Matheus Santos de Sousa Fernandes1, Gabriela Carvalho Jurema Santos2. 1. Programa de Pós-graduação em Neuropsiquiatria e Ciências do Comportamento, Centro de Ciências Médicas, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil. Electronic address: matheus.sfernandes@ufpe.br. 2. Departamento de Nutrição, Centro de Ciências da Saúde, Universidade Federal de Pernambuco - Recife, Pernambuco, Brazil.
Dear editorWe congratulate Bouziotis et al. [1] for the exceptional study, which evaluated the impact of body mass index (BMI) in hospital mortality in a large cohort of patients hospitalized for COVID-19, adjusting for demographic and health factors. First, our attention was directed to the use of available retrospective data for the elaboration of the present research. Due to the COVID-19 pandemic scenario, the execution of retrospective studies appears as a viable alternative for the publication of original data. However, due to this strategy, there may be a reduction in the reliability and reproducibility of the data, with the need for exclusion. Therefore, in the present study, the authors had to exclude data considered incorrect for BMI (under 10 kg/m2 and above 100 kg/m2). We suggest in future studies the inclusion of analyzes that attest to the reproducibility and quality of the included data that can be applied among the evaluators [2,3].Second, we highlight the heterogeneity of the sample. The interference of different sex hormones (estrogen, progesterone, and testosterone) on anthropometric variables including BMI is widely known, which can lead to different health and disease outcomes. The performance of retrospective studies in cohorts with assessment of the sexes separately and of sex hormone levels, can help in the broad understanding of the possible association with BMI and mortality from COVID-19 in these subjects [4,5].Third, as this is a population-relevant study in 48 countries around the world, we believe that the inclusion of a justification through the execution of the sample calculation would be essential to justify the number of participants included in the study. In addition, with a view to preparing future studies, the explanation on the percentage of patients by continent or nationality should be included, as we know that different socioeconomic and cultural situations can impact the heterogeneity of responses in the BMI and the prognosis and mortality of patients by COVID -19. Finally, we once again highlight the relevant contribution of the study by Bouziotis et al. to the scientific community. And we ratify our suggestions for conducting future studies, with the aim of contributing with analyzes that help explain the different effects caused by COVID-19 around the world.
Author contributions
MSSF and GCJS: concept, interpretation, writing of the manuscript.All authors critically reviewed the manuscript for important intellectual content and approved the final version of the manuscript.