Comparison of rapid bedside tests for phosphorylated insulin-like growth factor-binding protein 1 and fetal fibronectin to predict preterm birth

Abstract

ObjectiveTo compare the accuracy of rapid bedside tests for phosphorylated insulin-like growth factor-binding protein 1 (phIGFBP-1) and fetal fibronectin (fFN) to predict preterm delivery among women with threatened preterm labor. MethodsA prospective observational study was conducted among women with a singleton pregnancy of 28–36 weeks, intact membranes, and symptoms suggestive of preterm labor who attended a center in New Delhi, India, between April 1, 2011, and March 31, 2014. Rapid bedside tests were performed at presentation to measure the levels of phIGFBP-1 and fFN in cervicovaginal secretions. All patients were managed as per the standard hospital protocol and followed up until delivery. ResultsData were available for 468 participants. For delivery before 37 weeks, the phIGFBP-1 test exhibited a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 81.1%, 97.1%, 95.2% and 87.7%, respectively. The sensitivity, specificity, PPV, and NPV for the fFN test were 19.4%, 99.4%, 97.4%, and 63.2%, respectively. The phIGFBP-1 test displayed higher sensitivity and NPV than did the fFN test for delivery before 34 weeks and within 7 days of testing (P<0.05 for all). ConclusionThe rapid bedside test for phIGFBP-1 was more reliable in the prediction of preterm delivery than was the equivalent test for fFN.