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This research is the first to evaluate in great detail the utility of the Mini Nutritional Assessment (MNA) in both its short version (MNA-SF) and its long version (MNA-LF) in detecting sarcopenia in institutionalized older people (Residential Place of the Elderly), based on the definition of the European Working Group on Sarcopenia in Older People 2 (EWGSOP2), in which sarcopenia is classified as probable sarcopenia by the presence of low muscle strength, confirmed sarcopenia by the presence of low muscle strength and low muscle quantity or quality, and severe. This is very important, since this definition of this disease has been changing over time, subject to different criteria, as well as the ways of diagnosing it, however, access to these objective and expensive diagnostic studies is not entirely equitable, especially in developing countries such as Mexico and Latin America where there is not wide availability, especially in institutional places where care is provided to older people, so studying a screening tool that allows nutritional or other interventions in institutionalized patients acquires great clinical relevance, since firstly it is something practical to implement that does not require much training by staff and less sophisticated equipment, so established and severe sarcopenia can be prevented in the future, thus preventing greater future complications derived from it such as fractures and recurrent falls that decrease the quality of life of older adult patients as well as increase depression, which some patients already present, as well as the pharmacological burden and poor nutritional status, directly impacting the quality of life of these patients and on the other hand what this represents for the health system of each country. This study found that subjects with MNA-SF <13 were 2 times more likely to have sarcopenia (OR=2.36; 95% CI: 1.02-5.45; p=0.04) after adjustment for sex and age, while MNA-LF cut-off scores were not associated with sarcopenia. Concluding that According to the AUC, MNA-SF may be useful for detecting sarcopenia in institutionalized older people, while MNA-LF may have reduced utility in clinical practice, however the authors clarify that the results obtained from the long-form comprehensive assessment (MNA-LF) may be due to a lack of statistical power or a type 2 error, since a larger sample of this population was not available, which should be explored in other types of studies with larger population samples. This study may lay the groundwork for evaluating this new hypothesis in this subgroup of patients. This should be explored in larger studies that allow for inferring causality, with a larger sample and representativeness in order to validate or refute this hypothesis. If the results are positive, this would have a high impact on the way these patients are evaluated, not only in hospitals, but also in institutional centers where there may be a higher prevalence of sarcopenia due to all the factors involved in the environment of retirement homes for the elderly. In a few years, the number of elderly subjects, or those suffering from pathologies such as cancer, as well as disabling diseases, would be much higher than at present, where these centers will have a greater demand. This makes early detection of sarcopenia a main objective for the future, since this disease could generate a global public health problem with major impacts in all areas of health, social and economic. However, with more far-reaching and easier tools, public health strategies can be created to prevent it.

• List significant concerns about the research, if there are any.

  There is none

Minor issues

• List concerns that would improve the overall flow or clarity but are not critical to the understanding and conclusions of the research.

Everything is explained very clearly, as is the research question, objectives, and hypothesis being posed.

Something I would like to add is that the literature details the MNA scale, which is the full version, and the validated short version, which is the MNA-SF, as you described in this paragraph of the methods section, in the abstract “Cross-sectional study in adults aged 55 years and older from the city of Puebla. The MNA in its short form (SF) and full form (LF) were administered. The diagnosis of sarcopenia was made according to EWGSOP2. Points obtained from MNA-SF and MNA were plotted on a ROC curve. The odds ratio (OR) for presenting sarcopenia was evaluated according to recommended cutoff points with logistic regression models, adjusted for age and sex.” It is described in two ways, as MNA-LF the long version and as MNA-SF however I consider that the long version should be written as MNA, since in the literature consulted by you, I see that the articles refer to it only as MNA referring to the long version and not as MNA-LF, when I searched to know about this scale when I wrote MNA-LF I did not find any reference to it, only as MNA and MNA-SF so I think that the reader will find it easier to find it as MNA, so that he can take it into account, and thus his article will be mostly seen and found in the databases during the searches.

Other minor issues

In the results section

“162 participants were included, 64.1% were women, the mean age was 69.8 years (SD:5). The mean scores of MNA-SF and MNA-LF were 12.17 (SD:1.78), and 25.1 (SD:2.83), respectively. The prevalence of sarcopenia was 20.4%. The AUC of MNA-SF was 0.68 (95%CI:0.58-0.78) and for MNA-LF, 0.60 (95%CI:0.49-0.71). The OR for presenting sarcopenia with MNA-SF<12 was OR=2.87 (95%CI:1.31-6.29) and, after adjustment for age and sex, OR=2.47 (95%CI:1.10-5.54).” The described percentage of 64.1% of participating women, as well as it is mentioned in the article on two occasions, is not in table 1 of the results of the study sample and the characteristics, I think it should be, especially since adjustments were made for age and sex, due to the characteristics related to the musculature that differ by sex and age. On the other hand, in the results section you describe this “the prevalence of sarcopenia was 20.4%. The AUC of MNA-SF was 0.68 (95%CI:0.58-0.78) and for MNA-LF, 0.60 (95%CI:0.49-0.71). The OR for presenting sarcopenia with MNA-SF<12 was OR=2.87 (95%CI:1.31-6.29) and, after adjustment for age and sex, OR=2.47 (95%CI:1.10-5.54).” However, the value of 2.87 only appears again in table number 5, however in the full article it is not mentioned on page 10 when describing the main results it is only described when it is less than 13 “Table 5 shows the results of logistic regression models to determine the odds of detecting sarcopenia and each component by the cutoff points of MNA-SF and MNA-LF. Subjects with MNA-SF <13 had 2 times higher odds of presenting sarcopenia (OR=2.36, 95% CI: 1.02- 5.45, p=0.04) after adjustment for sex and age, while MNA-LF cutoff points were not associated with sarcopenia” Therefore I think that in this section the value less than 12 should also be described since it is the most important and it is mentioned in the abstract.

I think it is also important to define the type of sampling used, which from what I could read implicitly, is a convenience sampling, however I think it is good to describe it in the corresponding section, especially in this type of cross-sectional studies, and what strategies were taken to limit the biases derived from it, I consider that the sample is representative of the population, since they take into account a very wide age range, which increases variability and representativeness, as well as the adjustment they made for sex and age, which is a good strategy since they are the main confounders of it, as well as the sample calculation that is not reflected, as the strobe guides refer to, however I know that it is not a requirement to put it in some journals, since it is assumed that this same calculation was made by the authors.

I also think that the limitations of your study should describe a little more about the biases that are subject to when filling out the evaluation, as well as the biases of the design to which it is subject, also describe a little, if possible, the role of the interviewer, in filling out the evaluations, since there are many, and especially those of the long format include many more items, and are subject to observation, memory, and interviewer bias, as well as the measures taken to reduce these biases, I think that would give more strength to your study, as well as when you described in the variables section, that each measure taken was very well described.

Finally, I only have one doubt regarding the sensitivity values ​​described here for the short and long evaluations.

“Table 4 shows the sensitivity and specificity values ​​for the suggested cutoff points for both MNAs and for the cutoff points recommended to define an alteration in nutritional status, for sarcopenia detection, and for each diagnostic criterion. It was observed that the cutoff points MNA-SF <12 and MNA-LF <24 showed higher sensitivity for sarcopenia, low strength, and low muscle mass detection.”

It is mentioned in the table that the highest sensitivity values ​​were obtained for those values, but as far as I can see in table 4 the highest sensitivity values ​​for sarcopenia, low strength and low muscle mass detection, were for values lower than MNA-SF <13 and MNA-LF <25.5, except low muscle performance in which the values ​​MNA-SF <12 and MNA-LF <24 were the highest for sensitivity in this section, so I don't know if it is an error in the table, or it is poorly described in the table 4 section previously described in the results section.

Conclusions

I would like to congratulate you for this great work, novel, relevant, well designed and with a great clinical significance to explore, since you raise a very interesting hypothesis, which should be replicated in other larger studies and where they allow long-term studies and a longer follow-up, to determine if elderly patients at risk of malnutrition can later present sarcopenia. And that this is a new screening tool that is easier to use and with good sensitivity.

Competing interests

I know two of the authors, as well as their careers, however we have not collaborated on any research project until the time of this review that I am carrying out.