The Biomarkers for Preterm Birth Study-A prospective observational study comparing the impact of vaginal biomarkers on clinical practice when used in women with symptoms of preterm labor

Quantitative cervicovaginal fluid fetal fibronectin: A liquid biopsy for intra-amniotic inflammation

INTRODUCTION

Intra-amniotic inflammation is causally linked to spontaneous preterm labor. The gold standard for the diagnosis of intra-amniotic inflammation is the determination of an amniotic fluid profile obtained from transabdominal amniocentesis, which is invasive. Cervicovaginal fluid fetal fibronectin (fFN) is a widely-used predictive biomarker for spontaneous preterm labor. The aims of this study are to determine (1) whether a quantitative cervicovaginal fluid fFN test can be used to identify the presence of intra-amniotic inflammation; and (2) an appropriate cut-off value of a cervicovaginal fluid fFN concentration for the identification of intra-amniotic inflammation.

MATERIAL AND METHODS

This prospective cohort study included 78 patients with preterm labor and intact membranes who had a sample collected for quantitative cervicovaginal fluid fFN measurement and underwent transabdominal amniocentesis. Intra-amniotic inflammation was defined as an amniotic fluid interleukin-6 concentration ≥2.6 ng/mL. Clinicians were masked from the results of cervicovaginal fluid fFN and amniotic fluid interleukin-6 concentrations. Logistic regression analysis was used to determine which factors were significant predictors of intra-amniotic inflammation. The diagnostic indices of the cervicovaginal fluid fFN test for the identification of intra-amniotic inflammation were calculated.

RESULTS

(1) Frequency of intra-amniotic inflammation was 26.9% (21/78); (2) the higher the cervicovaginal fluid fFN concentration, the greater the risk of intra-amniotic inflammation (p < 0.001); (3) cervicovaginal fluid fFN concentration ≥125 ng/mL had an area under the curve of 0.91 (95% confidence interval: 0.83-0.96) for the identification of intra-amniotic inflammation with 100% sensitivity, 100% negative predictive value, 82.46% specificity and a positive likelihood ratio of 5.7; and (4) cervicovaginal fluid fFN cut-off of 125 ng/mL had a significant higher predictive performance than the traditional cut-off (50 ng/mL) for the identification of intra-amniotic inflammation.

CONCLUSIONS

Quantitative cervicovaginal fluid fFN with a cut-off of 125 ng/mL had a high sensitivity and a negative predictive value as well as a positive likelihood ratio for the identification of intra-amniotic inflammation. Its high sensitivity and negative predictive value can be used to decrease an index of suspicion of intra-amniotic inflammation. This test may be useful as an initial assessment test to select appropriate patients for amniocentesis to determine intra-amniotic inflammation.

Outperformance of interleukin-6 over placental alpha microglobulin-1 in predicting preterm delivery in symptomatic women

BACKGROUND

Threatened preterm labor is the major cause of hospital admission during the second half of pregnancy. An early diagnosis is crucial for adopting pharmacologic measures to reduce perinatal mortality and morbidity. Current diagnostic criteria are based on symptoms and short cervical length. However, there is a high false-positive rate when using these criteria, which implies overtreatment, causing unnecessary side effects and an avoidable economic burden.

OBJECTIVE

This study aimed to compare the use of placental alpha microglobulin-1 and interleukin-6 as vaginal biomarkers combined with cervical length and other maternal characteristics to improve the prediction of preterm delivery in symptomatic women.

STUDY DESIGN

A prospective observational study was conducted in women with singleton pregnancies complicated by threatened preterm labor with intact membranes at 24+0 to 34+6 weeks of gestation. A total of 136 women were included in this study. Vaginal fluid was collected with a swab for placental alpha microglobulin-1 determination using the PartoSure test, interleukin-6 was assessed by electrochemiluminescence immunoassay, cervical length was measured by transvaginal ultrasound, and obstetrical variables and newborn details were retrieved from clinical records. These characteristics were used to fit univariate binary logistic regression models to predict time to delivery <7 days, time to delivery <14 days, gestational age at delivery ≤34 weeks, and gestational age at delivery ≤37 weeks, and multivariate binary logistic regression models were fitted with imbalanced and balanced data. Performance of models was assessed by their F2-scores and other metrics, and the association of their variables with a risk or a protective factor was studied.

RESULTS

A total of 136 women were recruited, of whom 8 were lost to follow-up and 7 were excluded. Of the remaining 121 patients, 22 had a time to delivery <7 days and 31 had a time to delivery <14 days, and 30 deliveries occurred with a gestational age at delivery ≤34 weeks and 55 with a gestational age at delivery ≤37 weeks. Univariate binary logistic regression models fitted with the log transformation of interleukin-6 showed the greatest F2-scores in most studies, which outperformed those of models fitted with placental alpha microglobulin-1 (log[interleukin-6] vs placental alpha microglobulin-1 in time to delivery <7 days: 0.38 vs 0.30; time to delivery <14 days: 0.58 vs 0.29; gestational age at delivery ≤34 weeks: 0.56 vs 0.29; gestational age at delivery ≤37 weeks: 0.61 vs 0.16). Multivariate logistic regression models fitted with imbalanced data sets outperformed most univariate models (F2-score in time to delivery <7 days: 0.63; time to delivery <14 days: 0.54; gestational age at delivery ≤34 weeks: 0.62; gestational age at delivery ≤37 weeks: 0.73). The performance of prediction of multivariate models was drastically improved when data sets were balanced, and was maximum for time to delivery <7 days (F2-score: 0.88±0.2; positive predictive value: 0.86±0.02; negative predictive value: 0.89±0.03).

CONCLUSION

A multivariate assessment including interleukin-6 may lead to more targeted treatment, thus reducing unnecessary hospitalization and avoiding unnecessary maternal-fetal treatment.

Prediction of spontaneous preterm birth using CCL2 and CXCL10 in maternal serum of symptomatic high-risk pregnant women: a prospective cohort study

INTRODUCTION

CCL2 and CXCL10 are putative biomarkers for the prediction of spontaneous preterm birth. This study evaluates these markers in a cohort of pregnant high-risk women.

MATERIAL AND METHODS

In our prospective study, we included 109 women with signs of preterm labor between 20 + 0 and 31 + 6 weeks of gestation. Inclusion criteria were regular (< 3/30 min) or painful contractions, cervical length < 25 mm or a history of previous preterm birth (PTB). Blood samples were obtained upon first admission to our clinic. Biomarker concentrations were measured using pre-coated sandwich immunoassays (ELISA). Primary study outcome was spontaneous preterm birth < 34 weeks, secondary outcome was delivery < 37 weeks or within seven days after study inclusion.

RESULTS

Sixteen women (14.7%) delivered < 34 weeks and twenty women between 34 + 0 and 36 + 6 weeks (18.4%). Six patients (5.5%) gave birth within seven days after study admission. CXCL10 showed higher medium serum levels in women with PTB < 34 weeks (115 pg/ml compared to 61 pg/ml ≥ 34 weeks; p < 0.001) and < 37 weeks (103 pg/ml vs. 53 pg/ml; p < 0.001). In contrary, lower CCL2 serum levels were associated with PTB < 34 weeks (46 pg/ml vs. 73 pg/ml; p = 0.032) and birth within 7 days (25 pg/ml vs. 73 pg/ml; p = 0.008). The CXCL10/CCL2-ratio further improved the predictive model with a ROC-AUC of 0.83 (95% CI 0.73-0.93, p < 0.001) for delivery < 34 weeks. These corresponds to a sensitivity, specificity and positive predictive value of 0.67, 0.86 and 0.43 at a cut-off of 2.2.

CONCLUSION

Low maternal serum CCL2 levels are associated with a higher risk of preterm delivery within seven days. High CXCL10 serum levels are more associated with a high risk for preterm birth < 34 weeks. Elevated CXCL10/CCL2-ratio is showing the best predictive performance.

TRIAL REGISTRATION NUMBER (DRKS-ID)

DRKS00010763, Registration date: September 02, 2016.

Preterm labor with intact membranes: a simple noninvasive method to identify patients at risk for intra-amniotic infection and/or inflammation

OBJECTIVE

To develop a noninvasive scoring system to identify patients at high risk for intra-amniotic infection and/or inflammation, which would reduce the need for amniocentesis.

METHODS

This prospective cohort study comprised patients admitted with preterm labor and intact membranes (20-34 weeks of gestation) who underwent a transabdominal amniocentesis and for whom concentrations of quantitative cervical fetal fibronectin and of maternal serum C-reactive protein (CRP) were determined. Intra-amniotic infection was defined as a positive amniotic fluid culture for microorganisms. Intra-amniotic inflammation was defined as an amniotic fluid matrix metalloproteinase-8 concentration >23 ng/mL. Multivariate logistic regression analysis was performed to identify intra-amniotic infection/inflammtion with noninvasive parameters that had a significant relationship with univariate analysis. With four parameters identified by multivariate analysis, we generated a noninvasive risk scoring system.

RESULTS

Of the study population consisting of 138 singleton pregnant women, (1) the overall rate of intra-amniotic infection/inflammation was 28.3% (39/138); (2) four parameters were used to develop a noninvasive risk scoring system [i.e. cervical fetal fibronectin concentration (score 0-2), maternal serum CRP concentration (score 0-2), cervical dilatation (score 0-2), and gestational age at presentation (score 0-1)]; the total score ranges from 0 to 7; 3) the area under the curve of the risk score was 0.96 (95% confidence interval (CI), 0.92-0.99), significantly higher than that of each predictor in the identification of intra-amniotic infection/inflammation (p < .001, for all); 4) the risk score with a cutoff of 4 had a sensitivity of 94.9% (37/39), a specificity of 90.9% (90/99), a positive predictive value of 80.4% (37/46), a negative predictive value of 97.8% (90/92), a positive likelihood ratio of 10.4 (95% CI, 5.6-19.5), and a negative likelihood ratio of 0.06 (95% CI, 0.15-0.22) in the identification of intra-amniotic infection/inflammation.

CONCLUSIONS

(1) The combination of four parameters (concentrations of cervical fetal fibronectin and maternal serum CRP, cervical dilatation, and gestational age) was independently associated with intra-amniotic infection and/or inflammation; and (2) the risk scoring system comprised of the combination of 4 noninvasive parameters was sensitive and specific to identify the patients at risk for intra-amniotic infection and/or inflammation.

The use of PAMG-1 testing in patients with preterm labor, intact membranes and a short sonographic cervix reduces the rate of unnecessary antenatal glucocorticoid administration

OBJECTIVES

To assess the frequency of antenatal corticosteroid (ACS) administration in cases with shortened cervical length by addition of placental alpha-microglobulin-1 (PAMG-1) testing to sonographic examination.

METHODS

Single centre retrospective cohort study. Rate of ACS administration was compared between cases with cervical length between 15 and 25 mm and cases with positive PAMG-1 testing and cervical length between 15 and 25 mm. We evaluated the following outcome parameters: Rate of ACS administration, gestational age at delivery, time to delivery, delivery within seven days, delivery <34 and <37 weeks' gestation, rate of admission to neonatal intensive care unit (NICU).

RESULTS

In total, 130 cases were included. "PAMG-1 group" consisted of 68 women, 62 cases built the "historical control group". ACS administration was performed less frequently in the "PAMG-1 cohort" (18 (26%) vs. 46 (74%); p<0.001). The rate of delivery within seven days did not differ (2 (3%) vs. 4 (6.5%); p=0.4239). The rates of delivery <34 weeks' gestation (7 (10%) vs. 9 (15%); p=0.4643) and <37 weeks' gestation (19 (28%) vs. 26 (42%); p=0.0939) did not differ. Time to delivery interval was longer in the PAMG-1 group (61.5 vs. 43 days, p=0.0117). NICU admission occurred more often in the "historical control group" (22 (38%) vs. 28 (60%); p=0.0272).

CONCLUSIONS

Addition of biomarker testing can help to avoid unnecessary ACS administrations in women with shortened cervical length.

Prediction of Spontaneous Preterm Birth in At-risk Women Using Thrombospondin 1 from Cervicovaginal Fluid: A Prospective Observational Study

Introduction Thrombospondin 1, desmoplakin and stratifin are putative biomarkers for the prediction of preterm birth. This study aimed to validate the predictive capability of these biomarkers in patients at risk of preterm birth.

Materials and Methods We included 109 women with symptoms of threatened spontaneous preterm birth between weeks 20 0/7 and 31 6/7 of gestation. Inclusion criteria were uterine contractions, cervical length of less than 25 mm, or a personal history of spontaneous preterm birth. Multiple gestations were also included. Samples of cervicovaginal fluid were taken before performing a digital examination and transvaginal ultrasound. Levels of cervicovaginal thrombospondin 1, desmoplakin and stratifin were quantified by enzyme-linked immunosorbent assays. The primary endpoint was spontaneous preterm birth before 34 + 0 weeks of gestation.

Results Sixteen women (14.7%) delivered before 34 + 0 weeks. Median levels of thrombospondin 1 were higher in samples where birth occurred before 34 weeks vs. ≥ 34 weeks of gestation (4904 vs. 469 pg/mL, p < 0.001). Receiver operator characteristics analysis resulted in an area under the curve of 0.86 (p < 0.0001). At an optimal cut-off value of 2163 pg/mL, sensitivity, specificity, positive predictive value and negative predictive value were 0.94, 0.77, 0.42 and 0.99, respectively, with an adjusted odds ratio of 32.9 (95% CI: 3.1 – 345, p = 0.004). Multiple gestation, cervical length, and preterm labor had no impact on the results. Survival analysis revealed a predictive period of more than eight weeks. Levels of desmoplakin and stratifin did not differ between groups.

Conclusion Thrombospondin 1 allowed long-term risk estimation of spontaneous preterm birth.

Using quantitative fetal fibronectin to predict term labour onset in Australian rural women: A pilot study

BACKGROUND

Many women living in rural and remote Australia are required to travel large distances to birth in a hospital with maternity facilities, incurring considerable financial, social and emotional burden for them and their families. No studies to date have investigated the use of quantitative fetal fibronectin (qfFN) to predict term labour in asymptomatic pregnant women. A tool which is able to more accurately predict term labour has the potential to guide informed travel decision-making for women and healthcare professionals in rural and remote Australia.

AIM

The aim of this study is to determine if qfFN can reliably predict term labour in asymptomatic women from rural and remote areas.

MATERIALS AND METHODS

Thirty-nine women from rural Australia provided 71 fFN samples between June 2016 and October 2018, from 37 weeks' gestation, with at least one week between samples for those providing multiple samples. Days from fFN sampling until spontaneous onset of labour were recorded. Using generalised estimating equation modelling we examined the utility of fFN as a predictor for onset of labour at term after adjusting for confounders.

RESULTS

There was a small-to-moderate negative correlation (r_s -0.27, P < 0.05) between time until labour and fFN. Quantitative fFN was observed to be a significant predictor of time until labour after adjusting for confounding variables (P < 0.001).

CONCLUSION

fFN levels may play a role in predicting term labour in rural women; however, future studies with a larger sample size are required to validate the findings of our pilot study.

Diagnostic accuracy of quantitative fetal fibronectin to predict spontaneous preterm birth: A meta-analysis

BACKGROUND

Use of quantitative fetal fibronectin (fFN) testing to predict spontaneous preterm birth (sPTB) is gaining attention owing to its absolute measurement of fFN concentration and increased positive predictive value compared with qualitative testing.

OBJECTIVE

To assess the predictive values of quantitative fFN for sPTB in different predefined thresholds using systematic review and meta-analysis.

SEARCH STRATEGY

Five major databases (PubMed, ScienceDirect, Web of Science, Embase, Cochrane library) were searched for eligible studies.

SELECTION CRITERIA

Observational studies of the diagnostic accuracy of different quantitative fFN thresholds on delivery outcomes were included.

DATA COLLECTION AND EXTRACTION

Articles were reviewed independently by two authors and data were extracted. Sensitivity, specificity, diagnostic odds ratio, and summary receiver operating characteristic curves were extracted and calculated.

MAIN RESULTS

Fifteen studies were included. To detect sPTB at less than 34 weeks of gestation, pooled sensitivities for thresholds of 10, 50, 200, and 500 ng/ml were 0.78, 0.56, 0.33, and 0.11, respectively. Pooled specificities were 0.63, 0.84, 0.96, and 0.99, respectively.

CONCLUSIONS

Based on the results of the meta-analysis, the threshold of 10 ng/ml fFN may be a new choice for the prediction of sPTB. The improved diagnostic accuracy of quantitative testing over qualitative testing can provide additional discriminatory information for clinical practice.