Comparison of Three Methods Estimating Baseline Creatinine For Acute Kidney Injury in Hospitalized Patients: a Multicentre Survey in Third-Level Urban Hospitals of China

Background/aims: A lack of baseline serum creatinine (SCr) data leads to underestimation of the burden caused by acute kidney injury (AKI) in developing countries. The goal of this study was to investigate the effects of various baseline SCr analysis methods on the current diagnosis of AKI in hospitalized patients.

Methods: Patients with at least one SCr value during their hospital stay between January 1, 2011 and December 31, 2012 were retrospectively included in the study. The baseline SCr was determined either by the minimum SCr (SCrMIN) or the estimated SCr using the MDRD formula (SCrGFR-75). We also used the dynamic baseline SCr (SCrdynamic) in accordance with the 7 day/48 hour time window. AKI was defined based on the KDIGO SCr criteria.

Results: Of 562,733 hospitalized patients, 350,458 (62.3%) had at least one SCr determination, and 146,185 (26.0%) had repeat SCr tests. AKI was diagnosed in 13,883 (2.5%) patients using the SCrMIN, 21,281 (3.8%) using the SCrGFR-75 and 9,288 (1.7%) using the SCrdynamic. Compared with the non-AKI patients, AKI patients had a higher in-hospital mortality rate regardless of the baseline SCr analysis method.

Conclusions: Because of the scarcity of SCr data, imputation of the baseline SCr is necessary to remedy the missing data. The detection rate of AKI varies depending on the different imputation methods. SCrGFR-75 can identify more AKI cases than the other two methods.