Intracluster correlation coefficients for neonatal trials: an analysis of national population level clinical data.
5 affiliations
- 1Neonatal Medicine, School of Public Health, Faculty of Medicine, Imperial College London, Chelsea and Westminster Hospital Campus, 369 Fulham Road, London, SW10 9NH, UK.
- 2Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London, EC1V 2PD, UK.
- 3Cicely Saunders Institute of Palliative Care, Policy and Rehabilitation, King's College London, Bessemer Road, London, SE5 9PJ, UK.
- 4Neonatal Medicine, School of Public Health, Faculty of Medicine, Imperial College London, Chelsea and Westminster Hospital Campus, 369 Fulham Road, London, SW10 9NH, UK. [email protected].
- 5Centre for Paediatrics and Child Health, Imperial College, London, UK. [email protected].
Abstract
Background
Clustering of outcomes occurs naturally in neonatal data due to multiple births clustered by mother and infants clustered within the neonatal unit administering their care. Estimating these cluster effects is important for neonatal study design and impacts upon sample sizes for neonatal trials.Methods
We analysed retrospective data from all neonatal admissions in England and Wales between January 2016 and January 2020 held in the National Neonatal Research Database. Intracluster correlation coefficients (ICCs) and their 95% confidence intervals were calculated for core neonatal outcomes and those commonly used in trials, at the level of both the neonatal unit and mother. Results were stratified by gestational age and neonatal unit level of birth. To illustrate the impact of clustering, the design effect was estimated for a theoretical cluster trial.Results
Intracluster correlation coefficients varied between outcomes and gestational age groups. Neonatal unit level intracluster correlation coefficients were low for mortality (0.0054, 95% CI 0.0039, 0.0068) and other core outcomes (severe necrotising enterocolitis 0.0042, 95% CI 0.0020, 0.0063) and were higher for outcomes related to care delivery (duration of intensive care 0.0237, 95% CI 0.0177, 0.0298; duration receiving parenteral nutrition 0.0265, 95% CI 0.0197, 0.0332). Gestation at birth was inversely correlated with neonatal unit ICC estimates. At the level of the mother, ICC estimates were generally larger, especially for preterm infants.Conclusions
We have estimated ICCs for key neonatal outcomes at the level of both neonatal unit and mother with high precision using national, population-level routinely recorded data. These ICC estimates can be used to inform future neonatal studies and sample size calculations for neonatal trials.
Related
- Do I Even Need a Multilevel Model? Negligible Effect Significance Testing for Intraclass Correlation Coefficients
- TwinPoSI: Statistical Twins for Powerful Post-Selection Inference on Population-Based Regression Coefficients
- Spatial Kernel Restricted Canonical Correlation Analysis: Population Targets, Identifiability, and Stability
- Sex differences in early and late neonatal all-cause mortality and disease burden in Kazakhstan, 2010–2023: A population-based analysis of Global Burden of Disease estimates
- Formality theorem with coefficients in a module
BibTeX
@article{jawad2026intracluster,
title = {{Intracluster correlation coefficients for neonatal trials: an analysis of national population level clinical data.}},
author = {S Jawad and A T Prevost and C Gale and C Gale},
journal = {Trials},
year = {2026},
month = jul,
doi = {10.1186/s13063-026-09893-z},
url = {https://europepmc.org/article/MED/42894246},
note = {CC BY},
}
RIS
TY - JOUR
TI - Intracluster correlation coefficients for neonatal trials: an analysis of national population level clinical data.
AU - S Jawad
AU - A T Prevost
AU - C Gale
AU - C Gale
PY - 2026
DA - 2026/07/01
JO - Trials
DO - 10.1186/s13063-026-09893-z
UR - https://europepmc.org/article/MED/42894246
AB - Background Clustering of outcomes occurs naturally in neonatal data due to multiple births clustered by mother and infants clustered within the neonatal unit administering their care. Estimating these cluster effects is important for neonatal study design and impacts upon sample sizes for neonatal trials.Methods We analysed retrospective data from all neonatal admissions in England and Wales between January 2016 and January 2020 held in the National Neonatal Research Database. Intracluster correlation coefficients (ICCs) and their 95% confidence intervals were calculated for core neonatal outcomes and those commonly used in trials, at the level of both the neonatal unit and mother. Results were stratified by gestational age and neonatal unit level of birth. To illustrate the impact of clustering, the design effect was estimated for a theoretical cluster trial.Results Intracluster correlation coefficients varied between outcomes and gestational age groups. Neonatal unit level intracluster correlation coefficients were low for mortality (0.0054, 95% CI 0.0039, 0.0068) and other core outcomes (severe necrotising enterocolitis 0.0042, 95% CI 0.0020, 0.0063) and were higher for outcomes related to care delivery (duration of intensive care 0.0237, 95% CI 0.0177, 0.0298; duration receiving parenteral nutrition 0.0265, 95% CI 0.0197, 0.0332). Gestation at birth was inversely correlated with neonatal unit ICC estimates. At the level of the mother, ICC estimates were generally larger, especially for preterm infants.Conclusions We have estimated ICCs for key neonatal outcomes at the level of both neonatal unit and mother with high precision using national, population-level routinely recorded data. These ICC estimates can be used to inform future neonatal studies and sample size calculations for neonatal trials.
SN - 1745-6215
ER -