Letter to the Editor: Obesity as a risk factor for greater severity of COVID-19 in patients with metabolic associated fatty liver disease
Authors: Abdulzahra Hussain, Peter Vasas, Shamsi EL-Hasani
Journal: Metabolism (2020)

Dear Sir, We read with interest the article by K·I Zheng et al. [[1]Zheng K.I. Gao F. Wang X.-B. et al.Obesity as a risk factor for greater severity of COVID-19 in patients with metabolic associated fatty liver disease.Metabolism. 2020; https://doi.org/10.1016/j.metabol.2020.154244Abstract Full Text Full Text PDF Scopus (232) Google Scholar], we congratulate the authors for their work and conclusions. Although the definition of obesity in this article is slightly different from the internationally accepted criteria, however, the authors had successfully used the data to answer the research question. Many studies had reported non-alcoholic fatty liver disease [NAFLD] and non-alcoholic steatohepatitis [NASH] in association with obesity [2Sheka A.C. Adeyi O. Thompson J. Hameed B. Crawford P.A. Ikramuddin S. Nonalcoholic steatohepatitis: a review.JAMA. 2020 Mar 24; 323 ([Review]): 1175-1183https://doi.org/10.1001/jama.2020.2298Crossref PubMed Scopus (715) Google Scholar, 3Ooi G.J. Burton P.R. Bayliss J. Raajendiran A. Earnest A. Laurie C. et al.Effect of body mass index, metabolic health and adipose tissue inflammation on the severity of non-alcoholic fatty liver disease in bariatric surgical patients: a prospective study.Obes Surg. 2019 Jan; 29: 99-108https://doi.org/10.1007/s11695-018-3479-2Crossref PubMed Scopus (27) Google Scholar, 4Albhaisi S. Sanyal A.J. Applying non-invasive fibrosis measurements in NAFLD/NASH: progress to date.Pharmaceut Med. 2019 Dec; 33: 451-463https://doi.org/10.1007/s40290-019-00305-zCrossref PubMed Scopus (19) Google Scholar, 5Nikai H. Ishida K. Umemura A. Baba S. Nitta H. Sugai T. et al.Effects of laparoscopic sleeve Gastrectomy on non-alcoholic steatohepatitis and liver fibrosis in Japanese patients with severe obesity.Obes Surg. 2020 Mar 2; ([Epub ahead of print])https://doi.org/10.1007/s11695-020-04515-2Crossref PubMed Scopus (17) Google Scholar]. These two conditions are not specific to the obese or overweight patients but also affecting non-obese population with risk of progression to cirrhosis, fibrosis and hepatocellular cancer [[6]Kumar R. Priyadarshi R.N. Anand U. Non-alcoholic fatty liver disease: growing burden, adverse outcomes and associations.J Clin Transl Hepatol. 2020 Mar 28; 8 ([Epub 2019 Dec 28]): 76-86https://doi.org/10.14218/JCTH.2019.00051Crossref PubMed Scopus (121) Google Scholar]. The NAFLD and NASH have been diagnosed frequently with liver biopsies, but also liver imaging cross sectional studies which were provided the diagnosis and the assessment of the disease progression. Not only, NASH and NAFLD are important predictive factors for the outcomes in acute and chronic disease processes but also the obesity surgery and its complications [[7]Goossens N. Hoshida Y. Song W.M. Jung M. Morel P. Nakagawa S. et al.Nonalcoholic steatohepatitis is associated with increased mortality in obese patients undergoing bariatric surgery.Clin Gastroenterol Hepatol. 2016 Nov; 14 ([Epub 2015 Oct 20]): 1619-1628https://doi.org/10.1016/j.cgh.2015.10.010Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar]. We think that the authors had reached the correct conclusion indirectly, as obesity is the primary aetiology for the liver disease [NASH, NAFLED] and rarely considered as independent conditions. When they coexist, they do so because of obesity. Several other studies have reported obesity as a significant factor for mortality in Covid-19 patients [8Caussy C. Wallet F. Laville M. Disse E. Obesity is associated with severe forms of COVID-19.Obesity (Silver Spring). 2020 Apr 21; ([Epub ahead of print])https://doi.org/10.1002/oby.22842Crossref PubMed Scopus (127) Google Scholar, 9Kassir R. Risk of COVID-19 for patients with obesity.Obes Rev. 2020 Apr 13; https://doi.org/10.1111/obr.13034Crossref PubMed Scopus (281) Google Scholar, 10Simonnet A. Chetboun M. Poissy J. Raverdy V. Roulette J. Duhamel A. et al.Lille Intensive Care COVID-19 and Obesity study group. High prevalence of obesity in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) requiring invasive mechanical ventilation.Obesity (Silver Spring). 2020 Apr 9; ([Epub ahead of print])https://doi.org/10.1002/oby.22831Crossref PubMed Scopus (1375) Google Scholar].This subject is more important in the current Covid-19 crisis knowing the pandemic of obesity. In addition to the known defective immune system in the obesity, the virulence of Covid-19 and the differences in the incidence of obesity across the world, it is not clear what is the magnitude /severity of liver disease could add to production of critical illness like severe pneumonia. We believe more powerful studies are needed to confirm why obesity is a risk factor for critical illness and or mortality in Covid-19. This will help to reduce mortality in this vulnerable group of patients. Authors confirm no conflict of interest and no funding for this paper.