SDC1 and COVID-19: Cox proportional hazard risk analysis revealed that plasma syndecan-1 at T1 (>260 ng/mL) and T3 (>461 ng/mL) were strongly associated with the 60-day mortality rate in patients with COVID-19, with a hazard ratio (HR) of 7.1 (95% CI, 2.2–22.3) (p = 0.001) and 4.6 (95%CI, 1.3–15.9) (p = 0.015), respectively (Figure 2D).