key: cord-0771643-uwywpv5d
authors: Chen, Liping; Fan, Zhenyu; Cheng, Jilin
title: Reply to COVID-19 morbidity and severity in patients with non-alcoholic fatty liver disease in South Korea: a nationwide cohort study
date: 2021-10-09
journal: Clin Gastroenterol Hepatol
DOI: 10.1016/j.cgh.2021.10.009
sha: dc1788e9ab8a7560d733b1ca7bd4a263a221b5b7
doc_id: 771643
cord_uid: uwywpv5d

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The pandemic and inextricable relationship of COVID-19 and NAFLD have raised worldwide concerns. Although there was no population-based cohort study, some studies indicated NAFLD play a role in the outcome of COVID-19 and is an independent predictor of severe COVID-19. [1] [2] [3] So we read with great interest the cohort study conducted by Hae et al 4 regarding the effect of NAFLD on the COVID-19 related outcomes. However, we have some concerns. As shown in the study, the proportions of NAFLD was high (up to 73.2%) and individuals might have been misclassified as NAFLD in this study. More importantly, liver enzymes are important component of criteria used to define NAFLD; patients with SARS-CoV-2 infection are prone to elevated liver enzymes. It is likely that subjects classified as NAFLD based on claims-based definition were more likely to have NAFLD than those classified based on other criteria. Since patients with claim-based NAFLD had higher infection risk and severe progression for COVID-19 than subjects without claim-based NAFLD, then why was there no higher mortality in patients with claim-based NAFLD. Moreover, it is unclear if patients with HBV, HCV and HIV were excluded from the analysis. We also have doubts about a few values. For example, there were 2,251 cases who tested positive for SARS-CoV-2 (beginning of results section). However, there were 561/629 COVID-19 cases reported in subjects without/with FLI-NAFLD; these were 1925/323 COVID-19 cases reported in subjects without/with claim-based NAFLD, respectively. Besides, neither the number of COVID-19 nor the number of NAFLD was consistent within the groups classified by FLI and claims based NAFLD.

In addition, a preliminary analysis was conducted in all the NAFLD population, but not among subgroups. Previous research reported the liver fibrosis in NAFLD might represent an additional and independent risk factor for severe COVID-19 illness. 1 It would be interesting to analyze the relationship between different degrees of fatty liver and SARS-CoV-2's infectivity by longitudinal observation.

COVID-19 and nonalcoholic fatty liver disease: Two intersecting pandemics

NAFLD and COVID-19: a Pooled Analysis

Nonalcoholic fatty liver disease is associated with COVID-19 severity independently of metabolic syndrome: a retrospective case-control study

COVID-19 morbidity and severity in patients with non-alcoholic fatty liver disease in South Korea: a nationwide cohort study