111 patients with SARS-CoV-2 ARDS and 29 patients with CAP-ARDS met the inclusion criteria (Table 1). Many patients (n=33) screened for CAP-ARDS were excluded, as ARDS had developed >48 hours after hospital admission. Patient demographic details are shown in table 1, with both groups being broadly similar except for ethnic background. A greater proportion of SARS-CoV-2 patients were of Asian / Asian British ethnicity (p=0.002), and a lower proportion were of White ethnicity (0.012), compared to CAP-ARDS patients
On ICU admission, SARS-CoV-2 patients had significantly lower APACHE-II and SOFA scores than CAP-ARDS patients (see table 1: p<0.0001). SOFA scores remained lower in SARS-CoV-2 patients for 7 days following ICU admission (Figure 1A).
SARS-CoV-2 patients had lower circulating leukocytes, neutrophils and monocytes (p<0.0001 for all) than CAP-ARDS patients on ICU admission. Leukocytes and neutrophil counts remained lower in SARS-CoV-2 patients for 3 days following ICU admission, whereas monocyte counts remained lower for 6 days (Figures 1B-D). Albumin was lower (p=0.003) whilst CRP (p=0.016) and platelet count (p=0.029) were higher at ICU admission in SARS-CoV-2 patients. Differences in CRP and albumin between patient groups increased with duration of ICU stay (Figures 1E-F). There was no difference in lymphocytes, eosinophils, bilirubin or creatinine between groups on ICU admission.
Peak end-expiratory pressure (PEEP) was higher in SARS-CoV-2 patients on ICU admission (p=0.003). However, there was no difference in other ventilator parameters between groups on ICU admission, including driving pressure, peak inspiratory pressure and PaO2 / FiO2 ratio. SARS-CoV-2 patients required a lower dose of vasopressors on ICU admission (p=0.016).
SARS-CoV-2 patients required a longer duration of mechanical ventilation compared to CAP-ARDS patients (p=0.010). However, there was no significant difference in other major ICU outcomes between groups, including hospital mortality, ICU length of stay, time to death from ICU admission, development of moderate / severe ARDS, need for renal replacement therapy or need for tracheostomy.