Visceral fat is associated to the severity of COVID-19

Abstract

Background: Excess visceral fat (VF) or high body mass index (BMI) is risk factors for severe COVID-19. The receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is expressed at higher levels in the VF than in the subcutaneous fat (SCF) of obese patients.

Aim: To show that visceral fat accumulation better predicts severity of COVID-19 outcome compared to either SCF amounts or BMI.

Methods: We selected patients with symptomatic COVID-19 and a computed tomography (CT) scan. Severe COVID-19 was defined as requirement for mechanical ventilation or death. Fat depots were quantified on abdominal CT scan slices and the measurements were correlated with the clinical outcomes. ACE 2 mRNA levels were quantified in fat depots of a separate group of non-COVID-19 subjects using RT-qPCR.

Results: Among 165 patients with a mean BMI of 26.1 ± 5.4 kg/m², VF was associated with severe COVID-19 (p = 0.022) and SCF was not (p = 0.640). Subcutaneous fat was not different in patients with mild or severe COVID-19 and the SCF/VF ratio was lower in patients with severe COVID-19 (p = 0.010). The best predictive value for severe COVID-19 was found for a VF area ≥128.5 cm² (ROC curve), which was independently associated with COVID-19 severity (p < 0.001). In an exploratory analysis, ACE 2 mRNA positively correlated with BMI in VF but not in SCF of non-COVID-19 patients (r² = 0.27 vs 0.0008).

Conclusion: Severe forms of COVID-19 are associated with high visceral adiposity in European adults. On the basis of an exploratory analysis ACE 2 in the visceral fat may be a trigger for the cytokine storm, and this needs to be clarified by future studies.

Keywords: Angiotensin-converting enzyme; Coronavirus disease 19; Obesity; Severe acute respiratory syndrome coronavirus 2; Subcutaneous fat; Visceral fat.