CREWS: improving specificity whilst maintaining sensitivity of the National Early Warning Score in patients with chronic hypoxaemia

Background: The National Early Warning Score (NEWS) is being introduced across the UK, but there are concerns about its specificity in patients with chronic hypoxaemia, such as some patients with COPD. This could lead to frequent clinically insignificant triggers and alarm fatigue.

Aims of study: To investigate whether patients with chronic hypoxaemia trigger excessively with NEWS, and to design a simple variant of NEWS for patients with chronic hypoxaemia: a Chronic Respiratory Early Warning Score (CREWS).

Methods: Data was collected from respiratory wards at two hospitals in North Wales. Components of NEWS and frequency of trigger thresholds being reached were recorded. CREWS was applied retrospectively to patients' observations.

Results: 196 admissions were analysed, including 78 for patients with chronic hypoxaemia. Patients with chronic hypoxaemia frequently exceeded trigger thresholds using NEWS during periods of stability/at discharge. Using CREWS, triggers during stability/at discharge were reduced from 32% of observations to 14% using a trigger threshold of a score greater than 6, and from 50% to 18% using a score greater than 5. All patients with chronic hypoxaemia who died within 30 days still reached CREWS trigger thresholds, and the area under receiver operated curves for NEWS and CREWS was comparable.

Conclusion: CREWS is a simple variant of NEWS for patients with chronic hypoxaemia that could reduce clinically insignificant triggers and alarm fatigue, whilst still identifying the sickest patients.