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Objective: To evaluate the cost-effectiveness of combining cervical-length (CL) measurement and fetal fibronectin (fFN) testing in women with symptoms of preterm labor between 24 and 34 weeks' gestation., Methods: This was a model-based cost-effectiveness analysis evaluating seven test-treatment strategies based on CL measurement and/or fFN testing in women with symptoms of preterm labor from a societal perspective, in which neonatal outcomes and costs were weighted. Estimates of disease prevalence, test accuracy and costs were based on two recently performed nationwide cohort studies in The Netherlands., Results: Strategies using fFN testing and CL measurement separately to predict preterm delivery are associated with higher costs and incidence of adverse neonatal outcomes compared with strategies that combine both tests. Additional fFN testing when CL is 15-30 mm was considered cost effective, leading to a cost saving of €3919 per woman when compared with a treat-all strategy, with a small deterioration in neonatal health outcomes, namely one additional perinatal death and 21 adverse outcomes per 10 000 women with signs of preterm labor (incremental cost-effectiveness ratios €39 million and €1.9 million, respectively). Implementing this strategy in The Netherlands, a country with about 180 000 deliveries annually, could lead to an annual cost saving of between €2.4 million and €7.6 million, with only a small deterioration in neonatal health outcomes., Conclusion: In women with symptoms of preterm labor at 24-34 weeks' gestation, performing additional fFN testing when CL is between 15 and 30 mm is a viable and cost-saving strategy. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd., (Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.)

Objective: Analysis of national implementation of the foetal fibronectin test in the diagnostics of threatened preterm labour in the Netherlands, and indication of the possible obstacles and consequences of implementation or no implementation., Design: National questionnaire, retrospective cohort study and cost-effectiveness calculation., Methods: We approached all hospitals in the Netherlands (n = 86) with a questionnaire on use of the fibronectin test. We also collected data on women who were referred to the Academic Medical Center (AMC), a tertiary care centre in Amsterdam, with symptoms of threatened preterm labour. We investigated whether the referred patients gave birth within 7 days, and whether unnecessary transfer to a centre with a neonatal intensive care unit (NICU) could have been avoided by implementation of the fibronectin test in the referring hospital., Results: The fibronectin test was used in 34% of the hospitals and an additional 17% were in the process of implementation. The most important reasons not to use the fibronectin test were of a financial nature (50%). The cohort study included 96 women who were referred from secondary care. In our cohort, 36% of all transfers could have been avoided by implementation of the fibronectin test in secondary care., Conclusion: The fibronectin test can greatly reduce overtreatment and unnecessary transfer in threatened preterm labour, but implementation remains limited. Costs of the test are an obstacle for the referring hospitals, while implementation prevents unnecessary transport, admission and treatment of pregnant women, giving a potential saving of at least EUR 1,027,930 per year. Inclusion in the Netherlands Society for Obstetrics and Gynaecology (Nederlandse Vereniging voor Obstetrie en Gynaecologie, NVOG) guidelines would be a first step towards wider implementation. Slow implementation exemplifies a more widespread problem: the current reimbursement system does not stimulate such cost-saving innovations.

Objective  We assessed the influence of external factors on false-positive, false-negative, and invalid fibronectin results in the prediction of spontaneous delivery within 7 days. Methods  We studied symptomatic women between 24 and 34 weeks' gestational age. We performed uni- and multivariable logistic regression to estimate the effect of external factors (vaginal soap, digital examination, transvaginal sonography, sexual intercourse, vaginal bleeding) on the risk of false-positive, false-negative, and invalid results, using spontaneous delivery within 7 days as the outcome. Results  Out of 708 women, 237 (33%) had a false-positive result; none of the factors showed a significant association. Vaginal bleeding increased the proportion of positive fetal fibronectin (fFN) results, but was significantly associated with a lower risk of false-positive test results (odds ratio [OR], 0.22; 95% confidence intervals [CI], 0.12-0.39). Ten women (1%) had a false-negative result. None of the investigated factors was significantly associated with a significantly higher risk of false-negative results. Twenty-one tests (3%) were invalid; only vaginal bleeding showed a significant association (OR, 4.5; 95% CI, 1.7-12). Conclusion  The effect of external factors on the performance of qualitative fFN testing is limited, with vaginal bleeding as the only factor that reduces its validity., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Background: The combination of the qualitative fetal fibronectin test and cervical length measurement has a high negative predictive value for preterm birth within 7 days; however, positive prediction is poor. A new bedside quantitative fetal fibronectin test showed potential additional value over the conventional qualitative test, but there is limited evidence on the combination with cervical length measurement., Objective: The purpose of this study was to compare quantitative fetal fibronectin and qualitative fetal fibronectin testing in the prediction of spontaneous preterm birth within 7 days in symptomatic women who undergo cervical length measurement., Study Design: We performed a European multicenter cohort study in 10 perinatal centers in 5 countries. Women between 24 and 34 weeks of gestation with signs of active labor and intact membranes underwent quantitative fibronectin testing and cervical length measurement. We assessed the risk of preterm birth within 7 days in predefined strata based on fibronectin concentration and cervical length., Results: Of 455 women who were included in the study, 48 women (11%) delivered within 7 days. A combination of cervical length and qualitative fibronectin resulted in the identification of 246 women who were at low risk: 164 women with a cervix between 15 and 30 mm and a negative fibronectin test (<50 ng/mL; preterm birth rate, 2%) and 82 women with a cervix at >30 mm (preterm birth rate, 2%). Use of quantitative fibronectin alone resulted in a predicted risk of preterm birth within 7 days that ranged from 2% in the group with the lowest fibronectin level (<10 ng/mL) to 38% in the group with the highest fibronectin level (>500 ng/mL), with similar accuracy as that of the combination of cervical length and qualitative fibronectin. Combining cervical length and quantitative fibronectin resulted in the identification of an additional 19 women at low risk (preterm birth rate, 5%), using a threshold of 10 ng/mL in women with a cervix at <15 mm, and 6 women at high risk (preterm birth rate, 33%) using a threshold of >500 ng/mL in women with a cervix at >30 mm., Conclusion: In women with threatened preterm birth, quantitative fibronectin testing alone performs equal to the combination of cervical length and qualitative fibronectin. Possibly, the combination of quantitative fibronectin testing and cervical length increases this predictive capacity. Cost-effectiveness analysis and the availability of these tests in a local setting should determine the final choice., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objective: To evaluate whether in symptomatic women, the combination of quantitative fetal fibronectin (fFN) testing and cervical length (CL) improves the prediction of preterm delivery (PTD) within 7 days compared with qualitative fFN and CL., Design: Post hoc analysis of frozen fFN samples of a nationwide cohort study., Setting: Ten perinatal centres in the Netherlands., Population: Symptomatic women between 24 and 34 weeks of gestation., Methods: The risk of PTD <7 days was estimated in predefined CL and fFN strata. We used logistic regression to develop a model including quantitative fFN and CL, and one including qualitative fFN (threshold 50 ng/ml) and CL. We compared the models' capacity to identify women at low risk (<5%) for delivery within 7 days using a reclassification table., Main Outcome Measures: Spontaneous delivery within 7 days after study entry., Results: We studied 350 women, of whom 69 (20%) delivered within 7 days. The risk of PTD in <7 days ranged from 2% in the lowest fFN group (<10 ng/ml) to 71% in the highest group (>500 ng/ml). Multivariable logistic regression showed an increasing risk of PTD in <7 days with rising fFN concentration [10-49 ng/ml: odds ratio (OR) 1.3, 95% confidence interval (95% CI) 0.23-7.0; 50-199 ng/ml: OR 3.2, 95% CI 0.79-13; 200-499 ng/ml: OR 9.0, 95% CI 2.3-35; >500 ng/ml: OR 39, 95% CI 9.4-164] and shortening of the CL (OR 0.86 per mm, 95% CI 0.82-0.90). Use of quantitative fFN instead of qualitative fFN resulted in reclassification of 18 (5%) women from high to low risk, of whom one (6%) woman delivered within 7 days., Conclusion: In symptomatic women, quantitative fFN testing does not improve the prediction of PTD within 7 days compared with qualitative fFN testing in combination with CL measurement in terms of reclassification from high to low (<5%) risk, but it adds value across the risk range., Tweetable Abstract: Quantitative fFN testing adds value to qualitative fFN testing with CL measurement in the prediction of PTD., (© 2015 Royal College of Obstetricians and Gynaecologists.)

Objective: To compare the accuracy of the Actim Partus test and fetal fibronectin (fFN) test in the prediction of spontaneous preterm delivery within seven days in symptomatic women undergoing cervical length measurement., Study Design: We performed a post-hoc analysis on frozen samples of a nationwide cohort study in all 10 perinatal centres in the Netherlands. We selected samples from women with signs of preterm labour between 24 and 34 weeks of gestational age and a cervical length below 30mm. Delivery within seven days after initial assessment was the primary endpoint. We calculated sensitivity, specificity, and positive and negative predictive values for the combination of both the Actim Partus test and fFN test with cervical length. A test was considered positive in case of a cervical length between 15 and 30mm with a positive Actim Partus or fFN test, and a cervical length below 15mm regardless the test result., Results: In total, samples of 350 women were tested, of whom 69 (20%) delivered within seven days. Eighty-four women had a positive Actim Partus test and 162 women a positive fFN test, of whom 54 (64%) and 63 (39%) delivered within seven days, respectively. Ninety-seven women had a cervical length below 15mm, of whom 50 (52%) delivered within seven days. Sensitivity, specificity, positive and negative predictive values of combining cervical length with the Actim Partus test or the fFN test were 91%, 75%, 47% and 97%, and 96%, 58%, 36% and 98%, respectively., Conclusion: According to this post-hoc study, in combination with cervical length, the Actim Partus test could be used as an alternative for the fFN test to identify women who will not deliver within seven days after presentation. Further evidence should be collected in a prospective comparative study., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Objective: To assess the impact of cervical length (CL) measurement and fetal fibronectin testing (fFN) on the clinicians' decision to prescribe antenatal corticosteroids (ACS) to women with symptoms of preterm labor., Study Design: This is a secondary analysis of a prospective cohort study including women with symptoms of preterm labor and intact membranes between 24 and 34 weeks' gestation. We compared the proportion prescribed and completed ACS courses, preterm delivery within seven days and median intervals from ACS to delivery in four groups: group 1 CL<10 mm, group 2 CL 10-30 mm and positive fFN, group 3 CL 10-30 mm and negative fFN, group 4 CL>30 mm., Results: ACS were prescribed to 63/65 (97%) women in group 1, 176/192 (91%) in group 2, 111/172 women (65%) in group 3 and 55/242 (23%) in group 4. In group 1, 42 (65%) women delivered within seven days, compared to 34 (18%) in group 2, 6 (3%) in group 3 and 3 (1%) in group 4. Median intervals between ACS and delivery were 6 days (IQR 3-61 days), 44 days (IQR 17-69 days), 53 days (IQR 37-77 days) and 66 days (IQR 43-78 days) in group 1, 2, 3 and 4 respectively., Conclusion: ACS were prescribed frequently to women with a CL of 10-30 mm and a negative fFN test or a CL>30 mm. There is room for improvement in the prescription of ACS in these low risk women., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Objective: To assess whether patient characteristics add to the fetal fibronectin test and cervical length measurement in the prediction of preterm delivery in symptomatic women., Study Design: A nationwide prospective cohort study was conducted in all ten perinatal centres in the Netherlands. Women with symptoms of preterm labour between 24 and 34 weeks gestation with intact membranes were invited. In all women qualitative fibronectin testing (0.050 μg/mL cut-off) and cervical length measurement were performed. Only singleton pregnancies were included in this analysis. Logistic regression was used to construct two multivariable models to predict spontaneously delivery within 7 days: a model including cervical length and fetal fibronectin as predictors, and an extended model including all potential predictors. The models were internally validated using bootstrapping techniques. Predictive performances were assessed as the area under the receiver operator characteristic curve (AUC) and calibration plots. We compared the models' capability to identify women with a low risk to deliver within 7 days. A risk less than 5%, corresponding to the risk for women with a cervical length of at least 25 mm, was considered as low risk., Results: Seventy-three of 600 included women (12%) had delivered spontaneously within 7 days. The extended model included maternal age, parity, previous preterm delivery, vaginal bleeding, C-reactive protein, cervical length, dilatation and fibronectin status. Both models had high discriminative performances (AUC of 0.92 (95% CI 0.88-0.95) and 0.95 (95% CI 0.92-0.97) respectively). Compared to the model with fibronectin and cervical length, our extended model reclassified 38 women (6%) from low risk to high risk and 21 women (4%) from high risk to low risk. Preterm delivery within 7 days occurred once in both the reclassification groups., Conclusion: In women with symptoms of preterm labour before 34 weeks gestation, a model that integrates maternal characteristics, clinical signs and laboratory tests, did not predict delivery within 7 days better than a model with only fibronectin and cervical length., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Objective: To stratify the risk of spontaneous preterm delivery using cervical length (CL) and fetal fibronectin (fFN) in women with threatened preterm labor who remained pregnant after 7 days., Design: Prospective observational study., Setting: Nationwide cohort of women with threatened preterm labor from the Netherlands., Population: Women with threatened preterm labor between 24 and 34 weeks with a valid CL and fFN measurement and remaining pregnant 7 days after admission., Methods: Kaplan-Meier and Cox proportional hazards models were used to estimate cumulative percentages and hazard ratios (HR) for spontaneous delivery., Main Outcome Measures: Spontaneous delivery between 7 and 14 days after initial presentation and spontaneous preterm delivery before 34 weeks., Results: The risk of delivery between 7 and 14 days was significantly increased for women with a CL < 15 mm or a CL ≥15 to <30 mm and a positive fFN, compared with women with a CL ≥30 mm: HR 22.3 [95% confidence interval (CI) 2.6-191] and 14 (95% CI 1.8-118), respectively. For spontaneous preterm delivery before 34 weeks the risk was increased for women with a CL < 15 mm [HR 6.3 (95% CI 2.6-15)] or with a CL ≥15 to <30 mm with either positive fFN [HR 3.6 (95% CI 1.5-8.7)] or negative fFN [HR 3.0 (95% CI 1.2-7.1)] compared with women with a CL ≥ 30 mm., Conclusions: In women remaining pregnant 7 days after threatened preterm labor, CL and fFN results can be used in risk stratification for spontaneous delivery., (© 2015 Nordic Federation of Societies of Obstetrics and Gynecology.)

Objective: To evaluate whether tocolysis with nifedipine can be omitted in women with symptoms of preterm labor, a shortened cervix, and negative fetal fibronectin test., Study Design: A randomized noninferiority trial was performed in all Dutch perinatal centers. Women with symptoms of preterm labor between 24 and 34 weeks, intact membranes, cervical length between 10 and 30 mm, and negative fibronectin test were randomly allocated to nifedipine (80 mg/day) or placebo. The primary outcome was delivery within 7 days. Secondary outcomes were severe neonatal morbidity and mortality. We also followed all eligible nonrandomized women., Results: We allocated 37 women to nifedipine and 36 women to placebo. In the nifedipine group, three women (8.1%) delivered within 7 days, compared with one woman (2.8%) in the placebo group (difference -5.3%; one-sided 95% confidence limit 4.5%). Median gestational age at delivery were respectively 37 + 0 (interquartile range [IQR] 34 + 6 to 38 + 5) and 38 + 2 (IQR 37 + 0 to 39 + 6) weeks (p = 0.008). In the nifedipine group, three pregnancies (8.1%) had a poor outcome; there were no poor outcomes in the placebo group. We observed similar trends in eligible nonrandomized women., Conclusion: In symptomatic women with preterm labor, a shortened cervix, and negative fibronectin test, placebo treatment is not inferior to tocolysis with nifedipine., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Objective: To estimate the performance of combining cervical length measurement with fetal fibronectin testing in predicting delivery in women with symptoms of preterm labor., Methods: We conducted a prospective nationwide cohort study in all 10 perinatal centers in The Netherlands. Women with symptoms of preterm labor between 24 and 34 weeks of gestation with intact membranes were included. In all women, qualitative fibronectin testing (0.050-microgram/mL cutoff) and cervical length measurement were performed. Logistic regression was used to predict spontaneous preterm delivery within 7 days after testing. A risk less than 5%, corresponding to the risk for women with a cervical length of at least 25 mm, was considered as low risk., Results: Between December 2009 and August 2012, 714 women were enrolled. Fibronectin results and cervical length were available for 665 women, of whom 80 (12%) delivered within 7 days. Women with a cervical length of at least 30 mm or with a cervical length between 15 and 30 mm with a negative fibronectin result were at low risk (less than 5%) of spontaneous delivery within 7 days. Fibronectin testing in case of a cervical length between 15 and 30 mm additionally classified 103 women (15% of the cohort) as low risk and 36 women (5% of the cohort) as high risk., Conclusion: Cervical length measurement, combined with fetal fibronectin testing in case of a cervical length between 15 and 30 mm, improves identification of women with a low risk to deliver spontaneously within 7 days., Level of Evidence: II.

Objective: The objective of the study was to evaluate the cost-effectiveness of risk stratification with cervical length (CL) measurement and/or fetal fibronectin (fFN) tests in women with threatened preterm labor between 24 and 34 weeks' gestation., Study Design: We performed a model-based cost-effectiveness analysis to evaluate 7 test-treatment strategies in women with threatened preterm labor from a health care system perspective. Estimates on disease prevalence, costs, and test accuracy were based on medical literature., Results: We found that additional fFN testing in the case of a CL between 10 and 30 mm is cost saving without compromising neonatal health outcomes, compared with a treat-all strategy or single CL testing. Implementing this strategy could lead to an annual cost saving between €2.8 million and €14.4 million in The Netherlands, a country with about 180,000 deliveries annually., Conclusion: In women with threatened preterm labor between 24 and 34 weeks of gestation, the most cost-effective test strategy uses a combination of CL and fFN testing., (Copyright © 2013 Mosby, Inc. All rights reserved.)