferença dos métodos foi calculada. A validação falhou, assim foram propostos novos modelos de regressão múltipla validados por estatística PRESS. Os modelos portugueses explicaram ~96% da variabilidade da MIGOapDJAf A diferença entre MIGOapmod1 e MIGOapDXA (-0,7kg) foi menor do que MI-GOapmod2 (-2,3kg), com limites de concordância de3,6 a -2,1 e de 6,1 a -1,5kg, respectivamente. Os novos modelos incluíram três equaçõespreditivaspara MIGOap. Somente MIGOapmd1foi válido, todavia mostrou grande tendência a vieses, conforme magnitude dos valores de MIGOap. Os novos modelos propostos mostraram validade com maior concordância (r2PRESS=0,98), menores erros de estimativa (EPEPRESS =0,91) e valores preditos mais homogêneos para casos extremos.

Abstract Magnetic resonance imaging and Computer tomography are gold standards in the measurement of muscle tissue (MT), but are expensive. Dual Energy X-Ray Absorptiometry (DXA) is also costly but safer and allows for the measurement of Appendicular Lean Soft Tissue (ALST), a strong predictor of MT. Alternatively, there are anthropometric models that predict the ALST of Portuguese athletes with low cost/risk that have not been validated in other populations. The aim of this study was to validate anthropometric Portuguese models that predict ALST in young athletes or, if the validation fails, to propose new models. The ALSTDXA of 174 young athletes was determined by DXA. Two anthropometric models (ALSTmod1 and ALSTmod2) measuring ALST among Portuguese athletes were tested. To validate the coefficient of determination, the difference (bias) and concordance correlation coefficient between predicted and actual values were computed. Finally, association between mean and difference of methods was verified. Validation failed and, for this reason, new multiple regression models were proposed and validated using PRESS statistics. The Portuguese models explained ~96% of the ALSTDXA variability. The difference between ALST (-0.7kg) was less than that found for the ALSTmod2 and ALSTDXA limits of agreement from 3.6 to -2.1 and from 6.1 to -1.5kg, respectively. The new models included three predictive equations for ALST. Only ASLTmod1was valid; however, it was prone to bias, depending on the magnitude of ALST values. The newly proposed models present validity with greater concordance (r2PRESS=0.98), lower standard error of estimate (SEEPRESS [kg]=0.91) and more homogeneous predicted extreme values.

Abstract Aim: to estimate the resting energy expenditure (REE) of organ tissue components using Dual Energy x-ray Absorptiometry (DXA) in pubertal boys. The mass of components and REE were compared among groups of different nutritional statuses. Methods: a sample of 278 boys (13.7 ± 2.4 years old) was grouped according to BMI nutritional status for Brazilian children and adolescents1 such as Underweight (UW), Normal weight (NW), Overweight (OW), and Obese (OB). The REE of organ tissue components given by DXA was calculated using specific models for skeletal muscle tissue (SMT), adipose tissue (AT), bone tissue (BT) and residual tissue (RT) based on previous reports. The absolute and relative REE (REEDXA) of each component were statistically compared among groups. Results: No differences of total REEDXA were found among nutritional groups (F(3, 274)=0.071, p=0.976). When, however, specific REE was considered per component, differences were found for BT and REEBT between NW-OW (p=0.003) and NW-OB (p=0.048); in AT and REEAT for all the groups (p<0.001), except between UW-NW (p=1.000); in RT and REERT between NW-OB (p=0,022) and SMT and REESMT (p=0,039). Greater proportions of organ tissue of RT and high metabolic rates, were observed in the UW group (78.3%) in comparison to the OB group (60.7%). Conclusion: This approach provides a new opportunity to examine energy metabolism for individual differences of pediatric populations. It is an applicable strategy both to prescribe exercises and to administer diets to this population, as it reveals the magnitude of heat-producing body components.