Original Article| Volume 51, P25-28, May 2018

External validation of a decision tree early warning score using only laboratory data: A retrospective review of prospectively collected data

Published:February 14, 2018DOI:


      • Acceptable ability to identify patients at risk of in-hospital mortality
      • Compatible to other EWS
      • Accurate for most major disease categories studied separately



      Early warning scores (EWS) have been developed to identify the degree of illness severity among acutely ill patients. One system, The Laboratory Decision Tree Early Warning Score (LDT-EWS) is wholly laboratory data based. Laboratory data was used in the development of a rare computerized method, developing a decision tree analysis. This article externally validates LDT-EWS, which is obligatory for an EWS before clinical use.


      We conducted a retrospective review of prospectively collected data based on a time limited sample of all patients admitted through the medical admission unit (MAU) on a Danish secondary hospital. All consecutive adult patients admitted from 2 October 2008 until 19 February 2009, and from 23 February 2010 until 26 May 2010, were included. Validation was made by calculating the discriminatory power as area under the receiver-operating curve (AUROC) and calibration (precision) as Hosmer-Lemeshow Goodness of fit test.


      A total of 5858 patients were admitted and 4902 included (83.7%). In-hospital mortality in our final dataset (n = 4902) was 3.5%. Discriminatory power (95% CI), identifying in-hospital death was 0.809 (0.777–0.842). Calibration was good with a goodness-of-fit test of X2 = 5.37 (7 degrees of freedom), p = 0.62.


      LDT-EWS has acceptable ability to identify patients at high risk of dying during hospitalization with good precision. Further studies performing impact analysis are required before this score should be implemented in clinical practice.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to European Journal of Internal Medicine
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Brabrand M.
        • Lassen A.T.
        • Knudsen T.
        • Hallas J.
        Seven-day mortality can be predicted in medical patients by blood pressure, age, respiratory rate, loss of independence, and peripheral oxygen saturation (the PARIS score): a prospective cohort study with external validation.
        PLoS One. 2015; 10e0122480
        • Smith G.B.
        • Prytherch D.R.
        • Meredith P.
        • Schmidt P.E.
        • Featherstone P.I.
        The ability of the National Early Warning Score (NEWS) to discriminate patients at risk of early cardiac arrest, unanticipated intensive care unit admission, and death.
        Resuscitation. 2013; 84: 465-470
        • Brabrand M.
        • Knudsen T.
        • Hallas J.
        Identifying admitted patients at risk of dying: a prospective observational validation of four biochemical scoring systems.
        BMJ Open. 2013; 3
        • Jarvis S.W.
        • Kovacs C.
        • Badriyah T.
        • Briggs J.
        • Mohammed M.A.
        • Meredith P.
        • et al.
        Development and validation of a decision tree early warning score based on routine laboratory test results for the discrimination of hospital mortality in emergency medical admissions.
        Resuscitation. 2013; 84: 1494-1499
        • McGinn T.G.
        • Guyatt G.H.
        • Wyer P.C.
        • Naylor C.D.
        • Stiell I.G.
        • Richardson W.S.
        Users' guides to the medical literature: XXII: how to use articles about clinical decision rules. Evidence-Based Medicine Working Group.
        JAMA. 2000; 284: 79-84
        • Paterson R.
        • MacLeod D.C.
        • Thetford D.
        • Beattie A.
        • Graham C.
        • Lam S.
        • et al.
        Prediction of in-hospital mortality and length of stay using an early warning scoring system: clinical audit.
        Clin Med (Lond). 2006; 6: 281-284
        • Collins G.S.
        • Reitsma J.B.
        • Altman D.G.
        • Moons K.G.
        Transparent reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis (TRIPOD).
        Ann. Intern. Med. 2015; 162: 735-736
        • Schmidt M.
        • Pedersen L.
        • Sorensen H.T.
        The Danish Civil Registration System as a tool in epidemiology.
        Eur. J. Epidemiol. 2014; 29: 541-549
        • David W.
        • Hosmer J.
        • Lemeshow Stanley
        • Sturdivant Rodney X.
        Applied Logistic Regression.
        Third Edition. Wiley Online Library, 2013
        • Charlson M.E.
        • Pompei P.
        • Ales K.L.
        • CR MacKenzie
        A new method of classifying prognostic comorbidity in longitudinal studies: development and validation.
        J. Chronic Dis. 1987; 40: 373-383
        • Kellett J.
        • Kim A.
        Validation of an abbreviated Vitalpac Early Warning Score (ViEWS) in 75,419 consecutive admissions to a Canadian regional hospital.
        Resuscitation. 2012; 83: 297-302
        • Brabrand M.
        • Folkestad L.
        • Clausen N.G.
        • Knudsen T.
        • Hallas J.
        Risk scoring systems for adults admitted to the emergency department: a systematic review.
        Scand J Trauma Resusc Emerg Med. 2010; 18: 8