Issue: 2013 > January > special article

Evaluation of the threshold value for the Early Warning Score on general wards

C.R. van Rooijen, W. de Ruijter, B. van Dam


Introduction: The Early Warning Score (EWS) is used for
early detection of deteriorating vital parameters and has
been correlated with adverse outcomes. Unfortunately,
neither its value on general wards nor the optimal cut-off
value have been investigated. We aimed to find the optimal cut-off value for EWS on general wards, and investigated the possibility to raise this value from EWS ≥ 3 without compromising sensitivity too much.
Methods: From May 2010 until May 2011, EWS was
calculated from vital parameters in all patients in medical
and surgical wards in the Medical Centre Alkmaar.
Cut-off value was defined as EWS ≥ 3, unless otherwise
specified. Six responses were defined and categorised as
interventions (infusion prescription, medication changes,
ICU consultation) and other actions (no action, change
EWS cut-off value, oxygen supplementation), and it was
registered whenever the threshold was exceeded.
Results: 71,911 EWS values were obtained, 31,728 (44%) on medical wards and 40,183 (56%) on surgical wards. On medical wards, the cut-off value was exceeded 3734 times, and response was registered in 29% of the cases with 141 (12%) interventions. On surgical wards, the cut-off value was exceeded 3279 times, and response was registered in 19% of the cases with 633 (36%) interventions. Sensitivity and specificity for EWS ≥ 3 could not be calculated. For a calculated cut-off at EWS ≥ 4, sensitivity decreased to 74%. Conclusion: Raising the EWS threshold to 4 on general
wards in the hospital would lead to an unacceptable
decrease in sensitivity. Therefore, we recommend that the pre-defined cut-off should remain 3, with the possibility to personalise the threshold.