Accuracy of cervicovaginal fetal fibronectin test in predicting risk of spontaneous preterm birth: systematic review

Abstract

Objective: To determine the accuracy with which a cervicovaginal fetal fibronectin test predicts spontaneous preterm birth in women with or without symptoms of preterm labour.

Design: Systematic quantitative review of studies of test accuracy.

Data sources: Medline, Embase, PASCAL, Biosis, Cochrane Library, Medion, National Research Register, SCISEARCH, conference papers, manual searching of bibliographies of known primary and review articles, and contact with experts and manufacturer.

Study selection: Two reviewers independently selected and extracted data on study characteristics, quality, and accuracy.

Data extraction: Accuracy data were used to form 2x2 contingency tables with spontaneous preterm birth before 34 and 37 weeks' gestation and birth within 7-10 days of testing (for symptomatic pregnant women) as reference standards. Data were pooled to produce summary receiver operating characteristic curves and summary likelihood ratios for positive and negative test results.

Data synthesis: 64 primary articles were identified, consisting of 28 studies in asymptomatic women and 40 in symptomatic women, with a total of 26 876 women. Among asymptomatic women the best summary likelihood ratio for positive results was 4.01 (95% confidence interval 2.93 to 5.49) for predicting birth before 34 weeks' gestation, with corresponding summary likelihood ratio for negative results of 0.78 (0.72 to 0.84). Among symptomatic women the best summary likelihood ratio for positive results was 5.42 (4.36 to 6.74) for predicting birth within 7-10 days of testing, with corresponding ratio for negative results of 0.25 (0.20 to 0.31).

Conclusion: Cervicovaginal fetal fibronectin test is most accurate in predicting spontaneous preterm birth within 7-10 days of testing among women with symptoms of threatened preterm birth before advanced cervical dilatation.

Figure 1

Study selection process for systematic review of cervicovaginal fetal fibronectin test see webextra for list of excluded studies (total number of studies (68) exceeds 64 because some primary articles provided data on more than one study)

Figure 2

Methodological quality of studies included in the systematic review. Data presented as 100% stacked bars; figures in the stacks represent number of studies

Figure 3

Summary receiver operating characteristic (ROC) curves for cervicovaginal fetal fibronectin test in predicting spontaneous preterm birth in asymptomatic women

Figure 4

ROC curve (with 95% confidence interval boundaries) for individual study results for test predicting spontaneous preterm birth at 34 weeks' gestation in asymptomatic women

Figure 5

ROC curve (with 95% confidence interval boundaries) for individual study results for test predicting spontaneous preterm birth at 37 weeks' gestation in asymptomatic women

Figure 6

Pooled estimates of likelihood ratios for cervicovaginal fetal fibronectin test and their impact on predictive probabilities of spontaneous preterm birth in asymptomatic and symptomatic women (as for ROC if this pooled one is kept in short can refer to sep forest plots in long version)

Figure 7

Likelihood ratios for positive and negative test results for studies predicting spontaneous preterm birth before 34 weeks' gestation in asymptomatic women

Figure 8

Likelihood ratios for positive and negative test results for studies predicting spontaneous preterm birth before 37 weeks' gestation in asymptomatic women

Figure 9

Summary receiver operating characteristic (ROC) curves and areas for cervicovaginal fetal fibronectin test in predicting spontaneous preterm birth symptomatic women

Figure 10

ROC curve (with 95% confidence interval boundaries) for individual study results for cervicovaginal fetal fibronectin test in predicting spontaneous preterm birth 7-10 days after testing in symptomatic women

Figure 11

ROC curve (with 95% confidence interval boundaries) for individual study results for cervicovaginal fetal fibronectin test in predicting spontaneous preterm birth before 34 weeks' gestation in symptomatic women

Figure 12

ROC curve (with 95% confidence interval boundaries) for individual study results for cervicovaginal fetal fibronectin test in predicting spontaneous preterm birth before 37 weeks' gestation in symptomatic women

Figure 13

Likelihood ratios for positive and negative test results for studies predicting spontaneous preterm birth 7-10 days after testing in symptomatic women

Figure 14

Likelihood ratios for positive and negative test results for studies predicting spontaneous preterm birth before 34 weeks' gestation in symptomatic women

Figure 15

Likelihood ratios for positive and negative test results for studies predicting spontaneous preterm birth before 37 weeks' gestation in symptomatic women