Including oxygen supplement in the early warning score: a prediction study comparing TOKS, modified TOKS and NEWS in a cohort of emergency patients

BACKGROUND: Early warning scores (EWS) are widely used in emergency departments and on general wards to detect critical illness and deterioration. TOKS ("Tidlig Opsporing af Kritisk Sygdom") is an early warning score used in Central Denmark Region to monitor hospitalized patients. The objective of this study is to investigate whether inclusion of supplement in the TOKS algorithm (modified TOKS; mTOKS), would improve the ability to predict 7-day mortality. Secondarily, we compare the discriminatory ability between TOKS, mTOKS and the National Early Warning Score (NEWS).

METHODS: This is a prediction study including a cohort of adult patients who attended an emergency department in Central Denmark Region during a 3-month period in 2015. The discriminatory ability of TOKS, mTOKS and NEWS was evaluated by calculating the area under the receiver operating characteristics- curve (AUROC) with 7-day mortality as outcome. mTOKS was defined by adding 2 points for oxygen supplement to the normal TOKS score.

RESULTS: 18.853 patients were included. AUROC for TOKS: 0,78 (95%-CI: 0,76-0,81). AUROC for mTOKS: 0,81 (95 %-CI: 0,78-0,83). AUROC for NEWS: 0,83 (95%-CI: 0,80-0,85). The predictive ability of all three early warning scores are statistically significantly different from each other (p-value < 0,01).

CONCLUSION: The discriminatory ability of TOKS improved statistically by including oxygen supplement. All models showed moderate to good discriminatory ability.