3.2 Patient characteristics
Enrolled patients exhibited a median age of 61.0 years, and were 54.5% (603/1107) male. The most prevalent comorbidities in these patients included cardiovascular disease (22.7%, 251/1107), diabetes mellitus (13.4%, 148/1107), and cerebrovascular disease (10.3%, 114/1107). Upon admission, 42.4% (462/1089) of patients presented with lymphocytes < 0.8×109/L, 49.1% (515/1048) presented with PaO2/FiO2 < 300 mmHg, 11.7% (129/1107) presented with confusion, and 14.4% (159/1107) presented with a respiratory rate ≥ 30 breaths/min (Table 1).
In total, 33.5% (371/1107) patients were found to be co-infected with other community-acquired pathogens, including Klebsiella pneumoniae (32.6%, 121/371), Streptococcus pneumoniae (29.9%, 111/371), and Staphylococcus aureu s (19.79%, 73/371) (Supplementary Material 4).
Of these patients, 33.5% (391/1107) underwent NAI treatment within 48 h following symptom onset, while 12.7% (141/1107) were administered systemic corticosteroids before IMV following admission. Non-invasive mechanical ventilation (NIMV) and IMV were respectively conducted within 14 days of admission for 11.6% (128/1107) and 10.6% (117/1107) of patients. The all-cause 14-day mortality rate for these patients was 3.2% (35/1107) (Table 1).
The baseline clinical characteristics and outcomes between patients in the derivation and validation cohorts were similar (Supplementary Material 5).