Table 3.

Algorithm to estimate risk for hospital mortality using total points for risk scores with logistic regression analysis in the severe patients with COVID-19 from training dataset

Variables	Categories	Reference value (Wij)	Bi	Regression units Βi (Wij—WiREF)	Points assigned Βi (Wij—WiREF)/B
NSL risk score (NE +  SaO2 + LDH)
NE (%)			0.127
	≤ 60	55 (WiREF)		0.000	0
	60.1–70	65		1.270	4
	70.1–80	75		2.540	8
	80.1–90	85		3.810	12
	≥ 90.1	95		5.080	16
SaO2 (%)			-0.175
	100–96	98 (WiREF)		0.000	0
	95–91	93		0.875	3
	90–86	88		1.750	6
	≤ 85	83		2.625	9
LDH (U/L)			0.003
	≤ 221	171 (WiREF)		0.000	0
	222–321	271		0.300	1
	322–421	371		0.600	2
	422–521	471		0.900	3
	522–621	571		1.200	4
	622–721	671		1.500	5
	722–821	771		1.800	6
	822–921	871		2.100	7
	922–1021	971		2.400	8
	≥ 1022	1071		2.700	9
NL risk score (NE + LDH)
NE (%)			0.158
	≤ 60	55 (WiREF)		0.000	0
	60.1–70	65		1.580	4
	70.1–80	75		3.160	8
	80.1–90	85		4.740	12
	≥ 90.1	95		6.320	16
LDH (U/L)			0.004
	≤ 221	171 (WiREF)		0	0
	222–321	271		0.400	1
	322–421	371		0.800	2
	422–521	471		1.200	3
	522–621	571		1.600	4
	622–721	671		2.000	5
	722–821	771		2.400	6
	822–921	871		2.800	7
	922–1021	971		3.200	8
	≥ 1022	1071		3.600	9

Wij, reference value for each category of risk factors in risk score; WiREF, the base category for each risk factor was used as the basic value for that factor and assigned 0 point. Bi, the regression coeffcient of each risk factor from logistic regression; B, the smallest regression units or the smallest units divided by some constant (B = 0.3 for NSL risk score and B = 0.4 for NL risk score)