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. 2017 Mar 8;7(3):e013511.
doi: 10.1136/bmjopen-2016-013511.

Predicting AKI in emergency admissions: an external validation study of the acute kidney injury prediction score (APS)

L E Hodgson  1   2 , B D Dimitrov  1 , P J Roderick  1 , R Venn  2 , L G Forni  3   4
Affiliations

Predicting AKI in emergency admissions: an external validation study of the acute kidney injury prediction score (APS)

L E Hodgson et al. BMJ Open. .

Abstract

Objectives: Hospital-acquired acute kidney injury (HA-AKI) is associated with a high risk of mortality. Prediction models or rules may identify those most at risk of HA-AKI. This study externally validated one of the few clinical prediction rules (CPRs) derived in a general medicine cohort using clinical information and data from an acute hospitals electronic system on admission: the acute kidney injury prediction score (APS).

Design, setting and participants: External validation in a single UK non-specialist acute hospital (2013-2015, 12 554 episodes); four cohorts: adult medical and general surgical populations, with and without a known preadmission baseline serum creatinine (SCr).

Methods: Performance assessed by discrimination using area under the receiver operating characteristic curves (AUCROC) and calibration.

Results: HA-AKI incidence within 7 days (kidney disease: improving global outcomes (KDIGO) change in SCr) was 8.1% (n=409) of medical patients with known baseline SCr, 6.6% (n=141) in those without a baseline, 4.9% (n=204) in surgical patients with baseline and 4% (n=49) in those without. Across the four cohorts AUCROC were: medical with known baseline 0.65 (95% CIs 0.62 to 0.67) and no baseline 0.71 (0.67 to 0.75), surgical with baseline 0.66 (0.62 to 0.70) and no baseline 0.68 (0.58 to 0.75). For calibration, in medicine and surgical cohorts with baseline SCr, Hosmer-Lemeshow p values were non-significant, suggesting acceptable calibration. In the medical cohort, at a cut-off of five points on the APS to predict HA-AKI, positive predictive value was 16% (13-18%) and negative predictive value 94% (93-94%). Of medical patients with HA-AKI, those with an APS ≥5 had a significantly increased risk of death (28% vs 18%, OR 1.8 (95% CI 1.1 to 2.9), p=0.015).

Conclusions: On external validation the APS on admission shows moderate discrimination and acceptable calibration to predict HA-AKI and may be useful as a severity marker when HA-AKI occurs. Harnessing linked data from primary care may be one way to achieve more accurate risk prediction.

Keywords: GENERAL MEDICINE (see Internal Medicine).

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Conflict of interest statement

Competing interests: All authors declare that the results presented in this paper have not been published previously in whole or part. All authors have completed the Unified Competing Interest form at http://www.icmje.org/coi_disclosure.pdf and declare that all have no relationships with companies that might have an interest in the submitted work in the previous 3 years; their spouses, partners, or children have no financial relationships that may be relevant to the submitted work; and have no non-financial interests that may be relevant to the submitted work.

Figures

Figure 1
Figure 1
Consort study flow chart. HA-AKI, hospital-acquired acute kidney injury; SCr, serum creatinine.
Figure 2
Figure 2
Area under the receiver operating characteristic curves for APS to predict HA-AKI. A: medicine with known baseline SCr 0.65 (95% CI 0.62 to 0.67); B: medicine no baseline SCr 0.71 (95% CI 0.67 to 0.75); C: Surgery with known baseline SCr 0.66 (95% CI 0.62 to 0.70); D: surgery without a baseline SCr 0.67 (95% CI 0.58 to 0.75). APS, acute kidney injury (AKI) prediction score; HA-AKI, hospital-acquired AKI; SCr, serum creatinine.
Figure 3
Figure 3
Calibration plots of predicted probabilities versus observed rates of HA-AKI. Predicted probabilities versus observed rates (HA-AKI) at each level of the APS score in the medical (TOP) and surgical (BOTTOM) cohorts with a known baseline creatinine. APS, acute kidney injury (AKI) prediction score; HA-AKI, hospital-acquired AKI.
See this image and copyright information in PMC

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