Ann Lab Med.  2018 Sep;38(5):420-424. 10.3343/alm.2018.38.5.420.

Proposed Imprecision Quality Goals for Urinary Albumin/Creatinine Ratio

• Ko DH
• Lee SW
• Hyun J
• Kim HS
• Park MJ
• Shin DH

• KMID: 2434730
• DOI: http://doi.org/10.3343/alm.2018.38.5.420

Abstract

BACKGROUND
The urinary albumin/creatinine ratio (ACR) is an important indicator of albuminuria. We aimed to estimate ACR uncertainty and its impact on test results and proposed imprecision quality goals based on the estimated uncertainty.
METHODS
The combined ACR uncertainty was calculated using the individual uncertainties of urinary albumin and creatinine. ACR confidence intervals (CIs) were estimated based on the expanded uncertainty. When the CI contained the ACR category boundary (30 or 300 mg/g), the cases were considered ambiguous. Quality goals for ACR were suggested using the number of ambiguous cases among actual patient results.
RESULTS
The number of ambiguous cases resulting from the combined ACR uncertainty was higher than expected based on biological variation (BV) quality goals. When the ACR met BV quality specifications, we estimated that 4.8-15.5% of the results may have been misclassified. To minimize the number of ambiguous results, the minimum, desirable, and optimum quality goals were set at 34.0%, 18.0%, and 4.5%, respectively.
CONCLUSIONS
We expressed ACR uncertainty using the uncertainties of urinary albumin and creatinine and assessed the impact of this combined uncertainty on the test results. Subsequently, we proposed imprecision quality goals for ACR based on ambiguous results.

Keyword

Albumin/creatinine ratio; Uncertainty; Reclassification; Quality goal

MeSH Terms

Albuminuria
Creatinine
Humans
Uncertainty
Creatinine

Figure

• 

  Fig. 1 Histogram of urinary albumin/creatinine ratio (ACR) results in category A2 (30–300 mg/g of ACR). It showed a skewed distribution towards lower values.

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