New rapid bed-side test to predict preterm delivery: phosphorylated insulin-like growth factor binding protein-1 in cervical secretions

BACKGROUND: Phosphorylated insulin-like growth factor binding protein-1 (phIGFBP-1) is secreted by decidual cells and leaks into cervical secretions when fetal membranes detach from decidua. Our aim was to assess whether detection of phIGFBP-1 in cervical secretions by a rapid bed-side test could be used to predict preterm delivery in patients with regular uterine contractions. STUDY DESIGN: In our prospective study, 36 women between 20 and 36 weeks of gestation with regular, persistent contractions (> 10/h) and 18 women between 20 and 36 weeks gestation without symptoms of preterm labor were assessed for the presence of cervical phIGFBP-1. Dacron swabs were applied to the cervix and assayed in 5 min by using immunochromotography, a new rapid bed-side test (actim partus test, Medix Biochemica, Kauniainen, Finland). Data analysis included one-way variance analysis (ANOVA), Student's t-test, chi-square and Fisher's exact test. RESULTS: Of the 36 patients with regular uterine contractions, 18 had a positive actim partus test and 18 had a negative test. Among the 18 patients with a positive test, only one delivered term and the other 17 patients delivered preterm (< 37 weeks). Among the 18 women with a negative test, only two delivered preterm (p < 0.05). Mean gestational age at delivery for patients with a positive and a negative test was 34.4 +/- 3.0 and 37.9 +/- 2.3 weeks, respectively (p < 0.05). Sensitivity, specificity, positive and negative predictive values of the rapid phIGFBP-1 test for preterm delivery was 89.5, 94.1, 94.4 and 88.9%, respectively. For delivery < 37 weeks, positive likelihood ratio was 15.2 (+/- 95% CI; range 2.6-102.5). When cervical phIGBP-1 assay was used to predict delivery within 7 days, sensitivity, specificity, positive and negative predictive values were 93.8, 85%, 83.3 and 94.1%, respectively. Positive likelihood ratio with +/- 95% CI was 6.25 (range 2.2-17.8). When patients were categorized according to cervical dilatation, the positive likelihood ratio of the test when the cervix was closed at 2 cm were 8.3 (1.3-55.3), 13.6 (2-91.4), 15.8 (2.3-106.3) and 1.5 (0.2-11.5), respectively, CONCLUSION: The presence of cervical phIGFBP-1 is predictive of preterm delivery < 37 weeks of gestation. Our study shows that cervical detection of phIGFBP-1 by immunochromotography is a rapid and easily applicable test that highly anticipates preterm delivery in patients at risk.