Table 2. Diagnostic performance of soluble triggering receptor expressed on myeloid cells-1 (sTREM), midregional proatrial natriuretic peptide (proANP) and midregional proadenomedullin (proADM) biomarkers, as compared to white blood cell (WBC) count, neutrophils percentage, C reactive protein (CRP) and procalcitonin (PCT) at enrolment to predict bacterial and viral infections, according to biomarker cut-off with highest sensitivity and specificity.

Variable	n	Biomarker cut-off value	Sensitivity	Specificity	PPV	NPV	AUC (95% CI)
Probable bacterial infection (n = 235)
sTREM-1, pg/mL	405	≥69.56	31.8%	73.7%	58.1%	48.4%	0.50 (0.45–0.56)
MR-proANP, pmol/L*	408	≤59.1	76.1%	33.1%	58.3%	53.1%	0.52 (0.46–0.57)
MR-proADM, nmol/L	410	≥0.32	78.0%	35.7%	59.8%	57.0%	0.58 (0.52–0.63)
WBC count, cells/μL	428	≥12870	46.1%	61.3%	59.1%	48.3%	0.52 (0.47–0.58)
CRP mg/L	426	≥7.98	50.9%	80.4%	76.1%	57.1%	0.66 (0.61–0.71)
Neutrophils, %	413	≥61.0	63.5%	53.8%	62.1%	55.2%	0.58 (0.53–0.64)
PCT, ng/mL	265	≥0.188	67.4%	65.1%	66.4%	66.1%	0.69 (0.63–0.75)
Probable viral infection (n = 111)
sTREM-1, pg/mL*	405	≤59.28	72.2%	36.4%	29.4%	78.1%	0.52 (0.46–0.58)
MR-proANP, pmol/L*	408	≤35.5	46.2%	61.5%	29.9%	76.3%	0.51 (0.44–0.57)
MR-proADM, nmol/L*	410	≤0.31	35.8%	73.4%	32.2%	76.5%	0.53 (0.46–0.59)
WBC count, cells/μL*	428	≤15740	78.4%	33.1%	29.3%	81.2%	0.56 (0.50–0.62)
CRP, mg/L*	426	≤7.5	88.2%	46.3%	36.6%	91.8%	0.68 (0.62–0.73)
Neutrophils, %*	413	≤60.8	56.9%	60.1%	34.1%	79.4%	0.60 (0.54–0.66)
PCT, ng/mL*	265	≤0.07	48.7%	81.1%	52.0%	78.9%	0.67 (0.60–0.74)

AUC, area under the curve; 95% CI, 95% confidence interval; NPV, negative predictive value; PPV, positive predictive value.

*Inverse relationship between biomarker and probable bacterial/viral infection.