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Differences in Paediatric intensive care mortality by biological sex: a study of English PICUs using linked
Ofran Almossawi1,2, Bianca L De Stavola1, Katie Harron1
1UCL Great Ormond Street Institute of Child Health, London, WC1N 1EH UK.
Insights
In Paediatric Intensive Care Units (PICUs), girls face higher mortality than boys, reversing general population trends. This study confirms a causal link between female sex and increased PICU mortality risk.
Area of Science:
- Pediatric Critical Care Medicine
- Epidemiology
- Biostatistics
Background:
- General population data show higher mortality rates in boys compared to girls.
- The impact of biological sex on outcomes in pediatric intensive care settings is not fully understood.
- Previous studies may not have adequately accounted for confounding factors in analyzing sex-based mortality differences.
Purpose of the Study:
- To investigate a potential causal relationship between biological sex and mortality risk in children admitted to Paediatric Intensive Care Units (PICUs).
- To quantify the excess mortality risk for females in PICU compared to a hypothetical scenario where they were male.
Main Methods:
- A multi-center, population-based cohort study utilizing English PICU data from 2010-2019.
- Employed the potential outcomes framework and doubly robust statistical methods to establish causality.
- Analyzed linked PICU and hospital records for children aged 0-8 years, with biological sex as the primary exposure.
Main Results:
- The study included 48,500 children (42.1% female, 57.9% male).
- Overall mortality during the first PICU admission was 3.63% (1,760 deaths).
- The estimated excess mortality risk for females in PICU (Average Treatment effect in the Treated) was 0.31% (95% CI 0.01-0.61), indicating higher mortality for girls.
Conclusions:
- Contrary to general population trends, female children experience higher mortality in PICUs.
- Doubly robust causal methods confirm a statistically significant causal link between being female and increased PICU mortality.
- These findings challenge the assumption of uniform responses to critical illness and treatment across sexes in pre-pubertal children, necessitating further investigation.
Objective:
To determine if there is a causal relationship between sex and mortality in Paediatric Intensive Care Units (PICUs).
Methods:
A multi-centre, population-based cohort study of English PICUs, designed using the potential outcomes framework and doubly robust methods. Participants were children aged 0 to 8 years with at least one admission to PICU between January 2010 and December 2019, with linked PICU and hospital records. The exposure was biological sex, and the main outcome was the causal difference in mortality between females in PICU and their counterfactual mortality if these females were hypothetically male (Average Treatment effect in the Treated; ATT).
Results:
There were 48,500 children, of whom 20,412 (42.1%) were females and 28,088 (57.9%) were males and with a median age at first PICU admission of 0.5 (IQR 0.08-2.02) years. During the first admission, 1,760 (3.63%) children died; of whom, 777/20,412 (3.81%) were female and 983/28,088 (3.50%) were male. The doubly robust estimated causal mortality risk difference captured by the ATT (i.e. excess mortality for girls in PICU), was 0.31% (95% CI 0.01-0.61).
Conclusions:
Although boys have a higher rate of death than girls by age in the general population, this mortality trend is reversed in PICU. Evidence of this increased female mortality persists after applying doubly robust causal methods, indicating a causal link. The supposition that all pre-pubertal children have the same responses to critical illness and their management should be re-examined.
Supplementary Information:
The online version contains supplementary material available at 10.1007/s44253-026-00130-8.
