Table 1

List of potential confounders for consideration in each of the statistical models

VariableData source
AgePICANet and CMP
SexPICANet and CMP
EthnicityHES, PICANet and CMP
Pre-existing comorbidities (or a proxy, eg, time in hospital in the previous year)HES, PICANet and CMP
Deprivation (IMD score)PICANet and CMP (via postcodes or LSOA)
DiagnosisPICANet, CMP and HES
Severity of illness (PIM-2/PIM-3 score and individual variables from first contact with transport team, not from referral)PICANet
Ventilated at referralPICANet
Previous admission to intensive carePICANet and CMP
Volume of referring hospitalHES or RCPCH data
Interventions prior to arrival of the transport teamPICANet
Referral location (A&E, HDU, theatre, ward etc.)PICANet
Season (winter defined as Nov to Feb)PICANet
In hours versus out of hours (to include evenings and weekends)PICANet
Interventions conducted when retrieval team arrivesPICANet
Grade of team leaderPICANet
  • CMP,¬†Case Mix Programme; HDU, High Dependency Unit; HES, Hospital Episode Statistics; IMD, Index of Multiple Deprivation; LSOA, lower super output area; PICANet,¬† Paediatric Intensive Care Audit Network; PIM, Paediatric Index of Mortality; RCPCH, Royal College of Paediatrics and Child Health.