Ultrasonographic abdominal visceral fat thickness as an independent predictive factor of mortality in COVID-19 patients; a prospective cohort study

Background: Visceral fat has been associated with severe COVID-19 outcomes due to its pro-inflammatory effects. While computed tomography (CT) is the standard for measuring visceral fat, ultrasound (US) offers a non-invasive and accessible alternative. This study aimed to evaluate whether abdominal fat thickness measured via US predicts clinical outcomes in COVID-19 pneumonia. Method: This prospective cohort study included 83 hospitalized COVID-19 patients. Visceral fat thickness (VFT), subcutaneous fat thickness (SFT), and preperitoneal fat thickness (PFT) was measured with US. The primary outcome of interest was mortality. Multivariable logistic regression was used to analyze associations, adjusting for confounders such as age, sex and comorbidities. Results: 83 patients with the median age of 62 (IQR: 49–73) years were included (53% male). Mortality was significantly higher in male (61.4% vs. 38.6%, p = 0.018); older age (73.5 vs. 59.5; p = 0.003); patients with lower median blood oxygen saturation (80% vs. 88%, p < 0.001), higher median levels of AST (66 vs. 39.5, p = 0.002), BUN (67 vs. 36.5, p < 0.001), and creatinine (1.6 vs. 1.2, p < 0.001); and patients under mechanical ventilation (p < 0.01). Based on multivariate logistic regression analysis the independent predictors of mortality were VFT (aOR: 1.025, 95% CI: 1.001–1.051, p = 0.047), old age (aOR: 1.064, 95% CI: 1.016–1.115, p = 0.008), and male sex (aOR: 4.430, 95% CI: 1.169–16.769, p = 0.029). In contrast, SFT had an aOR of 1.059 (95% CI: 0.966–1.161, p = 0.223), and PFT had an aOR of 1.016 (95% CI: 0.880–1.172, p = 0.830), neither of which were statistically significant. The area under the ROC curve of VFT in predicting mortality was 0.643. The optimal cutoff value for VFT, determined using the Youden Index, was 80.4. At this cutoff point, the sensitivity was 52.2% while the specificity was 75.0%. Conclusion: It seems that, ultrasound-measured VFT is a potential predictor of mortality in hospitalized COVID-19 patients, offering a cost-effective and accessible tool for risk assessment. Further research is needed to confirm its broader applicability.