Completeness of Retention Data and Determinants of Attrition in Birth Cohorts of Very Preterm Infants: A Systematic Review

Tocolysis after preterm prelabor rupture of membranes and 5-year outcomes: a population-based cohort study

BACKGROUND

The administration of tocolytics after preterm prelabor rupture of membranes remains a controversial practice. In theory, reducing uterine contractility should delay delivery and allow for optimal antenatal management, thereby reducing the risks for prematurity and adverse consequences over the life course. However, tocolysis may be associated with neonatal death or long-term adverse neurodevelopmental outcomes, mainly related to prolonged fetal exposure to intrauterine infection or inflammation. In a previous study, we showed that tocolysis administration was not associated with short-term benefits. There are currently no data available to evaluate the impact of tocolysis on neurodevelopmental outcomes in school-aged children born prematurely in this clinical setting.

OBJECTIVE

This study aimed to investigate whether tocolysis administered after preterm prelabor rupture of membranes is associated with neurodevelopmental outcomes at 5.5 years of age.

STUDY DESIGN

We used data from a prospective, population-based cohort study of preterm births recruited in 2011 (referred to as the EPIPAGE-2 study) and for whom the results of a comprehensive medical and neurodevelopmental assessment of the infant at age 5.5 years were available. We included pregnant individuals with preterm prelabor rupture of membranes at 24 to 32 weeks' gestation in singleton pregnancies with a live fetus at the time of rupture, birth at 24 to 34 weeks' gestation, and participation of the infant in an assessment at 5.5 years of age. Exposure was the administration of any tocolytic treatment after preterm prelabor rupture of membranes. The main outcome was survival without moderate to severe neurodevelopmental disabilities at 5.5 years of age. Secondary outcomes included survival without any neurodevelopmental disabilities, cerebral palsy, full-scale intelligence quotient, developmental coordination disorders, and behavioral difficulties. A propensity-score analysis was used to minimize the indication bias in the estimation of the treatment effect on outcomes.

RESULTS

Overall, 596 of 803 pregnant individuals (73.4%) received tocolytics after preterm prelabor rupture of membranes. At the 5.5-year follow-up, 82.7% and 82.5% of the children in the tocolysis and no tocolysis groups, respectively, were alive without moderate to severe neurodevelopmental disabilities; 52.7% and 51.1%, respectively, were alive without any neurodevelopmental disabilities. After applying multiple imputations and inverse probability of treatment weighting, we found no association between the exposure to tocolytics and survival without moderate to severe neurodevelopmental disabilities (odds ratio, 0.93; 95% confidence interval, 0.55-1.60), survival without any neurodevelopmental disabilities (odds ratio, 1.02; 95% confidence interval, 0.65-1.61), or any of the other outcomes.

CONCLUSION

There was no difference in the neurodevelopmental outcomes at age 5.5 years among children with and without antenatal exposure to tocolysis after preterm prelabor rupture of membranes. To date, the health benefits of tocolytics remain unproven, both in the short- and long-term.

Comparing behavioural outcomes in children born extremely preterm between 2006 and 1995: the EPICure studies

BACKGROUND

Children born extremely preterm (EP) are at increased risk of neurocognitive and behavioural morbidity. Here, we investigate whether behavioural outcomes have changed over time concomitant with increasing survival following EP birth.

METHODS

Comparison of outcomes at 11 years of age for two prospective national cohorts of children born EP in 1995 (EPICure) and 2006 (EPICure2), assessed alongside term-born children. Behavioural outcomes were assessed using the parent-completed Strengths and Difficulties Questionnaire (SDQ), DuPaul Attention-Deficit/Hyperactivity Disorder Rating Scale (ADHD-RS), and Social Communication Questionnaire (SCQ).

RESULTS

In EPICure, 176 EP and 153 term-born children were assessed (mean age: 10.9 years); in EPICure2, 112 EP and 143 term-born children were assessed (mean age: 11.8 years). In both cohorts, EP children had higher mean scores and more clinically significant difficulties than term-born children on almost all measures. Comparing outcomes for EP children in the two cohorts, there were no significant differences in mean scores or in the proportion of children with clinically significant difficulties after adjustment for confounders. Using term-born children as reference, EP children in EPICure2 had significantly higher SDQ total difficulties and ADHD-RS hyperactivity impulsivity z-scores than EP children in EPICure.

CONCLUSIONS

Behavioural outcomes have not improved for EP children born in 2006 compared with those born in 1995. Relative to term-born peers, EP children born in 2006 had worse outcomes than those born in 1995. There is an ongoing need for long-term clinical follow-up and psychological support for children born EP.

Using Digital Tools to Study the Health of Adults Born Preterm at a Large Scale: e-Cohort Pilot Study

BACKGROUND

Preterm birth is a global health concern. Its adverse consequences may persist throughout the life course, exerting a potentially heavy burden on families, health systems, and societies. In high-income countries, the first children who benefited from improved care are now adults entering middle age. However, there is a clear gap in the knowledge regarding the long-term outcomes of individuals born preterm.

OBJECTIVE

This study aimed to assess the feasibility of recruiting and following up an e-cohort of adults born preterm worldwide and provide estimations of participation, characteristics of participants, the acceptability of questions, and the quality of data collected.

METHODS

We implemented a prospective, open, observational, and international e-cohort pilot study (Health of Adult People Born Preterm-an e-Cohort Pilot Study [HAPP-e]). Inclusion criteria were being an adult (aged ≥18 years), born preterm (<37 weeks of gestation), having internet access and an email address, and understanding at least 1 of the available languages. A large, multifaceted, and multilingual communication strategy was established. Between December 2019 and June 2021, inclusion and repeated data collection were performed using a secured web platform. We provided descriptive statistics regarding participation in the e-cohort, namely, the number of persons who registered on the platform, signed the consent form, initiated and completed the baseline questionnaire, and initiated and completed the follow-up questionnaire. We also described the main characteristics of the HAPP-e participants and provided an assessment of the quality of the data and the acceptability of sensitive questions.

RESULTS

As of December 31, 2020, a total of 1004 persons had registered on the platform, leading to 527 accounts with a confirmed email and 333 signed consent forms. A total of 333 participants initiated the baseline questionnaire. All participants were invited to follow-up, and 35.7% (119/333) consented to participate, of whom 97.5% (116/119) initiated the follow-up questionnaire. Completion rates were very high both at baseline (296/333, 88.9%) and at follow-up (112/116, 96.6%). This sample of adults born preterm in 34 countries covered a wide range of sociodemographic and health characteristics. The gestational age at birth ranged from 23+6 to 36+6 weeks (median 32, IQR 29-35 weeks). Only 2.1% (7/333) of the participants had previously participated in a cohort of individuals born preterm. Women (252/333, 75.7%) and highly educated participants (235/327, 71.9%) were also overrepresented. Good quality data were collected thanks to validation controls implemented on the web platform. The acceptability of potentially sensitive questions was excellent, as very few participants chose the "I prefer not to say" option when available.

CONCLUSIONS

Although we identified room for improvement in specific procedures, this pilot study confirmed the great potential for recruiting a large and diverse sample of adults born preterm worldwide, thereby advancing research on adults born preterm.

Heterogeneity of design features in studies included in systematic reviews with meta-analysis of cognitive outcomes in children born very preterm

BACKGROUND

Meta-analyses of the voluminous scientific literature on the impact of very preterm (VPT, <32 weeks' gestation) birth on cognition find a marked deficit in intelligence quotient (IQ) among children born VPT relative to term-born peers, but with unexplained between-study heterogeneity in effect size.

OBJECTIVES

To conduct an umbrella review to describe the design and methodology of primary studies and to assess whether methodological heterogeneity affects the results of meta-analyses.

DATA SOURCES

Primary studies from five systematic reviews with meta-analysis on VPT birth and childhood IQ.

STUDY SELECTION AND DATA EXTRACTION

Information on study design, sample characteristics and results was extracted from studies. Study features covered study type, sample size, follow-up rates, adjustment for social context, management of severe impairments and test type.

SYNTHESIS

We used random-effects subgroup meta-analyses and meta-regressions to investigate the contribution of study features to between-study variance in standardised mean differences (SMD) in IQ between groups.

RESULTS

In 58 cohorts (56%), children with severe impairments were excluded, while 23 (22%) cohorts accounted for social factors. The least reported feature was the follow-up rate (missing in 38 cohorts). The largest difference in SMDs was between studies using full scale IQ tests (61 cohorts, SMD -0.89, 95% CI -0.96, -0.82) versus short-form tests (27 cohorts, SMD -0.68, 95% CI -0.79, -0.57). The proportion of between-study variance explained by the type of test was 14%; the other features explained less than 1% of the variance.

CONCLUSIONS

Study design and methodology varied across studies, but most of them did not affect the variance in effect size, except the type of cognitive test. Key features, such as the follow-up rate, were not consistently reported limiting the evaluation of their potential contribution. Incomplete reporting limited the evaluation of the full impact of this methodological diversity.

Factors related to retention in a longitudinal study of infants at familial risk for autism

Background

Reporting retention data is critical to determining the soundness of a study's conclusions (internal validity) and broader generalizability (external validity). Although selective attrition can lead to overestimates of effects, biased conclusions, or overly expansive generalizations, retention rates are not reported in many longitudinal studies.

Methods

We examined multiple child- and family-level factors potentially associated with retention in a longitudinal study of younger siblings of children with autism spectrum disorder (ASD; n = 304) or typical development (n = 163). The sample was followed from the first year of life to 36 months of age, for up to 7 visits.

Results

Of the 467 infant siblings who were consented and participated in at least one research visit, 397 (85.0%) were retained to study completion at 36 months. Retention rates did not differ by familial risk group (ASD-risk vs. Low-risk), sex, race, ethnicity, age at enrollment, number of children in the family, maternal employment, marital status, or parent concerns about the child at enrollment. A stepwise regression model identified 4 variables that, together, provided the most parsimonious predictive model of study retention: maternal education, maternal age at child's birth, travel distance to the study site, and diagnostic outcome classification at the final study visit.

Conclusions

The retained and not-retained groups did not differ on most demographic and clinical variables, suggesting few threats to internal and external validity. The significantly higher rate of retention of children diagnosed with ASD (95%) than typically developing children (83%) may, however, present biases when studying recurrence risk. We conclude by describing engagement and tracking methods that can be used to maximize retention in longitudinal studies of children at risk of ASD.

Survey of data collection methods and retention strategies in European birth cohorts of children and adults born very preterm

BACKGROUND

The long-term follow-up of very preterm and very low birthweight cohorts contributes to valuable evidence to understand life-course outcomes in these vulnerable populations. However, attrition is a major challenge in long-term outcome studies. Examining the techniques used by existing cohorts may help to reveal practices that enhance willingness to continue participation over time.

OBJECTIVES

To evaluate the effect of data collection methods and retention strategies on overall retention in European birth cohorts of individuals born very preterm and very low birthweight.

METHODS

A survey of European cohorts integrated in the RECAP-preterm Consortium provided data on study characteristics, retention at the most recent follow-up, data collection methods and retention strategies. Cohorts were classified according to participants' age at most recent follow-up as child (<18) or adult cohorts (≥18 years old).

RESULTS

Data were obtained for 17 (81%) cohorts (7 adult and 10 child) in 12 countries. Considering the baseline, at the most recent follow-up, overall retention ranged from 10% to 99%. Child cohorts presented higher median retention (68% versus 38% or 52% for adult cohorts with ≤5 or >5 follow-ups) and used relatively more retention strategies. For contact and invitation, cohorts mostly resorted to invitation letters, and to face-to-face interviews for assessments. Study duration was negatively correlated with retention and positively associated with the number of follow-up evaluation. We identified 109 retention strategies, with a median of 6 per cohort; bond-building (n = 41; 38%) was the most utilised, followed by barrier-reduction (n = 36; 33%) and reminders (n = 32; 29%). Retention was not influenced by category or number of strategies.

CONCLUSIONS

Regular contact with cohort participants favour retention whilst neither the number nor the categories of retention strategies used seemed to have an influence, suggesting that tailored strategies focussed on participants at higher risk of dropout might be a more effective approach.

Machine learning methods to predict attrition in a population-based cohort of very preterm infants

The timely identification of cohort participants at higher risk for attrition is important to earlier interventions and efficient use of research resources. Machine learning may have advantages over the conventional approaches to improve discrimination by analysing complex interactions among predictors. We developed predictive models of attrition applying a conventional regression model and different machine learning methods. A total of 542 very preterm (< 32 gestational weeks) infants born in Portugal as part of the European Effective Perinatal Intensive Care in Europe (EPICE) cohort were included. We tested a model with a fixed number of predictors (Baseline) and a second with a dynamic number of variables added from each follow-up (Incremental). Eight classification methods were applied: AdaBoost, Artificial Neural Networks, Functional Trees, J48, J48Consolidated, K-Nearest Neighbours, Random Forest and Logistic Regression. Performance was compared using AUC- PR (Area Under the Curve—Precision Recall), Accuracy, Sensitivity and F-measure. Attrition at the four follow-ups were, respectively: 16%, 25%, 13% and 17%. Both models demonstrated good predictive performance, AUC-PR ranging between 69 and 94.1 in Baseline and from 72.5 to 97.1 in Incremental model. Of the whole set of methods, Random Forest presented the best performance at all follow-ups [AUC-PR₁: 94.1 (2.0); AUC-PR₂: 91.2 (1.2); AUC-PR₃: 97.1 (1.0); AUC-PR₄: 96.5 (1.7)]. Logistic Regression performed well below Random Forest. The top-ranked predictors were common for both models in all follow-ups: birthweight, gestational age, maternal age, and length of hospital stay. Random Forest presented the highest capacity for prediction and provided interpretable predictors. Researchers involved in cohorts can benefit from our robust models to prepare for and prevent loss to follow-up by directing efforts toward individuals at higher risk.

OUP accepted manuscript

Very preterm children are more likely to exhibit difficulties in socio-emotional processing than their term-born peers. Emerging socio-emotional problems may be partly due to alterations in limbic system development associated with infants’ early transition to extrauterine life. The amygdala is a key structure in this system and plays a critical role in various aspects of socio-emotional development, including emotion regulation. The current study tested the hypothesis that amygdala resting-state functional connectivity at term-equivalent age would be associated with socio-emotional outcomes in childhood. Participants were 129 very preterm infants (<33 weeks' gestation) who underwent resting-state functional MRI at term and received a neurodevelopmental assessment at 4–7 years (median = 4.64). Using the left and right amygdalae as seed regions, we investigated associations between whole-brain seed-based functional connectivity and three socio-emotional outcome factors which were derived using exploratory factor analysis (Emotion Moderation, Social Function and Empathy), controlling for sex, neonatal sickness, post-menstrual age at scan and social risk. Childhood Emotion Moderation scores were significantly associated with neonatal resting-state functional connectivity of the right amygdala with right parahippocampal gyrus and right middle occipital gyrus, as well as with functional connectivity of the left amygdala with the right thalamus. No significant associations were found between amygdalar resting-state functional connectivity and either Social Function or Empathy scores. The current findings show that amygdalar functional connectivity assessed at term is associated with later socio-emotional outcomes in very preterm children.

Incentive delivery timing and follow-up survey completion in a prospective cohort study of injured children: a randomized experiment comparing prepaid and postpaid incentives

Background

Retaining participants over time is a frequent challenge in research studies evaluating long-term health outcomes. This study’s objective was to compare the impact of prepaid and postpaid incentives on response to a six-month follow-up survey.

Methods

We conducted an experiment to compare response between participants randomized to receive either prepaid or postpaid cash card incentives within a multisite study of children under 15 years in age who were hospitalized for a serious, severe, or critical injury. Participants were parents or guardians of enrolled children. The primary outcome was survey response. We also examined whether demographic characteristics were associated with response and if incentive timing influenced the relationship between demographic characteristics and response. We evaluated whether incentive timing was associated with the number of calls needed for contact.

Results

The study enrolled 427 children, and parents of 420 children were included in this analysis. Follow-up survey response did not differ according to the assigned treatment arm, with the percentage of parents responding to the survey being 68.1% for the prepaid incentive and 66.7% with the postpaid incentive. Likelihood of response varied by demographics. Spanish-speaking parents and parents with lower income and lower educational attainment were less likely to respond. Parents of Hispanic/Latino children and children with Medicaid insurance were also less likely to respond. We found no relationship between the assigned incentive treatment and the demographics of respondents compared to non-respondents.

Conclusions

Prepaid and postpaid incentives can obtain similar participation in longitudinal pediatric critical care outcomes research. Incentives alone do not ensure retention of all demographic subgroups. Strategies for improving representation of hard-to-reach populations are needed to address health disparities and ensure the generalizability of studies using these results.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-021-01421-8.

Record linkage of population-based cohort data from minors with national register data: a scoping review and comparative legal analysis of four European countries

Background: The GDPR was implemented to build an overarching framework for personal data protection across the EU/EEA. Linkage of data directly collected from cohort participants, potentially serving as a prominent tool for health research, must respect data protection rules and privacy rights. Our objective was to investigate law possibilities of linking cohort data of minors with routinely collected education and health data comparing EU/EEA member states. Methods: A legal comparative analysis and scoping review was conducted of openly accessible published laws and regulations in EUR-Lex and national law databases on GDPR's implementation in Portugal, Finland, Norway, and the Netherlands and its connected national regulations purposing record linkage for health research that have been implemented up until April 30, 2021. Results: The GDPR does not ensure total uniformity in data protection legislation across member states offering flexibility for national legislation. Exceptions to process personal data, e.g., public interest and scientific research, must be laid down in EU/EEA or national law. Differences in national interpretation caused obstacles in cross-national research and record linkage: Portugal requires written consent and ethical approval; Finland allows linkage mostly without consent through the national Social and Health Data Permit Authority; Norway when based on regional ethics committee's approval and adequate information technology safeguarding confidentiality; the Netherlands mainly bases linkage on the opt-out system and Data Protection Impact Assessment. Conclusions: Though the GDPR is the most important legal framework, national legislation execution matters most when linking cohort data with routinely collected health and education data. As national interpretation varies, legal intervention balancing individual right to informational self-determination and public good is gravely needed for health research. More harmonization across EU/EEA could be helpful but should not be detrimental in those member states which already opened a leeway for registries and research for the public good without explicit consent.