Heart failure (HF) is a clinical syndrome characterized by the heart’s inability to supply the body’s metabolic demands or to do so at the expense of high filling pressures as a result of structural or functional abnormalities of the heart.1 It is the common final pathway of a number of cardiac diseases that determine activation of the neurohormonal and inflammatory axis and energetic metabolism, resulting in cardiac cachexia, worsening the prognosis and greater morbidity and mortality of individuals with HF.2 On the other hand, overweight protects individuals with HF, which is called the “obesity paradox”.3

In this context, methods of anthropometric assessment and body composition are proposed, but without consensus.4 Although the body mass index (BMI) does not clearly reflect body composition, low values for this index have been associated with worse prognosis in individuals with HF, whereas increased values act as a protective factor.5^,6 The evaluation of triceps skinfold thickness (TST) is a way of identifying adiposity in these individuals and is related to the prognosis of the disease.7 Other parameters of indirect musculature assessment, such as the arm muscle circumference (AMC) and corrected arm muscle area (cAMA) are widely accepted, but there are few studies that consolidate its use in HF.8 Another parameter used as an indicator of musculature reserve is the adductor pollicis muscle thickness (APMT).9

More accurate methods for assessing body composition, such as computed tomography and magnetic resonance imaging, are costly and difficult to perform.10 As an alternative, electrical bioimpedance (EBI) has been suggested and can be used to evaluate the prognosis and follow-up of individuals with HF.11 However, the higher cost of acquiring the equipment makes anthropometry the most feasible method for outpatient evaluation and follow-up, despite its still questionable sensitivity and accuracy.12

Given the controversies between the methods of anthropometric evaluation and body composition in individuals with HF, and the scarcity of specific indicators in the literature, the objective of this study was to evaluate the accuracy and concordance of the diagnosis of protein malnutrition and excess fat among anthropometric and body composition methods.

The mean age of the individuals was 55.3 (13) years, predominantly males (70%), and diagnosis of HF with non-ischemic etiology (55%). Significant percentages of individuals with hypertension (70%) were found. Most individuals were in functional class I (76.7%), despite the diagnosis of 60% of the individuals with reduced ejection fraction heart failure (HFrEF). The BMI revealed that the study population presented average values ​​indicative of overweight and total body water (TBW) percentage within normality (Table 1).

It was found that protein malnutrition, when evaluated by cAMA (43.9%) and AMC (40%), was more frequent when compared to FFMI (13.2%), BMI (11.7%) and APMT (5.1). There was similarity in the diagnoses of excess fat indicators, where BF was the one that identified a higher frequency of excess fat (63.5) (Table 2).

Analyzing the indicators of accuracy of anthropometric measures related to protein malnutrition, it was found that BMI presented low sensitivity (43%) and accuracy (38.5%), but moderate concordance (0.50). On the other hand, AMC presented greater sensitivity (86%) and accuracy (66.4%) with acceptable concordance (0.36) compared to FFMI, being considered acceptable for the diagnosis of protein malnutrition. It was not possible to calculate the accuracy and concordance for the cAMA and APMT indicators because one of the categories presented a null value (Table 3).

Regarding overweight, the anthropometric measures related to BF% revealed similarity between the percentage of sensitivity of the TST (60%) and BMI (67%) indicators, as well as low accuracy (20.3% and 22.2%, respectively). Considerable concordance values ​​were found for both indicators, compared to BF% (Table 4).

This pioneering study certifies the complexity of anthropometric assessment and body composition in individuals with HF. The results showed that there was a higher frequency of excess fat/weight than of protein malnutrition in our population diagnosed with HF. Among the methods of anthropometric evaluation reviewed, AMC was considered more sensitive for the diagnosis of protein malnutrition, despite the lower concordance with EBI. Indicators of excess fat/adiposity presented similar results and low sensitivity.

Comorbidities diagnosed in individuals with HF may coexist or even be the cause of the disease, having a negative impact on the quality of life, increasing the frequency of hospitalization and mortality.22 In this study, a higher frequency of arterial hypertension was observed, as found in other studies that also identified higher frequencies of this comorbidity, in addition to diabetes mellitus.23

One fact that caught our attention was that more than half of the participants had reduced ventricular ejection fraction (HFrEF), but from a clinical point of view, they were classified as functional class I. This is opposed to the findings reported by Garlet. et al.,24 whose data revealed that individuals with HF evaluated in functional class I presented higher LVEF than those in functional class II, III or IV. At this point, it can be said that the inconsistent data can be due to the fact that the individuals with HF in our study are followed up, in an outpatient setting, by a well-structured interprofessional and multidisciplinary team, reinforcing that high-quality multidisciplinary care can benefit individuals with HF in the prevention or early detection of acute decompensation.25^,26

It is important to know the state of clinical compensation of individuals with HF upon anthropometric and body composition evaluation, as it may have repercussions on inaccuracies due to the inability to follow the evaluation protocols in the presence of symptoms. In our study, it was found that the participants had body water volume within the acceptable ranges. It has been found that the total body water volume of individuals with compensated HF is reported to be equal to that of normal individuals.23 Studies evaluating total, intercellular and extracellular body water volumes in individuals with HF, either followed up in an outpatient setting or not, but who were compensated at the time of the evaluation, found results similar to those of this study.27^-29

Analyzing the diagnosis of indicators of protein malnutrition/muscle depletion, we found discrepancies between anthropometric and body composition methods. Although reduced sensitivity presents moderate concordance, it suggests that BMI assessment compared to other methods is not a good predictor of protein malnutrition. Authors reaffirm this finding, pointing out that BMI may not provide a good overview of the nutritional status of patients with HF, especially when used for the diagnosis of malnutrition, as this index does not distinguish between fat and lean body mass.30

However, the literature is controversial when it recommends the use of BMI as a marker of prognosis in individuals with HF. A retrospective study comparing the levels of N-terminal pro-brain natriuretic peptide (NT-proBNP), which is a strong risk factor for mortality, for the increase in the BMI of individuals with decompensated HF, suggests that overweight is not associated with mortality in this population, reporting that BMI is inversely proportional to the increase of NT-proBNP.31 However, Cescau et al.,32 found that although BMI is not an independent predictor of mortality, it is significantly related to greater reverse myocardial remodeling, promoting a protective effect of overweight in the course of HF. In a meta-analysis that assessed the association between BMI and all causes of death in individuals with HF, it was found that both BMI corresponding to malnutrition and morbid obesity are associated with higher mortality in this population.33

On the other hand, for the evaluation of muscle depletion, AMC and cAMA identified higher percentages of individuals with muscle depletion, with AMC being the most sensitive one, with acceptable concordance with the FFMI parameter. In view of these findings, it is assumed that the AMC and cAMA anthropometric indicators may overestimate the cases of muscle depletion, which may be associated to the evaluation method, which presupposes equations that require the value of two anthropometric measures, as well as classification in tables of percentiles.

However, considering the importance of monitoring the skeletal muscles of individuals with HF, since cachexia and sarcopenia are associated with worse prognosis and higher mortality,34 it is preferable to use the AMC values even in a potential overestimation of malnutrition due to the impossibility of acquiring and maintaining more sensitive equipment such as EBI.

For the APMT, a lower frequency of muscle depletion was found, compared to FFMI, suggesting that this measure has a reduced diagnostic capacity to evaluate compensated individuals followed up in an outpatient setting as in this study. However, its use in an intensive care unit has proven to be a good method of assessing nutritional risk.35

One of the most striking aspects of our study was the high percentage of individuals who had excessive adiposity/fat. This fact may have a positive impact on the course of the disease, since there is an inverse association between overweight or obesity and mortality in individuals with HFrEF, as found in our population.36 In our study, there was a uniformity of diagnoses considering the indicators used for this purpose. However, both BMI and TST showed low sensitivity, accuracy and concordance with the percentage of fat evaluated by EBI.

Caution is needed in this interpretation, especially when BMI is used for assessing body fat. A prospective study with patients with HF found results similar to ours for the diagnosis of BMI. The authors raise questions that individuals with protein malnutrition may possibly be classified as overweight by BMI, underestimating cases of malnutrition and increasing the risk of mortality.37

According to a study that investigated the association between body composition assessed by dual energy x-ray absorptiometry (DEXA), an imaging test that promotes the identification of body extracts (gold standard) and mortality of patients with HF, it was observed that the BMI misclassified 41% of patients for body fat,5 similarly to the one found in our study, where we identified 50% of negative predictive value for BMI.

Although our results did not confirm good indicators of accuracy and concordance of TST in the evaluation of excess adiposity, other authors point out the use of TST as a predictor of mortality, further reinforcing the obesity paradox, since excess TST presented an inverse relation with mortality.7 It is suggested to evaluate subcutaneous fat from the association between multiple skinfolds, used in formulas to evaluate adiposity, as well as was evaluated by Gastelurrutia et al.,37 associated with other methods to identify the nutritional status of individuals with HF, aiming to identify adipose reserve more accurately when there is no evaluation of fat percentage by EBI.

Our study is not free of limitations: (1) the low frequency of anthropometric disorders may be biased in the statistical analysis; (2) a small number of participants may have caused lower values ​​of sensitivity and concordance, but the results found were relevant to signal the need to consider several methods of assessing body composition in this population.

The results reveal important information about the use of anthropometric indicators in the evaluation of individuals with HF, reinforcing that, for a more accurate evaluation, EBI assessment may be better indicated. EBI measurements should be standardized to obtain reproducible results and the use of body composition prediction equations must meet the specifications of each population studied. It should be noted that when it is not feasible to use equations already defined in specific studies, it is possible to use data from the EBI provided by the equipment at the time of measurement, such as resistance (R) and reactance (Xc) data, resulting in the formation of data such as phase angle, which is used in the diagnosis of malnutrition and clinical prognosis. Additionally, another potential data for the diagnosis and prognosis of body mass reserves is the analysis of bioelectrical impedance vectors.38^,39

In conclusion, it is suggested that although AMC overestimates muscle depletion, it can be used as an indicator of protein malnutrition. In addition, BMI was not sensitive in the evaluation of muscle and body fat components, therefore caution is recommended in the use of this indicator in patients with compensated HF followed up in an outpatient setting. TST did not present good sensitivity for the evaluation of adiposity and body fat, reinforcing the importance of the evaluation considering multiple folds. The anthropometric parameters should be incorporated into the clinical practice for their low cost and practicality, but for greater accuracy in the evaluation of body composition, more accurate methods, such as EBI, should be considered.