Clinical diagnosis of severe COVID-19: A derivation and validation of a prediction rule

Table 2 Demographic clinical characteristics of external validation sets

	Mild, n = 110 (%)	Severe, n = 16	P value
Age (yr)	49.0 (35.0-57.8)	70.0 (64.0-78.0)
> 60	27 (24.6)	12 (75.0)	0.000
Sex			0.007
Male	51 (46.4)	13 (81.3)
Female	59 (53.6)	3 (18.7)
BMI > 24	30 (27.3)	8 (50.0)	0.021
> 27	15 (13.6)	4 (25.0)
Onset to hospitalization (> 5 d)	37 (33.6)	15 (94.0)	0.000
Symptoms
Fever > 37.3°C	87 (79.1)	12 (75.0)	0.025
Fever > 39°C	4 (3.6)	3 (18.8)
Charlson index > 0	54 (49.1)	15 (93.8)	0.000
P/F	1 (0.9)	6 (37.5)	0.000
NLR > 2	44 (40.0)	2 (12.5)	0.000
NLR > 4	6 (5.5)	14 (87.5)
Score ≥ 7	23 (20.9)	15 (93.8)	0.000

BMI: Body mass index; P/F: PaO₂/FiO₂; NLR: Neutrophil/lymphocyte ratio.