Reply to: 'Younger patients with MAFLD are at increased risk of severe COVID-19 illness: A multicenter preliminary analysis'.

To the Editor:

We read with interest the letter by YJ Zhou et al. stressing the finding that, in their own series, metabolic-associated fatty liver disease (MAFLD, also termed non-alcoholic fatty liver disease [NAFLD]) is associated with an increased risk of severe COVID-19 illness in younger but not older patients. As pointed out by the authors, a notable limitation of the study was the smaller sample size of the cohort of older patients, which might influence the validity of the results. Actually, if both age groups were combined together and analyzed as a whole, patients with MAFLD had a high likelihood of severe disease compared to those without MAFLD (26.9% vs. 14.5% p = 0.004). If multivariate analysis had been performed with the whole cohort, there was a high likelihood that MAFLD would be an independent risk factor for severe COVID-19, as we observed.

That said, in our previous study, which included 520 Chinese patients with biopsy-proven MAFLD, statistically significant negative correlations between age and liver inflammation or fibrosis were found. This observation suggested that younger NAFLD/MAFLD patients might have more inflammation, resulting in an increased risk of severe COVID-19 as shown in Zhou's study.

Therefore, in our opinion, both studies suggest that fatty liver disease is an independent risk factor for severe COVID-19 across all age groups. Further studies are warranted to understand the role of NAFLD/MAFLD in the immunopathogenesis of COVID-19.

Financial support

This work is funded by the Capital Characteristic Clinic Project of (Z181100001718034).

Authors' contributions

DJ and EQ wrote the manuscript; GL provided guidance and proof-read the manuscript; all authors revised and approved the final version.

Conflict of interest

We declare no competing interests.

Please refer to the accompanying ICMJE disclosure forms for further details.