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Weight-for-age distribution and case-mix adjusted outcomes of 14,307 paediatric intensive care admissions
Nicholas J Prince1, Katherine L Brown, Teumzghi F Mebrahtu
1Respiratory Critical Care and Anaesthesia Unit, Institute of Child Health, University College London, London, WC1N 1EH, UK, nprince@nhs.net.
Insights
Children in paediatric intensive care (PIC) are underweight compared to UK averages. Extreme weight deviations, both underweight and overweight, increase mortality risk, with mild overweight showing the lowest risk.
Area of Science:
- Pediatric Intensive Care Medicine
- Clinical Epidemiology
- Nutritional Science
Background:
- Paediatric intensive care (PIC) admissions represent a vulnerable population with unique physiological characteristics.
- Understanding weight distribution in PIC is crucial for assessing nutritional status and predicting outcomes.
- Existing UK reference data may not accurately reflect the weight-for-age of children requiring intensive care.
Purpose of the Study:
- To compare the weight-for-age distribution of PIC admissions against the general UK population.
- To investigate whether admission weight-for-age is an independent predictor of mortality in critically ill children.
- To identify specific weight categories associated with increased mortality risk.
Main Methods:
- Calculation of weight-for-age standard deviation scores (SDS) for 12,458 PIC admissions (March 2003-December 2011).
- Categorization of children into nine SDS groups to analyze mortality patterns.
- Application of standardized mortality ratios (SMR) and logistic regression to assess risk-adjusted mortality.
Main Results:
- The PIC population exhibited a mean weight-for-age significantly lower than the UK reference mean (1.04 SD below, p < 0.0001).
- A U-shaped association was observed between weight-for-age and risk-adjusted mortality, with highest mortality at extreme underweight (SDS < -3.5) and extreme overweight (SDS > +3.5).
- Admission weight-for-age, age, gender, and ethnicity were identified as independent risk factors for mortality. South Asian and 'other' ethnic groups faced significantly higher mortality risks.
Conclusions:
- The weight distribution in the PIC population is skewed towards lower weight-for-age compared to the general UK population, with underweight extremes being over-represented.
- Weight-for-age at admission is a significant independent risk factor for mortality in critically ill children.
- Further research is warranted to explore the impact of malnutrition and the reasons behind ethnic disparities in mortality risk within PIC settings.
Aims:
To determine whether the paediatric intensive care (PIC) population weight distribution differs from the UK reference population and whether weight-for-age at admission is an independent risk factor for mortality.
Methods:
Admission weight-for-age standard deviation scores (SDS) were calculated for all PIC admissions (March 2003-December 2011) to Great Ormond Street Hospital: this is the number of standard deviations (SD) between a child's weight and the UK mean weight-for-age. Categorised into nine SDS groups, standardised mortality ratios (SMR) and logistic regression were used to assess the relationship between weight-for-age at admission and risk-adjusted mortality.
Results:
Out of 12,458 admissions, mean weight-for-age was 1.04 SD below the UK reference population mean (p < 0.0001). Based on 942 deaths, risk-adjusted mortality was lowest in those with mild-to-moderately raised weight-for-age (SDS 0.5-2.5) and highest in children with extreme under- or overweight (SDS < -3.5 and SDS > +3.5). Logistic regression indicated that age, gender, ethnicity and weight-for-age are independent risk factors for mortality. South Asian and 'other' ethnicities had significantly increased risk of death compared to children of white and black ethnic origin.
Conclusion:
The PIC population mean weight-for-age is significantly lower than the UK reference mean. The extremes of weight-for-age are over-represented, especially underweight. Weight-for-age at admission is an independent risk factor for mortality. A U-shaped association between weight and risk-adjusted mortality exists, with the lowest risk of death in children who are mild-to-moderately overweight. Future studies should determine the impact of malnutrition on risk-adjusted mortality and investigate the aetiology of risk disparities with ethnicity.
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