To the Editor,
We would like to congratulate Bonilla et al.1 on their study on malnutrition and mortality in hospitalized patients, which was recently published in Revista Española de Cardiología. We would also like to make some practical observations.
From a methodological point of view, we would like to point out that there may have been a sample selection bias. The study selection criteria excluded patients who were not able to stand up to be weighed or measured or who were not able to undergo the Mini Nutritional Assessment® (MNA®) due to functional deterioration prior to admission or which developed during the hospital stay. The exclusion of patients with worse function probably resulted in a prevalence of malnutrition that was lower than the actual situation. Given that the demographic and comorbidity characteristics were not compared between the excluded and included patients, we cannot discount the possibility that there were differences, which constitutes a study limitation. We also think that it would be appropriate to clarify whether skinfold and circumference measurements were taken by one or several observers, as this could affect reproducibility and consistency.
The authors assessed the impact on survival of several isolated comorbidities. However, they did not measure the impact on survival of the comorbidities as a whole (Charlson index) or of the patients’ functional situation, which have been reported in other studies.2, 3 There is a well-known relationship between nutritional state, functional deterioration, and comorbidity, and so we cannot discount the possibilty that these factors acted as confounding variables that went unanalyzed.
Furthermore, the studies used to validate the nutritional screening tool (MNA®) were performed on patients over 65 years old. Although there are some studies in other age groups, this method is recommended and validated only for this one, as its creators have acknowledged4, 5 and the European Society for Clinical Nutrition and Metabolism guidelines indicate.6 In this study, more than 16% of the patients were younger than 65 years. The MNA® consists of 18 items and can be completed in less than 15min. To simplify and improve its use, the MNA® screening has been revalidated (Short Form MNA®), using data from 28 previously published studies.7 The new Short Form MNA® incorporates 3 nutritional situation cut-off points, which allows patients to be classified with only 6 questions. Furthermore, calf circumference can be used when the body mass index is not available.7 As such, the complete MNA® no longer needs to be used, and the new Short Form MNA® reduces the nutritional screening time to less than 5min and is currently recommended for clinical use.7
As the authors note, it is important to detect malnutrition or risk of malnutrition early, because mortality quadruples.1 The MNA® (and the new Short Form MNA®) is a simple, reproducible tool, validated for people over 65. It identifies risk of malnutrition before significant changes in weight or albumin levels occur, which allows direct nutritional intervention, monitoring of compliance, and assessment of the effectiveness of the nutritional intervention.5, 6, 7 We agree with the authors that nutritional support and/or monitoring can improve prognosis for these patients. There is evidence that the administration of nutritional supplements reduces mortality in older malnourished patients,8 meaning that it is important to detect malnutrition in these patients.
Corresponding author: lsanchezmunoz@gmail.com