Predictors

Vital sign sets (see above) were recorded using SEND/VitalPAC^™. Where the patient’s conscious level had been assessed only using the Glasgow Coma Scale (GCS), we converted GCS to an AVPU equivalent²¹. Vital signs were then assigned weights for NEWS and NEWS2 scores (see appendix A1). The sum of the weights (aggregate score) results in the NEWS and NEWS2 value for each observation set. SEND (OUH) uses a modified EWS, CEWS²³, which assigns increasing weights to SpO₂ values less than 94% and does not weight SpO₂ values of 94% or above. Clinical staff entering vital signs data were therefore unaware of NEWS or NEWS2 scores. VitalPAC^™ (PH) uses NEWS. To allow comparison with published analyses of NEWS^{22, 24}, and in line with previous vital-signs-based EWS research^{25, 26, 27, 28}, each vital sign set was analysed as independently associated with the outcome.