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Correlation between neonatal outcomes of twins depends on the outcome: secondary analysis of twelve randomised controlled trials
Author(s) -
Yelland LN,
Schuit E,
Zamora J,
Middleton PF,
Lim AC,
Nassar AH,
Rode L,
Serra V,
Thom EA,
Vayssière C,
Mol BWJ,
Gates S
Publication year - 2018
Publication title -
bjog: an international journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.157
H-Index - 164
eISSN - 1471-0528
pISSN - 1470-0328
DOI - 10.1111/1471-0528.15292
Subject(s) - randomized controlled trial , medicine , bronchopulmonary dysplasia , neonatal intensive care unit , intraclass correlation , respiratory distress , pediatrics , neonatal sepsis , obstetrics , population , pregnancy , gestational age , sepsis , surgery , clinical psychology , environmental health , biology , genetics , psychometrics
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 ( RCT s) in women with twin pregnancies. Design Secondary analysis of data from 12 RCT s. Setting Obstetric care in multiple countries, 2004–2012. Population or sample 4504 twin pairs born to women who participated in RCT s to assess treatments given during pregnancy. Methods Intraclass correlation coefficients ( ICC s) 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 ICC s 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 ICC s across trials ranged from 0.13 to 0.79 depending on the outcome. An example illustrates how ICC s can be used in sample size calculations for RCT s 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 RCT s that recruit women with twin pregnancies and for performing meta‐analyses that include such RCT s. Researchers are encouraged to report ICC s for neonatal outcomes in twins in their own RCT s. Tweetable abstract Correlation between neonatal outcomes of twins depends on the outcome and may be lower than expected.