Table 4.

Predictive performance of biomarkers and their ratios at the two study gestations for preterm birth <37 weeks – Area under the ROC curves of Sensitivity vs. 1- Specificity.

Biomarkers	AUC (95% CI)	Sen	Spec	PPV	NPV	LR+	LR-	P-value
RANTES ratio	0.82 (0.62–0.94)	85	85	85	85	5.5	0.2	0.0003
GTP1	0.61 (0.44–0.77)							0.22
GTP2	0.52 (0.35–0.769)							0.80
IL 1β ratio	0.71 (0.53–0.85)	81	65	68	79	2.3	0.3	0.02
GTP1	0.57 (0.41–0.74)							0.40
GTP2	0.57 (0.41–0.73)							0.42
qFFN ratio	0.64 (0.45–0.80)	47	94	88	67	7.9	0.6	0.17
GTP1	0.67 (0.50–0.84)							0.06
GTP2	0.67 (0.50–0.84)							0.06
CL ratio	0.58 (0.40–0.75)	63	72	67	68	2.3	0.5	0.42
GTP1	0.75 (0.60–0.90)							0.005
GTP2	0.64 (0.46–0.83)							0.11
pH ratio	0.58 (0.40–0.75)	38	94	86	63	6.8	0.7	0.42
GTP1	0.53 (0.36–0.70)							0.74
GTP2	0.53 (0.35–0.71)							0.71
Combined ROC curves of GTP1/GTP2 ratios of biomarkers
IL-β ratio + RANTES ratio	0.84 (0.64–0.95)	77	92	91	80	10	0.3	0.0001
IL-β ratio + qFFN ratio	0.70 (0.51–0.85)	93	44	61	88	1.7	0.2	0.04
RANTES ratio + qFFN ratio	0.82 (0.61–0.95)	83	83	83	83	5	0.2	0.0007
IL-β ratio + RANTES ratio + qFFN ratio	0.83 (0.63–0.95)	75	92	90	79	9	0.3	0.0003

All data (i.e. both term and preterm women) were included in the analyses. AUC, area under the ROC curve; CI, confidence interval; CL, cervical length, qFFN, quantitative fetal fibronectin; PPV, positive predictive value; NPV, negative predictive value; LR+, positive likelihood ratio; LR-, negative likelihood ratio; Sen, sensitivity; Spec, specificity; GTP, gestational time point; GTP1, 20⁺⁰-22⁺⁶ weeks; GTP2, 26⁺⁰-28⁺⁶ weeks; Ratio, GTP1/GTP2.