Calibration of the paediatric index of mortality in UK paediatric intensive care units

Pearson et al should be congratulated on successfully collecting the data required for calculating the PIM Score on 7253 children admitted to 5 UK paediatric intensive care units (PICUs). It is reassuring to note that the authors did not find any systematic differences between these five units in terms of their standardised mortality ratios. Leaving aside the controversies involved in cross country comparisons, it is further pleasing that they appear to conclude that mortality following admission for paediatric intensive care in 1998–99 is less than it was in 1994– 95. 3 The current results imply that 78 more children have survived following treatment in these 5 PICUs than were predicted by the 1994–95 PIM derivation model. Before this can be considered a major clinical advance, it is important to consider the health status of the additional survivors. Very different conclusions might be drawn if the additional children who survived have a very poor health status than if they have a very good health status. The United Kingdom Paediatric Intensive Care Outcome Study (UK PICOS) was set up in response to the “Paediatric Intensive Care: A framework for the future” document and a joint United Kingdom Medical Research Council and Department of Health working paper. 5 Both these publications recognised that, as mortality following paediatric intensive care is less than 10%, morbidity or health status may be a more important outcome of paediatric intensive care than mortality. UK PICOS is currently collecting health status measurements of children who survive following admission for paediatric intensive care in a representative sample of 21 UK PICUs. By seeking to differentiate between the survivors of paediatric intensive care UK PICOS may lead to a risk adjustment method for health status in addition to mortality. Furthermore, UK PICOS has the potential to provide the methodology to enable cost effectiveness studies to be set up in paediatric intensive care. In the longer term this will allow organisational structures, service management, and new interventions in paediatric intensive care to be evaluated in a more rigorous manner than at present. Further details of UK PICOS are available at www.shef.ac.uk/∼scharr/ukpicos.