Abstract
Objective: To estimate the magnitude of the correlation between neonatal outcomes of twins and demonstrate how this information can be used in the design of randomised controlled trials (RCTs) in women with twin pregnancies. Design: Secondary analysis of data from 12 RCTs. Setting: Obstetric care in multiple countries, 2004–2012. Population or sample: 4504 twin pairs born to women who participated in RCTs to assess treatments given during pregnancy. Methods: Intraclass correlation coefficients (ICCs) were estimated using log-binomial and linear models. Main outcome measures: Perinatal death, respiratory distress syndrome, bronchopulmonary dysplasia, intraventricular haemorrhage, necrotising enterocolitis, sepsis, neonatal intensive care unit admission, birthweight, low birthweight and two composite measures of adverse neonatal outcome. Results: ICCs for the composite measures of adverse neonatal outcome were all above 0.5, indicating moderate to strong correlation between adverse outcomes of twins. For individual neonatal outcomes, median ICCs across trials ranged from 0.13 to 0.79 depending on the outcome. An example illustrates how ICCs can be used in sample size calculations for RCTs in women with twin pregnancies. Conclusions: The correlation between neonatal outcomes of twins varies considerably between outcomes and may be lower than expected. Our ICC estimates can be used for designing and analysing RCTs that recruit women with twin pregnancies and for performing meta-analyses that include such RCTs. Researchers are encouraged to report ICCs for neonatal outcomes in twins in their own RCTs. Tweetable abstract: Correlation between neonatal outcomes of twins depends on the outcome and may be lower than expected.
| Original language | English |
|---|---|
| Pages (from-to) | 1406-1413 |
| Number of pages | 8 |
| Journal | BJOG: An International Journal of Obstetrics and Gynaecology |
| Volume | 125 |
| Issue number | 11 |
| DOIs | |
| Publication status | Published - Oct 2018 |
Bibliographical note
Funding Information:Lisa Yelland was supported by an Australian National Health and Medical Research Council Early Career Fellowship (ID 1052388). This research was supported by a Women’s and Children’s Hospital Foundation Research Project Grant. The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript.
Funding Information:
Lisa Yelland was supported by an Australian National Health and Medical Research Council Early Career Fellowship (ID 1052388). This research was supported by a Women's and Children's Hospital Foundation Research Project Grant. The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript. We are grateful to the trial investigators, research staff, and participants who were involved with each of the trials contributing data to this study. In particular, we acknowledge the STOPPIT study team for the Norman trial; the MEDNAX Center for Research Education and Quality and use of its data from the Combs trial; the assistance of the NICHD, the MFMU Network and the STTARS Protocol Subcommittee in making the database available for the Rouse trial; and the following trial investigators who granted permission to use data from their trials: Jane Norman, Stephen Wood, Mona Aboulghar, Kimberly Maurel, Sophie Liem, and Elcin Cetingoz. The contents of this report represent the views of the authors and do not represent the views of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network or the National Institutes of Health.
Publisher Copyright:
© 2018 Royal College of Obstetricians and Gynaecologists
Keywords
- Bayesian analysis
- intraclass correlation coefficient
- meta-analysis
- power
- sample size
- twins
ASJC Scopus subject areas
- Obstetrics and Gynaecology