Development of a novel score for the diagnosis of bacterial infection in patients with acute-on-chronic liver failure

Table 1 Baseline characteristics of the patients

	Non-infected (n = 217)	Infected (n = 169)	P value
Age (yr)	45.96 ± 13.94	52.18±14.70	< 0.001
Male, n (%)	177 (81.6)	126 (74.6)	0.096
Etiology, n (%)			0.051
HBV infection	173 (79.7)	114 (67.5)
Alcohol	17 (7.8)	23 (13.6)
HBV and alcohol	8 (3.7)	8 (4.7)
Others	19 (8.8)	24 (14.2)
MELD score	18.94 ± 4.39	22.24 ± 7.36	< 0.001
PT (s)	21.97 ± 6.52	26.22 ± 9.90	< 0.001
INR	1.90 ± 0.56	2.35 ± 1.16	< 0.001
Total bilirubin (μmol/L)	272.56 ± 127.41	317.70 ± 153.10	0.001
Albumin (g/L)	31.34 ± 4.76	28.81 ± 5.36	< 0.001
ALT (U/L)	663.30 ± 694.59	524.97 ± 800.98	0.070
AST (U/L)	463.18 ± 494.97	477.25 ± 662.96	0.811
GGT (U/L)	159.74 ± 160.13	141.85 ± 143.03	0265
Creatinine (μmol/L)	61.67 ± 19.37	81.71 ± 56.61	< 0.001
PCT (ng/mL)	0.75 ± 0.60	1.46 ± 1.81	< 0.001
CRP (mg/L)	15.86 ± 9.61	25.59 ± 17.50	< 0.001
WBC (× 109/L)	6.67 ± 3.11	9.01 ± 5.62	< 0.001
N%	66.80 ± 10.57	73.03 ± 11.56	< 0.001

PT: Prothrombin time; INR: International normalized ratio; ALT: Alanine aminotransferase; AST: Aspartate transaminase; GGT: Gamma-glutamyl transferase; PCT: Procalcitonin; CRP: C-reactive protein; WBC: White blood cell count; N%: Proportion of neutrophils.

Table 2 Procalcitonin levels in relation to different infection sites

	PCT (ng/mL)	CRP (mg/L)	WBC (× 109/L)	N%
Overall (n = 169)	1.46 ± 1.81	25.59 ± 17.50	9.01 ± 5.62	73.03 ± 11.56
Pneumonia (n = 94)	1.35 ± 1.77	25.26 ± 17.80	8.87 ± 5.98	71.77 ± 11.23
SBP (n = 23)	1.29 ± 0.83	18.55 ± 9.19	8.46 ± 3.88	72.05 ± 14.06
Pneumonia and SBP (n = 21)	2.30 ± 2.83	37.71 ± 24.00	11.30 ± 6.72	77.26 ± 13.85
Infection without identified source (n = 13)	2.12 ± 2.04	29.26 ± 11.98	9.35 ± 4.81	75.57 ± 10.87
Biliary tract (n = 12)	0.59 ± 0.37	14.61 ± 8.12	7.92 ± 4.66	73.42 ± 10.25
Urinary (n = 10)	0.74 ± 0.54	19.72 ± 5.90	5.38 ± 2.43	67.43 ± 9.25
Bloodstream (n = 3)	1.02 ± 0.42	32.65 ± 17.90	8.21 ± 1.13	74.67 ± 5.80
P value	0.084	0.001	0.203	0.406

SBP: Spontaneous bacterial peritonitis; PCT: Procalcitonin; CRP: C-reactive protein; WBC: White blood cell count; N%: Proportion of neutrophils.

Table 3 Diagnostic accuracy of procalcitonin, C-reactive protein, white blood cells, and proportion of neutrophils for the diagnosis of infection in liver failure

	Cut offs	Sensitivity (%)	Specificity (%)	PLR	NLR	PPV (%)	NPV (%)	P value	AUROC
PCT	≥ 1.01	42.60	78.80	2.01	0.73	61.01	63.81	< 0.0001	0.637
CRP	≥ 17.5	63.91	67.28	1.95	0.54	60.33	70.54	< 0.0001	0.692
WBC	≥ 7.90	47.93	79.72	2.36	2.36	64.79	66.28	< 0.0001	0.638
N%	≥ 73.8	55.03	76.50	2.34	0.59	64.58	68.60	< 0.0001	0.674

PCT: Procalcitonin; CRP: C-reactive protein; WBC: White blood cell count; N%: Proportion of neutrophils; PLR: Positive likelihood ratio; NLR: Negative likelihood ratio; PPV: Positive predictive value; NPV: Negative predictive value; AUROC: Area under the receiver operating characteristic curve.

Table 4 The infection scoring system

Items	Definition	Score
N%	< 60	0
	70 > N ≥ 60	1
	80 > N ≥ 70	2
	≥ 80	3
PCT	< 0.5	0
	1 > PCT ≥ 0.5	1
	2 > PCT ≥ 1	2
	≥ 2	3
CRP	< 10	0
	20 >N ≥ 10	1
	≥ 20	2

PCT: Procalcitonin; CRP: C-reactive protein; N%: Proportion of neutrophils.

Table 5 Diagnostic value of the infection score

Score	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	PLR	NLR
≥ 2	98.22	22.12	49.55	94.10	1.26	0.08
≥ 4	78.05	55.29	57.91	76.16	1.75	0.40
≥ 6	26.63	91.24	70.30	61.49	3.04	0.80
≥ 8	6.51	99.54	91.68	57.76	14.12	0.94

PPV: Positive predictive value; NPV: Negative predictive value; PLR: Positive likelihood ratio; NLR: Negative likelihood ratio.