A multivariable model to guide the decision for pessary placement to prevent preterm birth in women with a multiple pregnancy: a secondary analysis of the ProTWIN trial

Cervical pessary to prevent preterm birth and poor neonatal outcome: An integrity meta-analysis of randomized controlled trials focusing on adherence to the European Medical Device Regulation

BACKGROUND

Findings from randomized trials (RCTs) on cervical pessary treatment to prevent spontaneous preterm birth are inconsistent.

OBJECTIVES

Our hypothesis suggests that adhering to the European Medical Device Regulation (MDR) and following the instructions for use are essential prerequisites for successful therapy. Conversely, the non-adherence to these guidelines will probably contribute to its failure.

SEARCH STRATEGY AND SELECTION CRITERIA

Based on validated criteria from integrity assessments we performed a systematic review identifying 14 RCTs evaluating the effect of cervical pessaries.

DATA COLLECTION AND ANALYSIS

We analyzed the implications of 14 criteria each accounting for 0-2 points of a score reflecting the clinical evaluation plan (CEP) as proposed by the MDR to evaluate the risk-benefit ratio of medical devices.

MAIN RESULTS

Seven RCTs in each singleton and twin pregnancies (5193 "cases") were included, detecting a high heterogeneity within control groups (I2 = 85% and 87%, respectively, P < 0.01). The CEP score varied from 11 to 26 points for all studies. The most common reasons for low scores and potential data compromise were poor recruitment rates, no (completed) power analysis, and no pre-registration, but mainly non-adherence to technical, biological, and clinical equivalence to the instructions for use as required by the MDR. All trials with score values greater than 20 had applied audit procedures. Within this group we found significantly reduced rates of spontaneous preterm birth at less than 34 weeks within the pessary group in singleton (odds ratio 0.28; 95% confidence interval 0.12-0.65) and twin pregnancies (odds ratio 0.30; 95% confidence interval 0.13-0.67). Similarly, there was a significant reduction in the composite poor neonatal outcome in singleton (odds ratio 0.25; 95% confidence interval 0.10-0.61) and twin pregnancies (odds ratio 0.54; 95% confidence interval 0.35-0.82) after a pessary as compared with controls.

CONCLUSION

Non-audited RCTs and meta-analyses mixing studies of different clinical quality as pre-defined by a CEP and the MDR pose the risk for erroneous conclusions.

Utility of cervical pessary in the prevention of preterm birth in triplet pregnancies: A single-center observational retrospective study of 165 triplet pregnancies

OBJECTIVE

Premature births are a health problem arising in triplet pregnancies, resulting in high levels of morbidity and mortality. The objective of this study is to evaluate the utility of cervical pessaries in reducing prematurity (<34 weeks) in triplet pregnancies.

METHODS

This is a single-center, retrospective case-control study regarding triplet pregnancies with follow-up at the La Paz University Hospital between 2000 and 2023. Maternal characteristics, obstetric and perinatal outcomes, and the use of cervical pessaries were examined.

RESULTS

165 triplet pregnancies were analyzed: 87 (52.7 %) in the case group (premature triplet pregnancies) and 78 in the control group (non-premature triplet pregnancies). A cervical pessary was inserted in 15 (17.2 %) triplet pregnancies in the case group and in 12 (16.7 %) triplet pregnancies in the control group (p = 0.92; OR = 1.04 (0.46-2.35)). A pessary was later inserted in the non-premature group (p = 0.01). The risk of preterm labor and the use of tocolytics ± glucocorticoids were found to be significantly more frequent in the premature group, with p = 0.01; OR = 2.30 (1.21-4.36) and p < 0.01; OR = 2.36 (1.23-4.44), respectively. Protocol-based cesarean sections were more frequent in the non-premature group (p < 0.01), while cesarean sections due to maternal complications (p < 0.01) and premature membrane rupture (p < 0.01) were more frequent in the premature group.

CONCLUSION

The cervical pessary is not useful in preventing preterm births (< 34 weeks) in triplet pregnancies. It is likely that being pregnant with triplets is a powerful independent factor associated with prematurity, despite other pregnancy conditions. Women who are pregnant with triplets and at risk of preterm labor and those taking tocolytics ± glucocorticoids may benefit from pessary insertion.

Cervical Pessary Plus Progesterone for Twin Pregnancy with Short Cervix Compared to Unselected and Non-Treated Twin Pregnancy: A Historical Equivalence Cohort Study (EPM Twin Pessary Study)

OBJECTIVE

 The present study aims to determine if the use of cervical pessary plus progesterone in short-cervix (≤ 25 mm) dichorionic-diamniotic (DC-DA) twin pregnancies is equivalent to the rate of preterm births (PBs) with no intervention in unselected DC-DA twin pregnancies.

METHODS

 A historical cohort study was performed between 2010 and 2018, including a total of 57 pregnant women with DC-DA twin pregnancies. The women admitted from 2010 to 2012 (n = 32) received no treatment, and were not selected by cervical length (Non-Treated group, NTG), whereas those admitted from 2013 to 2018 (n = 25), were routinely submitted to cervical pessary plus progesterone after the diagnosis of short cervix from the 18th to the 27th weeks of gestation (Pessary-Progesterone group, PPG). The primary outcome analyzed was the rate of PBs before 34 weeks.

RESULTS

 There were no statistical differences between the NTG and the PPG regarding PB < 34 weeks (18.8% versus 40.0% respectively; p = 0.07) and the mean birthweight of the smallest twin (2,037 ± 425 g versus 2,195 ± 665 g; p = 0.327). The Kaplan-Meyer Survival analysis was performed, and there were no differences between the groups before 31.5 weeks. Logistic regression showed that a previous PB (< 37 weeks) presented an odds ratio (OR) of 15.951 (95% confidence interval [95%CI]: 1.294-196.557; p = 0.031*) for PB < 34 weeks in the PPG.

CONCLUSION

 In DC-DA twin pregnancies with a short cervix, (which means a higher risk of PB), the treatment with cervical pessary plus progesterone could be considered equivalent in several aspects related to PB in the NTG, despite the big difference between these groups.

A randomized controlled trial on the use of pessary plus progesterone to prevent preterm birth in women with short cervical length (P5 trial)

BACKGROUND

Preterm birth is the leading cause of mortality and disability in newborn and infants. Having a short cervix increases the risk of preterm birth, which can be accessed by a transvaginal ultrasound scan during the second trimester. In women with a short cervix, vaginal progesterone and pessary can both reduce this risk, which progesterone more established than cervical pessary. The aim of this study is to compare the use of vaginal progesterone alone versus the association of progesterone plus pessary to prevent preterm birth in women with a short cervix.

METHODS

This is a pragmatic open-label randomized controlled trial that will take place in 17 health facilities in Brazil. Pregnant women will be screened for a short cervix with a transvaginal ultrasound between 18 0/7 until 22 6/7 weeks of gestational age. Women with a cervical length below or equal to 30 mm will be randomized to the combination of progesterone (200 mg) and pessary or progesterone (200 mg) alone until 36 + 0 weeks. The primary outcome will be a composite of neonatal adverse events, to be collected at 10 weeks after birth. The analysis will be by intention to treat. The sample size is 936 women, and a prespecified subgroup analysis is planned for cervical length (= < or > 25 mm). Categorical variables will be expressed as a percentage and continuous variables as mean with standard deviation. Time to delivery will be assessed with Kaplan-Meier analysis and Cox proportional hazard analysis.

DISCUSSION

In clinical practice, the combination of progesterone and pessary is common however, few studies have studied this association. The combination of treatment might act in both the biochemical and mechanical routes related to the onset of preterm birth.

TRIAL REGISTRATION

Brazilian Clinical Trial Registry (ReBec) RBR-3t8prz, UTN: U1111-1164-2636, 2014/11/18.

Midtrimester transvaginal ultrasound cervical length screening for spontaneous preterm birth in diamniotic twin pregnancies according to chorionicity

OBJECTIVE

To compare the mean transvaginal ultrasound (TVU) cervical length (CL) at midtrimester screening for spontaneous preterm birth in asymptomatic monochorionic diamniotic versus dichorionic diamniotic twin pregnancies STUDY DESIGN: This was a multicenter retrospective cohort study. Study subjects were identified at the time of a routine second trimester fetal ultrasound exam at 18 0/7-23 6/7 weeks gestation. We excluded women that received progesterone, pessary, or cerclage. Distribution of CL was determined and normality was examined. Mean of TVU CL were compared between monochorionic diamniotic and dichorionic diamniotic pregnancies. The relationship of TVU CL with gestational age (GA) at delivery and incidence of spontaneous preterm birth (SPTB) at different TVU CL cut offs were assessed. Incidence of short TVU CL, defined as TVU CL ≤30 mm, was also calculated in the two groups.

RESULTS

580 women with diamniotic twin pregnancies underwent TVU CL screening between 18 0/6 and 23 6/7 weeks. 175 (30.2%) were monochorionic diamniotic pregnancies, and 405 (69.8%) were dichorionic pregnancies. The demographic characteristics were similar on both groups. The mean GA at TVU CL was about 20 week in both groups. The mean TVU CL was significantly lower in the monochorionic diamniotic (32.8 ± 10.1) compared to the dichorionic (34.9 ± 8.6) group (MD -2.10 mm, 95% CI -3.91 to -0.29). TVU CL ≤30 mm was 16.6% (29/175) in the monochorionic group, and 11.9% (48/405) in the dichorionic group (aOR 1.48, 95% CI 1.03-2.43). Twins with a monochorionic diamniotic pregnancy had a significantly higher incidence of SPTB (53.1% vs 44.9%; aOR 1.22, 95% CI 1.22-1.79). For any given CL measured between 18 0-7 and 23 6/7 weeks, gestational age at delivery for monochorionic diamniotic pregnancies was about 2 weeks earlier compared to dichorionic pregnancies (MD -2.1 weeks; ANCOVA P < 0.001).

CONCLUSION

Monochorionic diamniotic twin pregnancies had a higher rate of spontaneous preterm birth than dichorionic diamniotic pregnancies. The higher rate of spontaneous preterm delivery in monochorionic pregnancies is associated with lower midtrimester TVU CL when compared to dichorionic pregnancies.

Development and evaluating multimarker models for guiding treatment decisions

Background

Despite the growing interest in developing markers for predicting treatment response and optimizing treatment decisions, an appropriate methodology to identify, combine and evaluate such markers has been slow to develop. We propose a step-by-step strategy for analysing data from existing randomised trials with the aim of identifying a multi-marker model for guiding decisions about treatment.

Methods

We start with formulating the treatment selection problem, continue with defining the treatment threshold, prepare a list of candidate markers, develop the model, apply the model to estimate individual treatment effects, and evaluate model performance in the study group of patients who meet the trial eligibility criteria. In this process, we rely on some well-known techniques for multivariable prediction modelling, but focus on predicting benefit from treatment, rather than outcome itself. We present our approach using data from a randomised trial in which 808 women with multiple pregnancy were assigned to cervical pessary or control, to prevent adverse perinatal outcomes. Overall, cervical pessary did not reduce the risk of adverse perinatal outcomes.

Results

The treatment threshold was zero. We had a preselected list of 5 potential markers and developed a logistic model including the markers, treatment and all marker-by-treatment interaction terms. The model was well calibrated and identified 35% (95% confidence interval (CI) 32 to 39%) of the trial participants as benefitting from pessary insertion. We estimated that the risk of adverse outcome could be reduced from 13.5 to 8.1% (5.4% risk reduction; 95% CI 2.1 to 8.6%) through model-based selective pessary insertion. The next step is external validation upon existence of independent trial data.

Conclusions

We suggest revisiting existing trials data to explore whether differences in treatment benefit can be explained by differences in baseline characteristics of patients. This could lead to treatment selection tools which, after validation in comparable existing trials, can be introduced into clinical practice for guiding treatment decisions in future patients.

Controversies about the Secondary Prevention of Spontaneous Preterm Birth

Preterm birth is one of the major global health problems and part of the Millennium Development goals because of the associated high number of perinatal or neonatal mortality and long-term risks of neurodevelopmental and metabolic diseases. Transvaginal sonography has meanwhile been established as a screening tool for spontaneous preterm birth despite its relatively low sensitivity when considering only the cervical length. Vaginal progesterone has been shown to reduce prematurity rates below 34 weeks in a screening population of singleton pregnancies. Up to now, no positive long-term effect could be demonstrated after 2 years. It seems to have no benefit to prolong pregnancies after a period of preterm contractions and in risk patients without cervical shortening. Meta-analyses still demonstrate conflicting results dependent on quality criteria used for selection. A cerclage is only indicated in singleton pregnancies with previous spontaneous preterm birth and a combined cervical shortening in the current pregnancy. Nevertheless, the short- and long-term outcome has never been evaluated, whereas maternal complications may be increased. There is no evidence for a prophylactic cervical cerclage in twin pregnancies even in cases with cervical shortening. Emergency cerclage remains an indication after individual counseling. The effect of a cervical pessary in singleton pregnancy seems to be more pronounced in studies where a few investigators with increasing experience have treated and followed the patients at risk for preterm birth. Mainly in twin pregnancies, pessary treatment seems to be promising compared to other treatment options of secondary prevention when the therapy is started at early stages of precocious cervical ripening. At present, several international trials with the goal to reduce global rates of prematurity are in progress which will hopefully allow to specify the indications and methods of intervention for certain subgroups. When trials are summarized, prospective meta-analyses carry a lower risk of bias than the meanwhile uncontrolled magnitude of retrospective meta-analyses with conflicting results.

Pessary for prevention of preterm birth in twin pregnancy with short cervix: 3-year follow-up study

OBJECTIVE

A recent randomized clinical trial (ProTWIN) showed that a cervical pessary prevented preterm birth and improved neonatal outcome in women with multiple pregnancy and cervical length (CL) < 38 mm. In this follow-up study, the long-term developmental outcome of these children was evaluated at 3 years' corrected age.

METHODS

This was a follow-up study of ProTWIN, a multicenter trial conducted between 2009 and 2012 in which asymptomatic women with a multiple pregnancy were randomized to placement of a cervical pessary or no intervention. Current follow-up and analysis were limited to mothers with a mid-trimester CL < 38 mm (78 women (157 children) in the pessary group and 55 women (111 children) in the control group). At 3 years of corrected age, surviving children were invited for a Bayley Scales of Infant and Toddler Development-third edition (Bayley-III) assessment. Death after randomization or neurodevelopmental disability (Bayley-III score of ≤ 85, 1 SD below mean) rates were compared between the pessary and control groups, according to the intention-to-treat principle and using multiple imputation for missing data. Mean Bayley-III scores in surviving children were also assessed. A linear mixed-effects model was used to adjust for correlation between children of one mother.

RESULTS

From the time of entry in the ProTWIN trial until follow-up at 3 years of age, a total of 27 children had died (six (5%) in the pessary vs 21 (26%) in the control group; odds ratio (OR), 0.13; 95% CI, 0.04-0.48). Bayley-III outcomes were collected for 173/241 (72%) surviving children (114 (75%) in the pessary vs 59 (66%) in the control group). The cumulative incidence of death or survival with a neurodevelopmental disability was 12 (10%) in the pessary vs 23 (29%) in the control group (OR, 0.26; 95% CI, 0.09-0.73). No statistical or clinically relevant differences were found with respect to cognitive, language and motor development among surviving children between the groups. Comparable results were found after multiple imputation.

CONCLUSION

In women with twin pregnancy and a CL < 38 mm, the use of a cervical pessary strongly improved survival of the children without affecting neurodevelopment at 3 years' corrected age. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.