Isabel Correia, Professor of Surgery, Universidade Federal de Minas Gerais, Brazil

Universidade Federal de Minas Gerais

Professor of Surgery at Universidade Federal de Minas Gerais, Belo Horizonte, Brazil

Co-editor in chief of the Nutrition the Journal of Basic and Applied Sciences.

Diagnosing malnutrition

Remote speaker / Presenting virtually

Diagnosing malnutrition has been a quest over decades, although there have been different tools to carry out the assessment. However, there is still confusion in the current literature and clinical practice regarding the differences between screening for malnutrition and assessing it. The former identifies risk factors while the latter provides the diagnosis per se. However, it is even more challenging to acknowledge that the definition of the syndrome seems to be a matter of discussion, although it has been well shown that individuals (from children to the elderly) who for different reasons fail to reach their nutrient requirements, due to any specific reason, and lose weight, suffer deleterious consequences throughout their life journey, in particular, when sick.

From a simple and direct perspective, the decrease in food intake of any cause affects body composition, both muscle, and adipose compartments, but it also negatively impacts immunologic defenses and metabolic pathways. If the reason for diminished nutrient intake is a disease state, then it may coexist malabsorption or nutrient losses, as well as altered metabolism and inflammation, leading to worsening of the nutrition balance. Therefore, malnutrition encompasses decreased nutrient intake, altered body composition as well as metabolic, immunologic, and inflammatory derangements. It would thus seem easy to diagnose this syndrome as long as an adequate clinical history of the patient with a physical body assessment was carried out. Nonetheless, as mentioned, it has been a matter of discussion, with some defining it based on objective measurements alone such as decreased food intake, body weight, height, body mass index, circumferences, skinfolds, or body composition methods either simple as bioimpedance or more sophisticated as tomography, while others rely on muscle functionality tests like the six-minute walk, handgrip strength or sit and stand technique. Furthermore, for each of these mentioned instruments, there are also various cutoffs according to the studied populations which make it hard to reach a consensus, in particular when there is an obesity pandemic worldwide which per se impacts body composition. On the other hand, a subjective evaluation, as the subjective global assessment tool, is based on clinical reasoning that has been well shown to be reliable and valid in providing the diagnosis of malnutrition, and it predicts outcomes with good sensibility and specificity, is not well known among non-clinician or non-nutrition experts. It also has a downside which requires well-trained professionals to perform it. Considering all the challenges and the wide variations of the used instruments, which affect prevalences and coding, the Global Leadership Initiative on Malnutrition proposed a framework of three phenotypic and two etiologic variables to classify the nutritional status. However, its various combinations need to be validated to avoid inadequate sensitivity and specificity of the many combinations which may jeopardize the adequate diagnosis of malnutrition.

Identifying the syndrome malnutrition is paramount to early treating it and improving morbidity, length of stay, mortality, and costs. The problem is that in sick individuals there are many more variables influencing not only the nutritional status but also the overall outcomes, making it hard to solely relate the nutrition status with better results, in particular when many of the objective nutrition measurements are also impacted by other variables such as hydration, bed rest and medications, while the subjective assessment poses an even more difficult follow-up instrument. On the other hand, it is undoubtedly, that without food life is not sustained for more than about six weeks based on data from hunger strikers. Thus it seems absolutely convincing that nutrition therapy plays a major role in the overall holistic approach of the sick individual who is not eating for any reason or has lost body compartments and functionality while presenting with inflammation or altered metabolic status. In conclusion, any tool alone or in conjunction that assesses these derangements will provide the diagnosis of malnutrition.