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Kidney Week

Abstract: SA-PO402

Impact of Inter-Laboratory Variability of Serum Creatinine Assays on KFRE Risk Scores

Session Information

Category: Chronic Kidney Disease (Non-Dialysis)

  • 302 CKD: Estimating Equations, Incidence, Prevalence, Special Populations

Authors

  • Jalan, Divyanshi, Queen's University School of Medicine, Kingston, Ontario, Canada
  • Lee, Elizabeth S., University of British Columbia, Vancouver, British Columbia, Canada
  • Collier, Christine P., Queen's University, Kingston, Ontario, Canada
  • Akbari, Ayub, University of Ottawa, Ottawa, Ontario, Canada
  • White, Christine A., Queen's University, Kingston, Ontario, Canada
Background

Inter-laboratory variation in creatinine (Cr) measurement exist and result in inter-laboratory variability in eGFR-EPI and chronic kidney disease (CKD) diagnosis. We aim to examine the impact of inter-laboratory variability in Cr measurement on the Kidney Function Risk Equation (KFRE).

Methods

Split serum samples from 33 patients with eGFR-EPI between 10 and 60 ml/min/1.73m2 were sent to 12 laboratories for Cr measurement. For each patient and laboratory we calculated the 5 year risk of ESKD using the KFRE equation (KFRE-5) assuming 65 year old non-African American woman and three ACR levels (27, 266, 885 mg/g). For each patient and ACR value we calculated the KFRE-5 all method mean (AMM), coefficient of variation (CVa) and range. For the cohort, we determined the mean KFRE-5 range, CVa and the mean ratio of minimum and maximum KFRE-5 scores.

Results

Figure 1 shows individual patients’ mean, minimum and maximum KFRE-5 scores (ACR 266 mg/g). There is substantial variability in KFRE scores which are more pronounced with higher albuminuria and when KFRE values are between 5% and 80% [Table 1, Figure 1].

Conclusion

Inter-laboratory variability of serum Cr measurement results in variability in KFRE scores which is more pronounced when eGFR is moderately-severely reduced and ACR is high. This needs to be considered when using KFRE cut-offs for referrals, clinic discharge, vascular access placement and suitability for CKD funding. Manufacturers need to improve assay specificity in order to reduce KFRE variability between laboratories.

Table 1: Mean ± SD KFRE-5 range and max/min ratios
 ACR 27 mg/gACR 266 mg/gACR 885 mg/g
KFRE-5 range (mean ± SD) (%)2.9 ± 2.46.3 ± 4.58.4 ± 5.7
KFRE-5 CVa (mean ± SD) (%)20.8 ± 11.319.9 ± 11.619.0 ± 12.0
KFRE-5 max/min
(mean ± SD)
2.4 ± 1.22.3 ± 1.22.3 ± 1.2

Figure 1: Individual patients’ mean, minimum and maximum KFRE-5 scores (ACR 266 mg/g)

Funding

  • Private Foundation Support