Accuracy of a combined insulin-like growth factor-binding protein-1/interleukin-6 test (Premaquick) in predicting delivery in women with threatened preterm labor

To determine values of combinations of interleukin-6 (IL-6)/cervical native insulin-like growth factor-binding protein-1 (IGFBP-1)/total IGFBP-1 (Premaquick) in predicting spontaneous deliveries and spontaneous exclusive preterm deliveries in women with threatened preterm labor. Women with singleton pregnancies between gestation age (GA) of 24 weeks and 36 weeks and 6 days with preterm labor were recruited during a prospective multicenter study. Premaquick was positive when at least two of three biomarkers were positive. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were estimated for both prediction of spontaneous deliveries and spontaneous exclusive preterm deliveries. Ninety-seven (99.0%) out of 98 women enrolled were analyzed. Based on delivery status 7/14 days post-enrollment of general study population, Premaquick had a sensitivity of 87.1/85.7%, a specificity of 92.4/96.8%, a PPV of 84.4/93.8% and a NPV of 93.9/92.3% for prediction of spontaneous delivery. Predictive accuracy of Premaquick test in relation to days of enrollment were: 90.7% (≤7 days) and 92.8% (≤14 days). For women enrolled at GA <35 weeks, Premaquick had a sensitivity of 100.0/87.5%, a specificity of 94.1/96.9%, a PPV of 70.5/87.5%, a NPV of 100.0/96.9% and an accuracy of 95.0/95.0% for prediction of preterm delivery within 7/14 days of enrollment, respectively. PPV was most significantly different in both groups when outcomes were compared between 2 days and 14 days post-enrollment (P<0.001). This novel triple biomarker model of native and total IGFBP-1 and IL-6 appears to be an accurate test in predicting spontaneous deliveries and spontaneous exclusive preterm deliveries in threatened preterm labor in singleton pregnancies.