Background Capacity and demand for paediatric critical care are growing in many resource-constrained contexts. However, tools to support resource stewardship and promote sustainability of critical care services are lacking. Methods This study assessed the ability of nine severity scores to risk stratify children admitted to a paediatric intensive care unit (PICU) in Siem Reap, northern Cambodia. It then developed a bespoke clinical prediction model to enable risk stratification in resource-constrained PICU contexts. The primary outcome was death during PICU admission. Results 1,550 consecutive PICU admissions were included, of which 97 (6.3%) died. Most existing severity scores achieved comparable discrimination (area under the receiver operating characteristic curves [AUCs] 0.71-0.76) but only three scores demonstrated moderate diagnostic utility for triaging admissions into high- and low-risk groups (positive likelihood ratios 2.65-2.97 and negative likelihood ratios 0.40-0.46). The newly derived model outperformed all existing severity scores (AUC 0.84, 95% CI 0.80-0.88; p < 0.001). Using one particular threshold, the model classified 13.0% of admissions as high-risk, amongst which probability of mortality was almost ten-fold greater than admissions triaged as low-risk (PLR 5.75; 95% CI 4.57-7.23 and NLR 0.47; 95% CI 0.37-0.59). Decision curve analyses indicated that the model would be superior to all existing severity scores and could provide utility across the range of clinically plausible decision thresholds. Conclusions Existing paediatric severity scores have limited potential as risk stratification tools in resource-constrained PICUs. If validated, the prediction model developed herein would provide a readily implementable mechanism to support triage of critically ill children on admission to PICU and could be tailored to suit a variety of contexts where resource prioritisation is important.

The authors have declared no competing interest.

This research was funded by the UK Wellcome Trust [219644/Z/19/Z]. RPS acknowledges part support from the NIHR Applied Research Collaboration Oxford & Thames Valley, the NIHR Oxford Medtech and In-Vitro Diagnostics Co-operative and the Oxford Martin School. CK is supported by a Wellcome Trust/Royal Society Sir Henry Dale Fellowship [211182/Z/18/Z]. For the purpose of open access, the author has applied a CC BY public copyright license to any Author Accepted Manuscript version arising from this submission.

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The study was approved by the Angkor Hospital for Children Research Committee (AHC 0656/20), Cambodian National Ethics Committee for Health Research (NECHR 257), and the Oxford Tropical Research and Ethics Committee (OxTREC 565-20),

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