Background: Skeletal muscle depletion is common in the elderly and individuals with chronic comorbidities, who have an increased risk of developing severe coronavirus disease 2019 (COVID-19), which is defined by hypoxia requiring supplemental oxygen. This study aimed to determine the association between skeletal muscle depletion and clinical outcomes in patients with severe COVID-19.
Methods: One hundred and sixteen patients with severe COVID-19 who underwent chest computed tomography (CT) scan on admission were included in this multicentre, retrospective study. Paraspinal muscle index (PMI) and radiodensity (PMD) were measured using CT images. The primary composite outcome was the occurrence of critical illness (respiratory failure requiring mechanical ventilation, shock, or intensive care unit admission) or death, and the secondary outcomes were the duration of viral shedding and pulmonary fibrosis in the early rehabilitation phase. Logistic regression and Cox proportional hazards models were employed to evaluate the associations.
Results: The primary composite outcome occurred in 48 (41.4%) patients, who were older and had lower PMD (both P < 0.05). Higher PMD was associated with reduced risk of critical illness or death in a fully adjusted model overall (OR per SD increment: 0.87, 95% CI: 0.80-0.95; P = 0.002) and in female patients (OR per SD increment: 0.71, 95% CI: 0.56-0.91; P = 0.006), although the effect was not statistically significant in male patients (P = 0.202). Higher PMD (HR per SD increment: 1.08, 95% CI: 1.02-1.14; P = 0.008) was associated with shorter duration of viral shedding among female survivors. However, no significant association was found between PMD and pulmonary fibrosis in the early rehabilitation phase, or between PMI and any outcome in both men and women.
Conclusion: Higher PMD, a proxy measure of lower muscle fat deposition, was associated with a reduced risk of disease deterioration and decreased likelihood of prolonged viral shedding among female patients with severe COVID-19.
Keywords: Clinical outcome; Computed tomography; Coronavirus disease 2019; Paraspinal muscle measurement; Severe pneumonia.
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