Tools, Technologies and Training for Healthcare Laboratories

Glucose, European Biologic Goal

This example shows how to perform QC Design for a glucose method, using European biologic goals.

Example QC Planning Application using European Biologic Goals:

Recommendations on how to use the QC Validator program with the European biologic goals for imprecision and inaccuracy have been published, along with some example applications [1]. Two additional applications are illustrated here to facilitate comparisons between the European biologic goals, the CLIA analytical quality requirements for total error, and the clinical quality requirements for medically important changes.

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Glucose application

1. Define the Quality Requirement

For glucose, the EGE-Lab specifications are 1.9 % for bias (interim 4.4%) and 2.2 % for imprecision. The total error calculated using the interim bias specification is 8.0% (1.65*2.2 % + 4.4% = 8.0 %).

2. Evaluate the analytical factors

Given a POC method that has stable performance of smeas=2.44% and biasmeas=2.7%(such as discussed earlier in the QC planning application for a point-of-care glucose test). The stable imprecision is a little bit too large, but the stable inaccuracy is well with the interim specification.

3. Enter parameters in computer program

The input parameters for the QC Validator program are shown here. A decision level of 90 mg/dL corresponds to 5.0 mmol/L, which is used here to be consistent with the earlier example that used a clinical quality requirement. qcap9f4

4. Obtain OPSpecs chart

Candidate control procedures are selected by pressing the "From Table" button and choosing individual control rules and N's from the long list included in the program. For European labs, mean/range rules are of interest and are included in the list chosen.

5. Assess probabilities of rejection

The stable imprecision itself is not acceptable, but the stable bias is less than the interim goal. When the calculated total error is used to assess QC design, the OPSpecs chart for TEa of 8% and 90% AQA shows the difficulty of assuring the quality required by the European biologic goals. The operating point (that represents smeas of 2.44% as the x-coordinate and biasmeas of 2.7% as the y-coordinate) is far to the right of the allowable limits of imprecision and inaccuracy for the candidate QC procedures with Ns of 2. qcap9f5

6. Select the control rules and numbers of control measurements, N

For the glucose method is not possible to assure the quality required by European biologic goals.

7. Adopt a Total QC Strategy

tqchartIn a situation like this, one must stress the non-statistical elements of QC, such as preventive maintenance, instrument function tests, and personnel training. You should use a low TQC strategy that emphasizes non-statistical components.

In this table, the relative number of x's indicate the relative emphasis on the different components in a Total QC strategy. SQC stands for Statistical QC. QI stands for Quality Improvement. Other QC includes preventive maintenance, instrument function checks, performance verification tests, and patient data QC algorithms.

8. Reassess for changes in performance

Even if bias were reduced to zero, the imprecision would be too great; a method CV of 1.8% or better is needed to assure the desired quality will be achieved in routine testing (as shown by the x-intercepts of the OPSpecs lines for the candidate QC procedures). By comparison, the US CLIA analytical quality requirement is 10% and would require a method imprecision of 2.3% or better for these same N=2 QC procedures.


For the clinical quality requirement considered earlier in the glucose POC application, this method could actually be controlled using x0.01/R0.01 rules, the 12.5s single rule, or the 13s/22s/R4s multirules with Ns of 2; a method with a CV as large as 3.6% could be tolerated if bias were zero.

For further discussions and comparisons of the European biologic goals, the CLIA allowable total errors, and clinical quality requirements, see references 2-4.

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  1. Hyltoft Petersen P, Ricos C, Stockl D, Libeer J-C, Baadenhuijsen H, Fraser CG, Thienpont L. Proposed guidelines for the internal quality control of analytical results in the medical laboratory. Eur J Clin Chem Clin Biochem 1996;34:983-989.
  2. Westgard JO, Seehafer JJ, Barry PL. European specifications for imprecision and inaccuracy compared with operating specifications that assure the quality required by US CLIA proficiency-testing criteria. Clin Chem 1994;40:1228-1232.
  3. Westgard JO, Seehafer JJ, Barry PL. Allowable imprecision for laboratory tests based on clinical and analytical test outcome criteria. Clin Chem 1994;40:1909-1914.
  4. Hyltoft Petersen P, Fraser CG. Setting quality standards in clinical chemistry: Can competing models based on analytical, biological, and clinical outcomes be harmonized? Clin Chem 1994;40:1865-1868.Page references for CLIA QC requirements