External validation of BIA equations to estimate appendicular skeletal muscle mass in older adults: Importance of the bias analysis and derivation of correction factors to achieve agreement.

There are several equations based on bioelectrical impedance analysis (BIA) to estimate with high precision appendicular skeletal muscle mass (ASM). However, most of the external validation studies have reported that these equations are inaccurate or biased when applied to different populations. Furthermore, none of the published studies has derived correction factors (CFs) in samples of community-dwelling older adults, and none of the published studies have assessed the influence of the dual-energy X-ray absorptiometry (DXA) model on the validation process. This study assessed the agreement between six BIA equations and DXA to estimate ASM in non-Caucasian older adults considering the DXA model and proposed a CF for three of them. This analysis included 547 non-institutionalized subjects over 60 years old from the northwest of Mexico who were physically independent and without cognitive impairment: 192 subjects were measured using DXA Hologic, while 355 were measured by DXA Lunar. The agreement between each of the equations and DXA was tested considering the DXA model used as a reference method for the design of each equation, using the Bland and Altman procedure, a paired t test, and simple linear regression as objective tests. This process was supported by the differences reported in the literature and confirmed in a subsample of 70 subjects measured with both models. Only six published BIA equations were included. The results showed that four equations overestimated ASMDXA, and two underestimated it (p < 0.001, 95% CI for Kim's equation:-5.86--5.45, Toselli's:-0.51--0.15, Kyle's: 1.43-1.84, Rangel-Peniche's: 0.32-0.74, Sergi's: 0.83-1.23, and Yoshida's: 4.16-4.63 kg). However, Toselli's, Kyle's and Rangel-Peniche's equations were the only ones that complied with having a homogeneous bias. This finding allowed the derivation of CFs, which consisted of subtracting or adding the mean of the differences from the original equation. After estimating ASM applying the respective CF, the new ASM estimations showed no significant bias and its distribution remained homogeneously distributed. Therefore, agreement with DXA in the sample of non-Caucasian was achieved. Adding valid CFs to some BIA equations allowed to reduce the bias of some equations, making them valid to estimate the mean values of ASM at group level.

Differences in Body Composition in Older People from Two Regions of Mexico: Implications for Diagnoses of Sarcopenia and Sarcopenic Obesity.

BACKGROUND: Mexico is a country that is rich in ethnicity and cultural diversity, divided into three well-defined socioeconomic, ecological, and epidemiological areas. However, we do not know the influence that these factors may have on body composition. Therefore, this study was designed to assess body composition and compare appendicular skeletal muscle mass (ASM) in older people from two areas of the country. METHODS: This is a cross-sectional study that included 430 subjects ≥60 years of age from northwestern and central Mexico. Body composition, including ASM, was measured by dual-energy X-ray absorptiometry, while anthropometry, handgrip strength, demographic variables, health status/chronic conditions, and energy expenditure data were all included. RESULTS: Men and women from the northwestern region had 5.9 kg and 3.8 kg more body fat, respectively, and 3.9 kg more as a group than their counterparts from central Mexico (p ≤ 0.0001). While there were no significant differences across gender or region in terms of ASM, the older subjects from central Mexico had a significantly higher ASM index (ASMI) than the sample from the northwest. When ASM was adjusted for age, body weight, height, health status/chronic conditions, estimated energy expenditure, and demographic variables, the subjects from central Mexico had significantly higher adjusted mean values of ASM and ASMI than their counterparts from the northwest. CONCLUSION: Older people from two regions of Mexico had significantly different estimates of body composition. Our findings highlight the importance of regionalizing estimates of ASM and ASMI if they are to be used for diagnostic purposes. It is also important to emphasize that appendicular skeletal muscle mass, or the ASM index, should be adjusted for other associated biological variables.

[Not Available]. / Composición corporal de niños de entre 8 y 10 años de edad, con y sin antecedente de bajo peso al nacer, residentes en el estado de Querétaro, México.

Introducción: el bajo peso al nacer (BPN) es un factor de riesgo para desarrollar obesidad en la vida adulta.Objetivo: evaluar diferencias en la composición corporal de niños de entre 8 y 10 años de edad con y sin antecedente de BPN.Métodos: fue un estudio observacional, transversal comparativo. Participaron 112 niños (95 con adecuado peso al nacer [APN] y 17 con BPN). Se realizó antropometría (peso, talla, circunferencias de cintura y cadera, pliegue cutáneo de tríceps [PCT] y subescapular [PCSE]).Resultados: se encontró una prevalencia combinada del 41% para sobrepeso y obesidad en ambos grupos de estudio. El porcentaje de grasa corporal total fue menor en las niñas con BPN (no significativo); sin embargo, el indicador PCT-PCSE fue significativamente más alto (p = 0,04) que el de las niñas con APN. En contra de lo esperado, al estratificar según porcentaje de grasa y peso al nacer, se encontró que el grupo con BPN presentó un porcentaje de grasa bajo (p < 0,05) en comparación con el grupo de APN, siendo 6 veces mayor la posibilidad de que un niño con BPN presente porcentaje de grasa total bajo a esta edad.Conclusiones: a estas edades no se encontró mayor porcentaje de grasa en el grupo con BPN en comparación con el de APN; sin embargo, las niñas con BPN presentaron mayor deposición de grasa troncal que las de APN. La deposición de grasa es un indicador que hay que considerar, y no únicamente el índice de masa corporal, en la evaluación nutricia infantil.

[Dietary training for school food service providers in support of the Acuerdo Nacional para la Salud Alimentaria]. / Capacitación alimentaria a comodatarios en apoyo al Acuerdo Nacional para la Salud Alimentaria.

BACKGROUND: To address the problem of overweight and obesity in Mexico, in 2010 the Acuerdo Nacional para la Salud Alimentaria was published. At school level, food service providers were considered essential to comply with certain commitments. The goal of this intervention was to train school food service providers in school eating establishments (SEE) as to the criteria in the general guidelines for the sale and distribution of food in schools of basic education. METHODS: 13 SEE in San Luis Potosi participated. Based on an initial diagnosis, a class-workshop of 5 sessions was designed. Knowledge regarding food was evaluated at the beginning and end of the sessions. The percentage of adherence regarding general hygiene and food preparation and distribution was obtained at the beginning, one month, and two months post-intervention. RESULTS: School food service providers had little knowledge on the objectives of the Acuerdo in food groups and combination, as well as reading labels; there were significant changes in the last two after intervention. The initial percentage of overall hygiene compliance was 60 %, with an increase of almost 20 % post-training. The preparation and distribution of food did not show significant changes. CONCLUSIONS: School food service providers acquired knowledge about the guidelines that a SEE comply with, without putting them into practice, given the economic impact that it implies.

Introducción: en apoyo a la problemática de sobrepeso y obesidad en México, en el 2010 se publicó el Acuerdo Nacional para la Salud Alimentaria. A nivel escolar, los comodatarios se consideraron fundamentales para cumplir con ciertos compromisos. El objetivo de esta intervención fue capacitar a comodatarios de los Establecimientos de Consumo Escolar (ECE) en cuanto a los criterios establecidos en los "Lineamientos Generales para el Expendio y Distribución de Alimentos en Planteles de Educación Básica." Métodos: participaron 13 ECE en San Luis Potosí. Con base en un diagnóstico inicial, se diseñó un curso-taller de 5 sesiones. Se evaluaron conocimientos en materia alimentaria al inicio y al final de las sesiones. Se obtuvo el porcentaje de apego en cuanto a higiene general, preparación y distribución de alimentos, al inicio, al mes y a los dos meses postintervención. Resultados: los comodatarios presentaron pocos conocimientos en los objetivos que persigue el "Acuerdo" en grupos y combinación de alimentos así como en lectura de etiquetas; con cambios significativos en los dos últimos tras la intervención. El porcentaje inicial de cumplimiento en higiene general fue del 60 %, con un incremento de casi 20 % postcapacitación. La preparación y distribución de alimentos no presentaron cambios significativos. Conclusiones: los comodatarios adquirieron conocimientos sobre los lineamientos que debe cubrir un ECE, sin ponerlos en práctica, dado el impacto que ello implica en su economía.

Accuracy of a predictive bioelectrical impedance analysis equation for estimating appendicular skeletal muscle mass in a non-Caucasian sample of older people.

OBJECTIVE: To design and validate a predictive BIA equation to estimate ASM in a sample of non-Caucasian older people and to explore the accuracy of two previous single-frequency BIA published equations. METHOD: This is a cross-sectional study in 213 physically-independent and apparently healthy older men and women subjects from a central region of Mexico. Dual-energy X-ray absorptiometry, anthropometry, resistance, reactance, and other independent predictive variables were assessed. The total sample was randomized and split into two sub-samples: one group for the development of the predictive single-frequency BIA equation and the other for its validation. The equation was derived by step-wise regression, the goodness of fit was assessed by the highest determination coefficient (R(2)) and precision by the lowest root mean square error. In the validation sample, the accuracy of the new and the published BIA equations was tested by pure error. In addition, Bland and Altman analysis tested the bias. RESULTS: The selected model had a R(2) of 0.91 and a RMSE of 1.01 kg and fulfilled every regression assumption. The predictive variables included were: Ht(2)/R, sex, and body weight. The new BIA equation showed a PE close to RMSE of the estimate with no significant bias. The published BIA equations proved to be inaccurate and had significant bias. CONCLUSIONS: This new single-frequency BIA-derived equation was precise, accurate and free of bias. Published BIA equations to estimate ASM should not be used indistinctly in other ethnic groups without validation.