• early warning scores
• deteriorating children
• methodology
• outcomes

We can all remember individual children in whom a deterioration went unrecognised. Sometimes fatally. Our defences were little more than the pearls offered by senior colleagues of grave warning signs: ‘beware grunting in an infant’ or ‘watch out for a tachycardia after the temperature has fallen’. But this advice was unstructured, and children are so different, and their comorbidities so broad, we failed some of them. Paediatric Early Warning Systems (PEWS) are serious attempts to reduce the unacceptable and dangerous variability in this recognition and response process. Scoring systems should provide age-appropriate thresholds for concern for single parameters or aggregated abnormal physiology and prompt standardised responses. The idea has such natural appeal that PEWS use was soon advocated by a number of national bodies1 2 without evidence. This may have been a mistake. Many of the scores in widespread use were not calibrated or validated. When formally assessed, most had poor predictive performance.3 This is not a trivial problem because staff may choose not to raise an alarm in the absence of a raised score or may choose to ignore a score ‘because it never works for him/her’.

Other than optimism, the main reason for the lack of evidence was the low event rates of critical deterioration or death within individual centres. An adequately powered trial was therefore a huge challenge. Fortunately, Parshuram and colleagues took on this challenge with the study ‘Effect of a PEWS on All-Cause Mortality in Hospitalised Paediatric Patients—EPOCH’.4 This trial …