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01.12.2016 | Research article | Ausgabe 1/2016 Open Access

BMC Nephrology 1/2016

The comparison of the commonly used surrogates for baseline renal function in acute kidney injury diagnosis and staging

BMC Nephrology > Ausgabe 1/2016
Charat Thongprayoon, Wisit Cheungpasitporn, Andrew M. Harrison, Wonngarm Kittanamongkolchai, Patompong Ungprasert, Narat Srivali, Abbasali Akhoundi, Kianoush B. Kashani
Wichtige Hinweise

Electronic supplementary material

The online version of this article (doi:10.​1186/​s12882-016-0220-z) contains supplementary material, which is available to authorized users.

Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

CT had full access to the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. CT, WC, and KBK designed the study. CT, WC, WK, PU, and NS collected data. CT, WC, and AMH analyzed and interpreted data, CT, WC, AMH, and KBK drafted and critically revised the manuscript for important intellectual content. KBK supervised all critical parts of the study. All authors read and approved the final manuscript.



Baseline serum creatinine (SCr) level is frequently not measured in clinical practice. The aim of this study was to investigate the effect of various methods of baseline SCr determination measurement on accuracy of acute kidney injury (AKI) diagnosis in critically ill patients.


This was a retrospective cohort study. All adult intensive care unit (ICU) patients admitted at a tertiary referral hospital from January 1, 2011 through December 31, 2011, with at least one measured SCr value during ICU stay, were included in this study. The baseline SCr was considered either an admission SCr (SCrADM) or an estimated SCr, using MDRD formula, based on an assumed glomerular filtration rate (GFR) of 75 ml/min/1.73 m2 (SCrGFR-75). Determination of AKI was based on the KDIGO SCr criterion. Propensity score to predict the likelihood of missing SCr was used to generate a simulated cohort of 3566 patients with baseline outpatient SCr, who had similar characteristics with patients whose outpatient SCr was not available.


Of 7772 patients, 3504 (45.1 %) did not have baseline outpatient SCr. Among patients without baseline outpatient SCr, AKI was detected in 571 (16.3 %) using the SCrADM and 997 (28.4 %) using SCrGFR-75 (p < .001). Compared with non-AKI patients, patients who met AKI only by SCrADM, but not SCrGFR-75, were significantly associated with 60-day mortality (OR 2.90; 95 % CI 1.66–4.87), whereas patients who met AKI only by SCrGFR-75, but not SCrADM, had a non-significant increase in 60-day mortality risk (OR 1.33; 95 % CI 0.94–1.88). In a simulated cohort of patients with baseline outpatient SCr, SCrGFR-75 yielded a higher sensitivity (77.2 vs. 50.5 %) and lower specificity (87.8 vs. 94.8 %) for the AKI diagnosis in comparison with SCrADM.


When baseline outpatient SCr was not available, using SCrGFR-75 as surrogate for baseline SCr was found to be more sensitive but less specific for AKI diagnosis compared with using SCrADM. This resulted in higher incidence of AKI with larger likelihood of false-positive cases.
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