Development and Validation of a Nomogram for Predicting the Risk of Coronavirus-Associated Acute Respiratory Distress Syndrome: A Retrospective Cohort Study

Figures & data

Table 1 Baseline Characteristics of Patients in Training Cohort and Validation Cohort

Variables	Training Cohort (N = 197)	Validation Cohort (N = 64)	P value
Age	63 (54, 71)	63 (53.25, 70)	0.883
Gender
Women	99 (50.25%)	40 (63.49%)	0.088
Men	98 (49.75%)	24 (36.51%)
Basic disease
Cardiopathy disease	173 (87.82%)	55 (85.94%)	0.916
Diabetes	159 (80.71%)	51 (79.69%)	0.757
Hypertension	126 (63.96%)	39 (60.94%)	0.66
Cerebrovascular disease	5 (2.54%)	3 (4.69%)	0.359
COPD	7 (3.55%)	5 (7.81%)	0.168
Symptoms
Sore throat	166 (84.26%)	56 (87.5%)	0.949
Expectoration	95 (48.22%)	27 (42.19%)	0.432
Cough	39 (19.8%)	10 (15.63%)	0.448
Fever	41 (20.81%)	13 (20.31%)	0.903
Disease type
Non-severe	93 (47.21%)	28 (43.75%)	0.32
Severe	104 (52.79%)	36 (56.25%)
Laboratory results
FPG, mmol/L	5.87 (5.09, 7.37)	5.75 (5.06, 6.86)	0.452
CRP, mg/L	10 (2.3, 40.55)	11.75 (1.7, 32.95)	0.779
White blood cell count, ×10^9 /L	5.44 (4.6, 7.02)	6.61 (4.71, 8.14)	0.021
Lymphocyte count, ×10^9 /L	1.23 (0.9, 1.65)	1.42 (0.89, 1.86)	0.297
Platelet count, ×10^9/L	232 (176.5, 318)	256.5 (193.5, 310.75)	0.305
ALT, U/L	27 (17, 52)	32 (18, 75)	0.269
AST, U/L	25 (19, 38)	28 (20.25, 54.75)	0.115
Albumin, g/L	36.45±5.02	36.7±4.53	0.722
Scr, μmol/L	68 (56, 82.5)	66.5 (59, 79)	0.846
BUN, mmol/L	4.4 (3.65, 5.3)	4.35 (3.23, 5.65)	0.563
D-dimer, μg/mL	0.82 (0.43, 2.22)	1.32 (0.35, 3.53)	0.443
cTnI, pg/mL	4 (1.9, 11.4)	5.05 (2.23, 14.53)	0.101
IL-6, pg/mL	6.02 (2.41, 40.69)	11.15 (3.48, 47.09)	0.158
LDH, U/L	265 (198.5, 304)	273 (182, 275.3)	0.391
NLR, %	1.87 (2.92, 4.51)	1.69 (2.05, 3.97)	0.383
ARDS
ARDS	32 (16.24%)	10 (15.63%)	0.907
Non-ARDS	165 (83.76%)	54 (85.38%)

Abbreviations: COPD, chronic obstructive pulmonary disease; FPG, fasting plasma glucose; CRP, C-reactive protein; ALT, Alanine aminotransferase; AST, Aspartate aminotransferase; Scr, Serum creatinine; BUN, urea nitrogen; cTnI, cardiac troponin I; LDH, lactate dehydrogenase; NLR, neutrophil-to-lymphocyte ratio; ARDS, acute respiratory distress syndrome.

Table 2 Univariate and Multivariable Logistic Regression Analysis of the Training Cohort

Variables	Univariate		Multivariate
	OR (95% CI)	P value	OR (95% CI)	P value
Age	5.35 (2.5, 11.44)	<0.001
Gender	0.851 (0.399, 1.816)	0.676
Basic disease
Cardiopathy disease	0.685 (0.234, 2.001)	0.489
Diabetes	0.818 (0.324, 2.067)	0.671
Hypertension	0.514 (0.239, 1.105)	0.088
Cerebrovascular disease	0.276 (0.044, 1.729)	0.169
COPD	0.489 (0.09, 2.653)	0.407
Symptoms
Sore throat	1.992 (0.566, 7.015)	0.283
Expectoration	0.844 (0.381, 1.869)	0.675
Cough	0.916 (0.349, 2.408)	0.859
Fever	1.062 (0.424, 2.664)	0.897
Laboratory results
FPG, mmol/L	6.11 (1.83, 20.44)	0.003	12.67 (2.66, 60.26)	0.001
CRP, mg/L	7.64 (3.47, 16.83)	<0.001
White blood cell count, ×10^9 /L	2.38 (1.18, 4.81)	0.016
Lymphocyte count, ×10^9 /L	0.13 (0.06, 0.26)	<0.001
Platelet count, ×10^9/L	0.21 (0.1, 0.41)	<0.001	0.32 (0.11, 0.94)	0.038
ALT, U/L	2.66 (1.35, 5.22)	0.005
AST, U/L	6.15 (3.05, 12.42)	<0.001
Albumin, g/L	0.29 (0.15, 0.57)	<0.001
Scr, μmol/L	2.9 (1.45, 5.8)	0.003
BUN, mmol/L	5.24 (2.62, 10.49)	<0.001
D-dimer, μg/mL	11.26 (4.93, 25.71)	<0.001	5.1 (1.69, 15.39)	0.004
cTnI, pg/mL	59.7 (22.43, 158.9)	<0.001	42.93 (14.23, 129.54)	<0.001
IL-6, pg/mL	10.21 (4.32, 24.1)	<0.001
LDH, U/L	4.2 (2, 8.78)	<0.001
NLR, %	6.2 (3.05, 12.61)	<0.001

Note: P value in bold means one less than 0.05.

Figure 1 ROC curves of the nomogram, FPG, PLT, D-dimer, and cTnI in the training and validation cohorts. (A) ROC curve in training cohort. (B) ROC curve in validation cohort.

Figure 2 The nomogram predicts the probability of hospitalized COVID-19 patients progressing to ARDS. The score for each value is assigned by drawing a line upward to the points line, and the sum of the four scores is plotted on the Total points line.

Figure 3 Calibration plots for predicting the rate of ARDS in the training and validation cohort. (A) Calibration plot in training cohort. (B) Calibration plot in validation cohort.

Figure 4 The decision curves analysis curves for nomogram in the training and validation cohort. (A) DCA curve in training cohort. (B) DCA curve in validation cohort.