Erector Spinae Muscle to Epicardial Visceral Fat Ratio on Chest CT Predicts the Severity of Coronavirus Disease 2019

BACKGROUND: Chest computed tomography (CT) is a valuable tool for diagnosing and predicting the severity of coronavirus disease 2019 (COVID-19) and assessing extrapulmonary organs. Reduced muscle mass and visceral fat accumulation are important features of a body composition phenotype in which obesity and muscle loss coexist, but their relationship with COVID-19 outcomes remains unclear. In this study, we aimed to investigate the association between the erector spinae muscle (ESM) to epicardial adipose tissue (EAT) ratio (ESM/EAT) on chest CT and disease severity in patients with COVID-19. METHODS: We analysed data from 1074 COVID-19 patients enrolled in the Japan COVID-19 Task Force database. The primary outcome was the rate of critical outcomes (requiring high-flow oxygen therapy, invasive ventilator support or death). The incidence of critical outcomes was compared between patients with high and low ESM/EAT ratios. RESULTS: The low ESM/EAT group (n = 353) had a higher incidence of critical outcomes (13.3% vs. 5.13%, p < 0.001) and mortality (2.55% vs. 0.69%, p = 0.019) than the high ESM/EAT group (n = 721). In multivariable analysis, the low ESM/EAT ratio was associated with critical outcomes (adjusted odds ratio [aOR] 2.11, 95% confidence interval [CI] 1.22-3.66) independently of the known COVID-19 severity factors including age, sex, body mass index (BMI), smoking history, lifestyle-related comorbidities and pneumonia volume. CONCLUSION: The low ESM/EAT ratio in COVID-19 patients can be obtained on chest CT and used to predict critical outcomes after disease onset, demonstrating the importance of detailed body composition assessments in COVID-19 practice.