Ultrasound for measurement of skeletal muscle mass quantity and muscle composition/architecture in critically ill patients: A scoping review on studies' aims, methods, and findings.

AIMS: This scoping review aimed to identify, explore, and map the objectives, methodological aspects, and results of studies that used ultrasound (US) to assess skeletal muscle (SM) in critically ill patients. METHODS: A scoping review was conducted according to the Joanna Briggs Institute's methodology. All studies that evaluated SM parameters from the US in patients admitted to the intensive care unit (ICU) were considered eligible. We categorized muscle thickness and cross-sectional area as parameters for assessing SM quantity, while echogenicity, fascicle length, and pennation angle analysis were used to evaluate muscle "quality" (composition/architecture). A literature search was conducted using four databases for articles published until December 2022. Independent reviewers selected the studies and extracted data. Descriptive statistics were calculated to present the results. RESULTS: A total of 107 studies were included, the majority of which were prospective cohort studies (59.8 %) conducted in general ICUs (49.5 %). The most frequent objective of the studies was to evaluate SM quantity depletion during the ICU stay (25.2 %), followed by determining whether a specific intervention would modify SM (21.5 %). Most studies performed serial SM evaluations (76.1 %). The rectus femoris muscle thickness was evaluated in most studies (67.9 %), followed by the rectus femoris cross-sectional area (54.3 %) and the vastus intermedius muscle thickness (40.2 %). The studies demonstrated the feasibility and reproducibility of US for SM evaluation, especially related to quantitative parameters. Most studies (70.3 %) reported significant SM quantity depletion during hospitalization. However, the accuracy of the US in measuring SM varied across the studies. CONCLUSIONS: The lack of detailed description and standardization in the protocols adopted by the studies included in this scoping review precludes the translation of the evidence related to US for SM assessment into clinical practice.

Applicability of the SARC-F questionnaire by remote interview.

OBJECTIVE: The aim of this study was to assess the applicability of the strength, assistance with walking, rising from a chair, climbing stairs, and falls (SARC-F) questionnaire by telephone to identify sarcopenia risk (SR; SARC-F ≥6) and low muscle function risk (LMFR; SARC-F ≥ 4) and their associated risk factors in a cohort of community-dwelling older adults in southern Brazil. METHODS: A longitudinal study was carried out with community-dwelling older individuals from COMO VAI? STUDY: Sociodemographic, behavioral, and health-related information were collected at baseline, and, in the second assessment, the SARC-F questionnaire was applied by phone or in-person interviews. Older adults identified with sarcopenia at the baseline assessment were excluded. Adjusted analysis by Poisson regression according to hierarchical levels was performed. RESULTS: Of the 1451 participants interviewed at baseline, only 951 participated in the second assessment. During the second assessment, 732 adults (77%) were interviewed by phone and 219 (23%) in person. There was no statistically significant difference for the SR (9.1 versus 9.7%, P = 0.802) and LMFR (22.4 versus 20.0%, P = 0.435) prevalence when the SARC-F questionnaire was administered in person or by phone, respectively. Age ≥80 y, presence of depressive symptoms, multimorbidity, dependence to perform one or more daily activities, and polypharmacy were factors associated with a higher risk for poor outcomes in older adults interviewed by phone. CONCLUSIONS: The similar prevalence between in-person and remote assessments suggests the feasibility of using the SARC-F questionnaire by phone interview as a reliable alternative for sarcopenia and low muscle function risk assessment without the requirement of face-to-face evaluations.

Calf circumference: cutoff values from the NHANES 1999-2006.

BACKGROUND: Calf circumference (CC) is used in geriatric studies as a simple and practical skeletal muscle (SM) marker for diagnosing low SM and sarcopenia. Currently applied CC cutoff points were developed in samples including older participants; values representative of the full adult lifespan are lacking. OBJECTIVES: We aimed to develop CC cutoff points and to identify relevant confounding factors from the large and diverse NHANES 1999-2006 population sample. METHODS: Demographic, anthropometric, and imaging data (DXA, appendicular lean mass) from the adult (age ≥18 y) NHANES sample were partitioned into subgroups according to sex, age, ethnicity, and race. Adults aged 18-39 y and BMI (in kg/m2) 18.5-24.9 were set as a reference population; CC cutoff points were derived at 1 and 2 SDs below the mean. RESULTS: The sample included 17,789 participants, 51.3% males and 48.7% females, with respective ages (mean ± SD) of 43.3 ± 16.1 y and 45.5 ± 16.9 y. CC was strongly correlated with appendicular lean mass, r = 0.84 and 0.86 for males and females (both P < 0.001), respectively. Significant differences in mean CC were present across sex, ethnic, self-reported race, and BMI groups. Adjusting CC for adiposity using BMI revealed a decrease in CC beginning after the second decade in males and third decade in females. Rounded CC cutoff values for moderately and severely low CC were 34 cm and 32 cm (males), and 33 cm and 31 cm (females), respectively. Our findings support the use of BMI-adjusted CC values for participants outside the normal-weight BMI range (18-24.9). CONCLUSIONS: This study defined CC values in a diverse population sample along with a BMI-adjustment approach that helps to remove the confounding effects of adiposity and thereby improves CC as a useful clinical estimate of SM mass.

2 + 2 (+ 2) = 4: A new approach for appendicular muscle mass assessment by ultrasound.

OBJECTIVE: The aim of this study was to develop new appendicular lean mass (ALM) prediction models based on ultrasound and anthropometric measurements. METHODS: This was a cross-sectional assessment of a subsample from a population-based study (COMO VAI?), conducted with community-dwelling individuals ≥60 y of age living in a southern Brazilian city. ALM was measured by dual-energy x-ray absorptiometry (DXA). Muscle thickness (MT) from supine participants was assessed by ultrasound on the anterior aspect of both upper and lower limbs. Such measures, along with anthropometric data, were used to develop prediction models (multivariable linear regression) through the backward stepwise method. RESULTS: The study included 190 participants composed mainly of women, white, and middle-class individuals. The best ALM predictive performance was achieved by a model based on two "lengths" (height and arm length), two circumferences (dominant arm and thigh), and two ultrasound-measured MTs (dominant arm and thigh): R2 = 0.90, limits of agreement: ±2.36 kg. Closely satisfactory results were also achieved by an "abbreviated" model composed by the two aforementioned "lengths" and MTs (R2 = 0.89, limits of agreement: ±2.51 kg). ALM estimates from both equations were unbiased and similar to DXA measurements (P = 0.13 and 0.09, respectively). Bootstrap analysis favorably suggested the validity of the models. CONCLUSIONS: Based on two ultrasound assessments and a few anthropometric measurements, the developed equations produced accurate and unbiased ALM estimates in the sample. Hence: 2 MTs + 2 lengths (+ 2 circumferences) = 4 limbs' muscle mass. Such models might represent promising alternatives for muscle assessment among older individuals.

Accuracy of SARC-F and SARC-CalF for sarcopenia screening in older women from southern Brazil.

OBJECTIVES: The aim of this study was to verify the accuracy of the SARC-F and the SARC-CalF as screening tools for sarcopenia in community-dwelling older women ≥60 y of age. METHODS: This was a cross-sectional study evaluating a convenience sample of women ≥60 y of age, living in Southern Brazil. Sarcopenia was defined according to the criteria proposed in the latest European Working Group on Sarcopenia in Older People consensus (EWGSOP2). Appendicular muscle mass was assessed by dual-energy x-ray absorptiometry. Muscle strength was measured by handheld dynamometry, and physical performance through the 4-m gait speed test. The SARC-F questionnaire and SARC-CalF score for sarcopenia screening were also applied. RESULTS: We evaluated 288 participants, with a mean age of 67.6 ± 5.8 y. The frequency of probable and confirmed sarcopenia in the sample was 7.3% and 2.1%, respectively. The frequency of risk for sarcopenia assessed by the SARC-F was 4.5% and SARC-CalF 22.2%. Despite the excellent specificity (95.4%) demonstrated by the SARC-F, its sensitivity in identifying confirmed cases was null, whereas the SARC-CalF showed high sensitivity (83.3%) and good specificity (79%). CONCLUSION: The present study findings suggested that SARC-CalF may be able to outperform SARC-F as a sarcopenia screening tool in women ≥60 y of age even under the new EWGSOP2 criteria, the main determinant of which is strength as observed in studies based on the previous definition.

Prevalence of Sarcopenic Obesity Using Different Definitions and the Relationship With Strength and Physical Performance in the Canadian Longitudinal Study of Aging.

Sarcopenic obesity is associated with several negative health outcomes. However, the prevalence of this condition - and the relationship to physical performance parameters - varies across definitions. The aim of this cross-sectional investigation was to describe the prevalence of sarcopenic obesity using different published definitions and their relationship with handgrip strength and walking speed in older Canadian adults. Individuals aged 65+ in the Canadian Longitudinal Study on Aging (n = 11,803; 49.6% male, 50.4% female) were included. Body composition was measured using dual X-ray absorptiometry. Sarcopenic obesity was defined using 29 definitions. Low handgrip strength was identified as < 27 kg in males and < 16 kg in females and poor physical performance was defined as gait speed ≤ 0.8 m/s. The prevalence of sarcopenic obesity ranged from 0.1 to 85.3% in males, and from 0 to 80.4% in females. Sarcopenic obesity was frequently associated with low handgrip strength (p < 0.05) in both males (14/17 definitions, 82.4%) and females (21/29 definitions, 72.4%). In very few definitions, sarcopenic obesity was associated with slow gait speed (males: 1/17 definitions [6.7%]; females: 2/29 [6.9%]). In conclusion, the prevalence of sarcopenic obesity varied greatly according to definitions and sarcopenic obesity was frequently associated with low handgrip strength.

Think Globally, Act Locally: The Importance of Population-Specific Bioelectrical Impedance Analysis Prediction Equations for Muscle Mass Assessment.

BACKGROUND: Bioelectrical impedance analysis (BIA) is a convenient muscle assessment method, but its accuracy highly depends on population-specific aspects of the adopted equation. We aimed to develop appendicular lean mass (ALM) prediction models for older South Americans and to compare their performances to those of reference equations in the same sample. METHODS: Cross-sectional evaluation of 192 community-dwelling Brazilian subjects ≥60 years old from the COMO VAI? STUDY: Using measurements from single-frequency and multifrequency devices (BIASF and BIAMF, respectively), new ALM prediction equations were developed (reference method: dual-energy x-ray absorptiometry [DXA]). Validity was assessed by bootstrapping. Four previously established equations were also tested, and the performances were compared using Bland-Altman analysis. RESULTS: Stepwise variable selection produced the following equations: ALMSF-BIA = (2.08 × sex) + (0.04 × weight) + (0.24 × RI50 ) + (0.07 × Xc50 ) - 0.16; ALMMF-BIA = (1.85 × sex) + (0.03 × weight) + (0.31 × RI50 ) + (0.04 × Xc50 ) + (0.01 × Z5 ) - 8.16, where ALM is estimated in kg; female sex = 0 and male sex = 1; weight is measured in kg; RI50 is the resistance index at 50 kHz measured in cm2 /Ω); Xc50 is the reactance at 50 kHz measured in Ω; and Z5 is impedance at 5 kHz measured in Ω. The equations explained, respectively, 89% and 90% of the variability of ALMDXA in our sample, and their estimates were not significantly different from DXA measurements. Bland-Altman analysis revealed accurate and unbiased performances for both models, with similar limits of agreement (BIASF : ±2.58 kg; BIAMF : ±2.48 kg), and their validity was considered adequate by the bootstrap method. The reference equations, however, systematically overestimated ALM in our sample. CONCLUSION: The proposed equations might represent practical options to estimate ALM in older noninstitutionalized South Americans. Further external validation, though, is required to verify the reproducibility of our findings.

New Prediction Equations to Estimate Appendicular Skeletal Muscle Mass Using Calf Circumference: Results From NHANES 1999-2006.

BACKGROUND: Low appendicular skeletal muscle mass (ASM) is associated with negative outcomes, but its assessment requires proper limb muscle evaluation. We aimed to verify how anthropometric circumferences are correlated to ASM and to develop new prediction equations based on calf circumference and other anthropometric measures, using dual-energy X-ray absorptiometry (DEXA) as the reference method. METHODS: DEXA and anthropometric information from 15,293 adults surveyed in the 1999-2006 NHANES were evaluated. ASM was defined by the sum of the lean soft tissue from the limbs. Anthropometric data included BMI and calf, arm, thigh, and waist circumferences. Correlations were assessed by Pearson's correlation, and multivariable linear regression produced 4 different ASM prediction equations. The concordance and the overall 95% limits of agreement between measured and estimated ASM were assessed using Lin's coefficient and Bland-Altman's approach. RESULTS: Calf and thigh circumferences were highly correlated with ASM, independent of age and ethnicity. Among the models, the best performance came from the equation constituted solely by calf circumference, sex, race, and age as independent variables, which was able to explain almost 90% of the DEXA-measured ASM variation. The inclusion of different anthropometric parameters in the model increased collinearity without improving estimates. Concordance between the four developed equations and DEXA-measured ASM was high (Lin's concordance coefficient >0.90). CONCLUSION: Despite the good performance of the four developed equations in predicting ASM, the best results came from the equation constituted only by calf circumference, sex, race, and age. This equation allows satisfactory ASM estimation from a single anthropometric measurement.

Sarcopenia in Brazilian rural and urban elderly women: Is there any difference?

OBJECTIVES: There are many studies concerning sarcopenia prevalence from all over the world. However, to our knowledge, only two compared urban and rural sarcopenia and to date, none have been conducted in the Americas. The aim of this study was to evaluate the prevalence of sarcopenia in a convenience sample of women ≥60 y of age who underwent bone densitometry and live in urban and rural areas of southern Brazil. METHODS: This was a cross-sectional study comprising 205 women ≥60 y of age who had undergone bone densitometry. Sarcopenia was defined according to the criteria recommended by the European Working Group on Sarcopenia in Older People. The diagnosis combined the evaluation of muscle mass (assessed by dual-energy x-ray absorptiometry), muscle strength (measured using a manual digital dynamometer), and muscular performance (evaluated by the 4-m walking speed test). Sociodemographic data, smoking status, chronic conditions, number of falls and fractures in the past year, and level of physical activity also were collected. RESULTS: Sarcopenia was present in 2.4% of the total sample. Urban and rural populations significantly differed in terms of schooling (P < 0.001), occupation (P = 0.010), socioeconomic status (P = 0.001), and smoking status (P = 0.006). The environment in which the women lived was independently associated with sarcopenia (odds ratio, 9.561; 95% confidence interval, 1.021-89.523; P = 0.048). The prevalence of sarcopenia was significantly higher in the urban women than in the rural group (5.7 versus 0.7%, respectively; P = 0.047). After multivariate analysis, the environment of the women's residence remained independently associated with sarcopenia. CONCLUSION: Urban elderly women are more vulnerable to sarcopenia than rural elderly women.

Bioelectrical impedance analysis in the assessment of sarcopenia.

PURPOSE OF REVIEW: Bioelectrical impedance analysis (BIA) is an accepted technique to estimate low muscle mass for sarcopenia diagnosis. However, muscularity assessment from BIA relies on prediction equations, estimating different compartments according to the calibration method. Low muscle mass can be defined using different approaches. RECENT FINDINGS: There is a lack of standardization on how low muscularity is defined in the context of sarcopenia. Recent studies have shown discrepant results for the estimation of low muscle mass when different prediction equations are used in the same BIA device. Different sarcopenia prevalence rates are observed if different definitions are used to identify low muscle mass. Most of the studies using BIA for diagnosing sarcopenia use the incorrect combination of specific population cut-off or a different device from the original equation. SUMMARY: The lack of standardization of BIA use for assessing muscularity results in a wide range of sarcopenia prevalence rates among studies, even when conducted in the same population. As BIA equations and cut-off values are population and device-specific, results should be interpreted with caution when data from different devices are applied in equations or using cut-off values from a different population.

Falls among older adults in the South of Brazil: prevalence and determinants.

OBJECTIVE Evaluate the prevalence and the factors associated with the occurrence of falls among older adults. METHODS A cross-sectional study with a representative sample of 1,451 elderly residents in the urban area of Pelotas, RS, in 2014. A descriptive analysis of the data was performed and the prevalence of falls in the last year was presented. The analysis of demographic, socioeconomic, behavioral and health factors associated with the outcome was performed using Poisson regression with adjustment for robust variance according to the hierarchical model. The variables were adjusted to each other within each level and for the higher level. Those with p ≤ 0.20 were maintained in the model for confounding control and those with p < 0.05 were considered to be associated with the outcome. RESULTS The prevalence of falls among older adults in the last year was 28.1% (95%CI 25.9-30.5), and most occurred in the person's own residence. Among the older adults who fell, 51.5% (95%CI 46.6-56.4) had a single fall and 12.1% (95%CI 8.9-15.3) had a fracture as a consequence, usually in the lower limbs. The prevalence of falls was higher in women, adults of advanced age, with lower income and schooling level, with functional incapacity for instrumental activities, and patients with diseases such as diabetes, heart disease, and arthritis. CONCLUSIONS The occurrence of falls reached almost a third of the older adults, and the prevalence was higher in specific segments of the population in question. About 12% of the older adults who fell fractured some bone. The factors associated with the occurrence of falls identified in this study may guide measures aimed at prevention in the older adult population.

Falls among older adults in the South of Brazil: prevalence and determinants / Quedas em idosos no Sul do Brasil: prevalência e determinantes

ABSTRACT OBJECTIVE Evaluate the prevalence and the factors associated with the occurrence of falls among older adults. METHODS A cross-sectional study with a representative sample of 1,451 elderly residents in the urban area of Pelotas, RS, in 2014. A descriptive analysis of the data was performed and the prevalence of falls in the last year was presented. The analysis of demographic, socioeconomic, behavioral and health factors associated with the outcome was performed using Poisson regression with adjustment for robust variance according to the hierarchical model. The variables were adjusted to each other within each level and for the higher level. Those with p ≤ 0.20 were maintained in the model for confounding control and those with p < 0.05 were considered to be associated with the outcome. RESULTS The prevalence of falls among older adults in the last year was 28.1% (95%CI 25.9-30.5), and most occurred in the person's own residence. Among the older adults who fell, 51.5% (95%CI 46.6-56.4) had a single fall and 12.1% (95%CI 8.9-15.3) had a fracture as a consequence, usually in the lower limbs. The prevalence of falls was higher in women, adults of advanced age, with lower income and schooling level, with functional incapacity for instrumental activities, and patients with diseases such as diabetes, heart disease, and arthritis. CONCLUSIONS The occurrence of falls reached almost a third of the older adults, and the prevalence was higher in specific segments of the population in question. About 12% of the older adults who fell fractured some bone. The factors associated with the occurrence of falls identified in this study may guide measures aimed at prevention in the older adult population.

RESUMO OBJETIVO Avaliar a prevalência e os fatores associados à ocorrência de quedas em idosos. MÉTODOS Estudo transversal com amostra representativa de 1.451 idosos residentes na zona urbana de Pelotas, RS, em 2014. Foi realizada análise descritiva dos dados e apresentada a prevalência de quedas no último ano. A análise de fatores demográficos, socioeconômicos, comportamentais e de saúde associados ao desfecho foi realizada por meio de regressão de Poisson com ajuste para variância robusta conforme modelo hierárquico. As variáveis foram ajustadas entre si dentro de cada nível e para as de nível superior. Aquelas com p ≤ 0,20 foram mantidas no modelo para controle de confusão e aquelas com p < 0,05 foram consideradas associadas ao desfecho. RESULTADOS A prevalência de quedas em idosos no último ano foi de 28,1% (IC95% 25,9-30,5), e a maioria ocorreu na própria residência do idoso. Entre os idosos que sofreram queda, 51,5% (IC95% 46,6-56,4) tiveram uma única queda e 12,1% (IC95% 8,9-15,3) tiveram fratura como consequência, sendo a de membros inferiores a mais relatada. A prevalência de quedas foi maior em mulheres, idosos com idade avançada, de menor renda e escolaridade, com incapacidade funcional para atividades instrumentais e portadores de enfermidades como diabetes, doença cardíaca e artrite. CONCLUSÕES A ocorrência de quedas atingiu quase um terço dos idosos, e a prevalência foi mais elevada em segmentos específicos da população em questão. Cerca de 12% dos idosos que caíram, fraturaram algum osso. Os fatores associados à ocorrência de quedas identificados neste estudo poderão nortear medidas que visem sua prevenção na população de idosos.

Prevalence of sarcopenia among community-dwelling elderly of a medium-sized South American city: results of the COMO VAI? study.

BACKGROUND: There is insufficient data concerning sarcopenia prevalence in South America. The aim of this study was to estimate sarcopenia prevalence and its clinical subgroups in a Southern Brazilian city. METHODS: A cross-sectional population-based study was performed among community-dwelling elderly aged 60 years or over. Subjects were evaluated according to the European Working Group on Sarcopenia in Older People established criteria. Muscle mass was estimated by calf circumference (CC). Cut-off CC points were defined by a subsample's dual X-ray absorptiometry estimation of the appendicular skeletal muscle mass index (ASMI), which was subsequently compared with the values of a young adult population from the same city. Muscle strength was measured by manual dynamometry. Muscle performance was assessed through the 4 m gait speed test. RESULTS: The three diagnostic tests were performed in 1291 subjects. CC of ≤34 cm (males) and ≤33 cm (females) were defined as indicatives of low ASMI. The overall sarcopenia prevalence was 13.9% (CI95% 12.0; 15.8%). Its frequency was significantly higher among elderly with low schooling, without a partner, with low socioeconomic status, smokers, inactive, and with low body mass index. A higher prevalence of pre-sarcopenia was found in the youngest elderly; a higher prevalence of the clinical stages of the syndrome was found in older age groups. CONCLUSIONS: Approximately one in ten elderly aged 60-69 years was in the preclinical stage of the disease. This is the age group in which public policies should focus to establish early diagnosis and prevent clinical progression of the syndrome.

Phase angle and its determinants in healthy subjects: influence of body composition.

BACKGROUND: The phase angle (PA) has been used as a prognostic marker in several clinical situations. Nevertheless, its biological meaning is not completely understood. OBJECTIVE: We verified how body-composition components could explain the PA. DESIGN: The trial was a cross-sectional study involving 1442 participants (women: 58.5%; Caucasian: 40.2%) from body-composition studies. Labeled tritium dilution and total-body potassium were used to estimate total-body water (TBW) and intracellular water (ICW), respectively. Extracellular water (ECW) and the ECW:ICW ratio were estimated from the difference and the ratio of these values. Fat-free mass (FFM) and fat mass (FM) were estimated with the use of dual-energy X-ray absorptiometry, underwater weighing (UWW), and TBW. The PA was estimated with the use of a single-frequency bioelectrical impedance analysis system. Correlations between the PA and all body-composition variables were evaluated. A multivariate linear regression analysis was performed to adjust for the effects of body-composition variables on the PA variability. All analyses were performed separately by sex. RESULTS: Compared with men, women exhibited significantly larger ECW:ICW ratios and FM. The highest positive correlation was shown between the PA and FFM obtained with the use of UWW (both sexes). The highest negative correlation was shown between the PA and ECW:ICW ratios for both sexes. Age, race, height, ECW:ICW, and FFM from UWW were significant PA determinants in a multivariate linear regression model. Even after adjustment for all significant covariates, the explained PA variance was low (adjusted R(2) = 0.539 and 0.421 in men and women, respectively). The greatest impact on the total PA prediction in both men and women were age, FFM, and height. CONCLUSIONS: Age is the most significant PA predictor in men and women followed by FFM and height. The ECW:ICW contribution may explain the association of the PA observed in the clinical setting and in people who are obese.