A 'Count Outreach Warning Score' forecasts need for 'step-up' care

Objective

The number of physiological abnormalities predicts mortality [1], so we defined a positive 'Count Outreach Warning Score' (COWS) as three or more physiological abnormalities (temperature < 35°C or > 39°C; saturation < 95%; urine output below 30 ml/hour; heart rate > 99 or < 51, respiratory rate >19, mental state V/P/U [i.e. not alert]). Could COWS forecast the need for 'step-up' from normal ward care?

Method

All observations on the 79 patients present on one medical and one surgical ward over 7 days at the Chelsea and Westminster Hospital, London were scored using COWS and also the published scores EWS, MEWS and PART. A patient was predicted 'sick' by a score given a positive result on any one set of observations. Outcome was followed for 28 days. 'Stepped-up' care was prospectively defined as any of intensive care, high dependency or outreach referral or admission, cardiac arrest, death, or placement of a 'do not resuscitate' order. Confidence intervals were calculated by constant chi-squared boundaries and sensitivities compared with McNemar's test.

Results

Of 79 patients studied, 17 required 'step-up' from normal ward care (Table 1). COWS appeared more sensitive at predicting 'step-up' (P = 0.06), with similar specificity to the other scores. In four patients correctly identified by more than one score, COWS became positive 4–24 hours earlier whereas only one patient was identified by another score before identification by COWS.

Table 1

Conclusion

COWS forecast the requirement for 'step-up' care earlier and with more sensitivity than previous scores.