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.

Sarcopenia: Influence of Regional Skeletal Muscle Cutoff Points and Fat-Free Mass in Older Mexican People-A Pilot Study.

BACKGROUND: Variation in the prevalence of sarcopenia is related to the skeletal muscle index cutoff points applied. The objective of this pilot study was to examine the recruitment process for testing different sarcopenia definitions (ASMI cutoffs) in older Mexican adults. It explored whether the prevalence of sarcopenia decreased by applying ethnic- and gender-specific, DXA-derived appendicular skeletal muscle index (ASMI)-cutoff points in the definitions, as well as some associated factors in a sample of community-dwelling older Mexican people. METHODS: This is a pilot feasibility study that included a convenience sample of 217 community-dwelling older adults. Volunteers underwent DXA measurements and an assessment of functional status based on hand grip strength and physical performance. Six definitions were formed based on the 2010 EWGSOP criteria, but using different cutoff points for each of the three components, including regional cutoff points for ASMI derived from young Mexican adults. Several risk factors for sarcopenia were also assessed. RESULTS: The prevalence of sarcopenia varied according to the different definitions applied. The lowest level was found with the definition that applied regional ASMI-cutoff points (p < 0.01). The sarcopenic older adults had significant lower body weight, fat mass, and fat-free mass (FFM) than the nonsarcopenic subjects. The risk of sarcopenia increased with age and low FFM (p < 0.001). CONCLUSION: The present study demonstrates the feasibility of the main study, and our data support the notion that using regional ASMI cutoff points resulted in a low prevalence of sarcopenia. Therefore, it is preferable to estimate the prevalence of this condition using ethnic- and gender-specific cutoff points and to explore associated factors such as low FFM.

Riesgo de desnutrición y factores asociados en una muestra de adultos mayores en la comunidad e institucionalizados de Yucatán, México / Malnutrition risk and associated factors in a sample of older adults in the community and institutionalized in Yucatan, Mexico

Evaluar la prevalencia de riesgo de desnutrición (RD) en adultos mayores de dos municipios de Yucatán, México, e identificar algunos factores asociados. Estudio transversal con muestreo intencional no probabilístico en 6 centros de atención geriátrica, una clínica universitaria y visitas domiciliares. Noventa y seis adultos mayores de 60 años (76% mujeres), 42 residentes de estancias geriátricas y 54 no institucionalizados. Se evaluó el RD con la escala de Valoración Mínima del Estado de Nutrición (VMEN), junto con variables demográficas, de funcionalidad, comorbilidades, depresión y apetito. La composición corporal se evaluó con ecuaciones basadas en antropometría e impedancia bioeléctrica. Se realizaron análisis descriptivos, t de Student, Kolmogorov-Smirnov, chi cuadrado, análisis univariado y análisis de regresión múltiple. El 47,9 % (46 sujetos; 37 mujeres y 9 varones) presentaron RD de acuerdo con la VMEN y 52,1% de los participantes fueron clasificados con estado nutricio normal de acuerdo con dicha escala. Los valores promedio de la masa corporal libre de grasa y la masa muscular esquelética en extremidades de sujetos con RD, fueron más bajos que en aquellos con estado de nutrición normal (p< 0,05). El análisis de regresión logístico múltiple ajustado por género indicó que la edad (OR=1,08, p=0,005) y la depresión (OR=3,79, p=0,017) fueron factores predictores asociados con RD. El 47,9 % de los participantes presentaron RD. Se requieren acciones para diagnosticar y atender el RD y evitar que progrese a desnutrición. La edad y la depresión se debieran incluir como posibles marcadores tempranos de desnutrición en futuros estudios poblacionales e intervenciones nutricionales en adultos mayores en comunidad e institucionalizados en Yucatán(AU)

To assess the prevalence of Malnutrition Risk (MR) in older adults from two municipalities of Yucatan, Mexico, and to identify some associated factors. Cross-sectional study, using non-probabilistic sample in six geriatric care centers, a university clinic, and home visits. Ninety-six adults over 60 years (76% women), 42 residents of geriatric care homes, and 54 non-institutionalized. The MR was assessed by the Mini Nutritional Assessment scale (MNA), along with demographic, functionality, comorbidities, depression, and appetite variables. Body composition was also assessed by bioelectrical impedance analysis. Descriptive analyzes, Student's t, Kolmogorov-Smirnov, chi-square, univariate, and multiple regression analysis were performed. Of the total sample, 47.9% (46 subjects; 37 women and 9 men) presented RD according to the VMEN and 52.1% of the participants were classified with normal nutritional status according to the scale. Mean values of fat-free mass and appendicular skeletal muscle mass were lower in subjects with MR than in those with normal nutritional status (p <0.05). The multiple logistic regression analysis adjusted by gender indicated that age (OR = 1.08, p = 0.005) and depression (OR = 3.79, p = 0.017) were predictor associated factors with MR. Almost forty eight percent of the participants present MR. Actions are required to diagnose and treat MR, avoiding progressing to malnutrition. Age and depression should be included as possible early markers of malnutrition in future population studies and nutritional interventions, in the community and institutionalized older adults in Yucatan(AU)

The fat mass index, not the fat-free mass index, is associated with impaired physical performance in older adult subjects: Evidence from a cross-sectional study.

BACKGROUND: Impaired physical performance (IPP) and physical disability (PD) are two serious public health problems in older adult populations worldwide. While studies show that changes in body composition are important risk factors for developing these conditions, there is little evidence that the fat-free mass (FFM) and fat mass (FM) indices (FFMI and FMI, respectively) are associated with IPP in older men and women. This study assessed the association among FFMI, FMI, and IPP using Short Physical Performance Battery (SPPB) in Mexican men and women aged over 60 years. METHODS: This cross-sectional study included 217 older people (men 34.6%, women 65.4%; 60-92 years). FFM and FM were assessed by dual X-ray absorptiometry, assuming a two-compartment model. FFM and FM were adjusted by height squared and the indices were obtained. After assessment of physical performance by SPPB, subjects with scores ≤6 were classified as having IPP. Associations were tested by multiple logistic regression analysis in separated models. RESULTS: IPP prevalence was 14.3%. Women were affected more than men. Regression analysis showed no significant association between FFMI and IPP, but FMI was strongly-associated, as for each unit increase in FMI, the risk of IPP rose significantly (OR: 1.14), and this result remained significant after adjusting for age, comorbidity, polypharmacy, and the appendicular skeletal muscle mass index (OR: 1.23; p ≤ 0.001). These results emphasize the importance of preventing increases in FM and avoiding overweight and obesity in older men and women.

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.