Aspartate transferase-to-platelet ratio index-plus: A new simplified model for predicting the risk of mortality among patients with COVID-19

Table 1 Baseline demographic, clinical and laboratory characteristics of survivors and non-survivors' groups

Characteristics	Survivors, n = 328	Non-survivors, n = 25	Unadjusted OR	P value
Age in yr, median (IQR)
< 40	178 (98.89)	2 (1.11)	Ref.
40-60	112 (94.92)	6 (5.08)	4.76 (0.94-24.03)	0.05
> 60	38 (69.09)	17 (30.91)	39.81 (8.82-179.59)	0.0001
Male sex, n (%)	167 (93.30)	12 (6.70)	0.88 (0.39-2.00)	0.77
Comorbidities
Chronic kidney disease, n (%)	4 (44.44)	5 (55.56)	20.25 (5.04-81.31)	0.0001
Diabetes mellites, n (%)	55 (77.46)	16 (22.54)	8.82 (3.70-20.98)	0.0001
Chronic obstructive pulmonary disease, n (%)	55 (88.71)	7 (11.29)	1.93 (0.76-4.84)	0.16
Hypertension, n (%)	84 (84.00)	16 (16.00)	5.16 (2.19-12.12)	0.0001
Deyo-Charlson index, n (%)
0-1	267 (97.45)	7 (2.55)	Ref.
2-3	60 (80.00)	15 (20.00)	9.53 (3.72-24.40)	0.0001
> 3	1 (25.00)	3 (75.00)	114.42 (10.54-1241.77)	0.0001
Laboratory biomarkers
Hemoglobin < 12 mg/dL, n (%)	125 (92.59)	10 (7.41)	1.08 (0.47-2.48)	0.85
Total leukocytic count > 11 × 109/L, n (%)	50 (80.65)	12 (19.35)	5.13 (2.21-11.89)	0.0001
Platelet
150-350	248 (93.58)	17 (6.42)	Ref.
< 150 × 109/L, n (%)	32 (94.12)	2 (5.88)	0.91 (0.20-4.13)	0.90
> 350 × 109/L, n (%)	48 (88.89)	6 (11.11)	1.82 (0.68-4.86)	0.23
Serum AST, n (%)
< 40 U/L	239 (97.15)	7 (2.85)	Ref.
40-80 U/L	81 (84.38)	15 (15.63)	6.32 (2.49-16.05)	0.0001
> 80 U/L	8 (72.73)	3 (27.27)	12.80 (2.78-58.83)	0.001
Serum ALT, n (%)
< 40 U/L	217 (93.94)	14 (6.06)	Ref.
40-80 U/L	90 (90.00)	10 (10.00)	1.72 (0.73-4.02)	0.20
> 80 U/L	21 (95.45)	1 (4.55)	0.73 (0.09-5.89)	0.77
Serum albumin < 3.5 g/dL, n (%)	112 (86.15)	18 (13.85)	4.95 (2.01-12.22)	0.001
Serum total bilirubin > 1.5 mg/dL, n (%)	2 (40.00)	3 (60.00)	22.22 (3.52-140.03)	0.001
Serum creatinine > 1.1 mg/dL for males; > 0.95 mg/dL for females, n (%)	64 (80.00)	16 (20.00)	7.33 (3.09-17.34)	0.0001
Serum ferritin > 400 μg/L for males; > 150 μg/L for females, n (%)	169 (87.56)	24 (12.44)	22.57 (3.01-168.86)	0.002
D-dimer > 0.5 μg/mL	319 (92.73)	25 (7.27)	1	-
C-reactive protein ≥ 1 mg/L, n (%)	330 (92.70)	26 (7.30)	1	-
Creatine kinase > 117 IU/L, n (%)	0.00 (100.00)	0.00 (0.00)	-	-
APRI, n (%)
≤ 0.5	254 (95.85)	11 (4.15)	Ref.
> 0.5	74 (84.09)	14 (15.19)	4.36 (1.90-10.02)	0.001
FIB-4, n (%)
≤ 2	300 (96.15)	12 (3.85)	Ref.
> 2	17 (73.91)	6 (26.09)	8.82 (2.95-26.37)	0.0001
> 2.67	11 (61.11)	7 (38.89)	15.90 (5.24-48.24)	0.0001

Odds ratios were calculated by univariate logistic regression. Univariate logistic regression was used to calculate P value for the characteristics' differences between survivors and survivors. ALT: Alanine transferase; APRI: AST-to-platelet ratio index; AST: Aspartate transferase; CRP: C-reactive protein; FIB-4: Fibrosis-4 score; IQR: Interquartile range; OR: Odds ratio.

Table 2 Odds ratios of aspartate transferase-to-platelet ratio index associated mortality and 95% confidence intervals

	Unadjusted			Model I (Adjusted for age and sex)			Model II
APRI	OR	CI	P value	OR	CI	P value	OR	CI	P value
≤ 0.5	Ref.			Ref.			Ref.
> 0.5 - ≤ 1.5	4.36	1.90-10.02	0.001	3.23	1.29-8.12	0.01	5.03	1.63-15.52	0.005
						Covariates
						Age in yr
						< 40	Ref.
						40-60	1.75	0.25-11.89	0.56
						> 60	10.45	1.51-72.09	0.01
						Sex	1.19	0.39-3.65	0.75
						CKD	8.24	1.37-49.53	0.02
						DM	7.77	1.82-33.04	0.006
						HTN	0.25	0.05-1.11	0.07
						WBC	4.20	1.32-13.32	0.01
						Albumin	1.17	0.33-4.09	0.81
						Bilirubin	10.10	0.97-104.45	0.05
						Ferritin	12.94	1.38-121.08	0.02

Adjusted odds ratios for hospital mortality. Model 1 adjusted for age and sex; Model 2 adjusted for age, sex, diabetes mellites, chronic kidney disease, hypertension, white blood cells, serum albumin, serum total bilirubin, and serum ferritin. APRI: Aspartate transferase-to-platelet ratio index; CKD: Chronic kidney disease; CI: Confidence interval; DM: Diabetes mellites; HTN: Hypertension; IQR: Interquartile range; WBCs: White blood cells.

Table 3 Comparison of full model and aspartate transferase-to-platelet ratio index-plus in prediction of mortality among patients with coronavirus disease 2019 in the study cohort

	AUROC	HL-χ2	BIC
APRI-plus model	0.90 (95%CI: 0.86–0.95)	0.97	148.4
Full model	0.94 (95%CI: 0.90–0.98)	0.95	164.9

AUROC: Area under the receiver operating characteristic curve; BIC: Bayesian information criterion; CI: Confidence interval; HL-χ²: Hosmer-Lemeshow χ² goodness-of-fit test.