Detection of patients with acute kidney injury by the clinical laboratory using rises in serum creatinine: comparison of proposed definitions and a laboratory delta check

Abstract

Background: Timely detection of acute kidney injury (AKI) in hospital patients has been hampered by the multiple definitions of AKI and difficulties applying their criteria. A laboratory delta check may provide an effective means of detecting patients developing AKI. This study compared three of the proposed AKI definitions and a delta check to detect AKI using serum creatinine results of hospital inpatients. Methods: Serum creatinine results for 2822 inpatients were gathered retrospectively from the clinical biochemistry database. All serum creatinine results within 30 d of admission were included for each patient and assessed for AKI according to four criteria: Risk, Injury, Failure (RIFLE), Acute Kidney Injury Network (AKIN), Waikar & Bonventre or a delta check (increase of .26 mmol/L between two successive values). Results: A total of 149 (11.3%) patients were defined as having AKI by at least one of the four criteria. Different populations of patients were identified by each criterion. The number of patients identified and the incidence of AKI were as follows: RIFLE 94 (7.1%), AKIN 125 (9.5%), Waikar & Bonventre 100 (7.6%) and delta check 146 (11.1%). The delta check detected 132 (98%) of all 135 cases detected by the other three criteria. A further 14 patients were detected solely by the delta check. Conclusions: The different definitions proposed for AKI detect different populations of patients. A laboratory delta check detected 98% of all the patients identified by AKIN, RIFLE and Waikar & Bonventre combined and could therefore provide a practical way of detecting AKI patients.

Pre-Stage Acute Kidney Injury Can Predict Mortality and Medical Costs in Hospitalized Patients

“…The reference change value of serum creatinine, which might reflect normal laboratory analytic variability and biological within-individual variability, is estimated at 14–17% [26]. Therefore, small increases in serum creatinine might reflect normal variability in serum creatinine within the reference range.…”

Making better use of differences in serial laboratory results

“…Although there are a number of ways to select the delta check values, 4 setting is usually done somewhat empirically with the aim of detecting major blunders, such as the submission for analysis of samples from different patients but which have been labelled with a single identifier, but not flagging too many cases for further time-consuming, but often inconsequential, investigation by professionals in laboratory medicine. Garner et al 3 selected the delta check value of an increase of 26 mmol/L in serum creatinine for the detection of AKI using the criteria set in the AKIN and Waikar & Bonventre strategies for diagnosis of Stage 1 AKI, and this simple approach did appear to be potentially clinically useful. Others have proposed similarly simple numerical criteria for interpretation of differences in serial results: recent examples include that reductions of at least 25% and 50% are considered minimal and partial responses to treatment for monoclonal proteins in serum 5 and a change of 20% is significant for serum troponin.…”

Using the Kinetic Estimating Glomerular Filtration Rate Equation for Estimating Glomerular Filtration Rate and Detecting Acute Kidney Injury: A Pilot Study

“…If the laboratory is able to create an alert for AKI in the reporting system based on percentage change in KeGFR using the time stamp on the Cr assay request, this might help in the timely detection of AKI. The Delta check method uses a fixed reference change value (RCV) for detecting AKI and has the potential to alert the clinician similar to the lab-based method [12]. However, it recognises the absolute or relative change in Cr level but does not detect the rate of change of Cr.…”

“…This method detected more AKI episodes than the KeGFR method in our study, and in turn failed to detect episodes of AKI detected by AKIN and KeGFRbased methods. This is likely due to the lack of time-dependent criteria in the Delta check method and the fixed RCV (17% in this study), which will overdiagnose AKI when the initial Cr is in the normal range [12,19].…”