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Using routine blood test results to predict the risk of death for emergency medical admissions to hospital: an external model validation study
Howes, R. Steyerberg, E.W. Richardson, D. Mohammed, Mohammed A.
Howes, R.
Steyerberg, E.W.
Richardson, D.
Mohammed, Mohammed A.
Publication Date
2016-08-02
End of Embargo
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Rights
© The Authors 2016. Published by Oxford University Press on behalf of
the Association of Physicians. This is a pre-copyedited, author-produced version of an article
accepted for publication in QJM: An International Journal of Medicine following peer review. The
version of record [Faisal M, Howes R, Steyerberg EW et al (2017) Using routine blood test results
to predict the risk of death for emergency medical admissions to hospital: an external model
validation study. QJM: An International Journal of Medicine. 110(1): 27-31.] is available online at:
https://doi.org/10.1093/qjmed/hcw110
Peer-Reviewed
Yes
Open Access status
openAccess
Accepted for publication
2016-06-22
Institution
Department
Awarded
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Additional title
Abstract
The Biochemistry and Haematology Outcome Model (BHOM) relies on the results from routine index
blood tests to predict the patient risk of death. We aimed to externally validate the BHOM model.
Method
We considered all emergency adult medical patients who were discharged from Northern
Lincolnshire and Goole (NLAG) hospital in 2014. We compared patient characteristics between NLAG
(the validation sample) and the hospital where BHOM was developed. We evaluated the predictive
performance, according to discriminative ability (with a concordance statistic, c), and calibration
(agreement between observed and predicted risk).
Result
There were 29 834 emergency discharges of which 24 696 (83%) had complete data. In comparison
with the development sample, the NLAG sample was similar in age, blood test results, but
experienced a lower mortality (4.7% vs 8.7%). When applied to NLAG, the BHOM model had good
discrimination (c-statistic 0.83 [95% CI 0.823 - 0.842]). Calibration was good overall, although the
BHOM model overpredicted for lowest (<5%, observed = 229,predicted =286) and highest (≥50%,
observed = 31, predicted = 49) risk groups, even after recalibrating for the differences in baseline
risk of death.
Conclusion
Differences in patient case-mix profile and baseline risk of death need to be considered before the
BHOM model can be used in another hospital. After re-calibrating for the baseline difference in risk
the BHOM model had good discrimination but less adequate calibration.
Version
Accepted manuscript
Citation
Faisal M, Howes R, Steyerberg EW et al (2017) Using routine blood test results to predict
the risk of death for emergency medical admissions to hospital: an external model validation
study. QJM: An International Journal of Medicine. 110(1): 27-31.
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Type
Article