APPLICATION OF  THE MONTH EXAMPLE PLANNING APPLICATIONS USING EUROPEAN BIOLOGIC GOALS: Cholesterol and glucose 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.  Go back to the cholesterol application  Glucose:  1. Define the Quality Requirement 2. Evaluate the analytical factors 3. Enter parameters in computer program 4. Obtain OPSpecs chart 5. Assess probabilities of rejection 6. Select the control rules and numbers of control measurements, N 7. Adopt a Total QC Strategy 8. Reassess for changes in performance References

Note: this section of the WQC homepage is dedicated to presenting example QC applications and illustrations of WQC planning process. Every month, a new example demonstrates the use of power function graphs, critical-error graphs, OPSpecs®charts, and other graphic planning tools. If you wish to submit your laboratory data for free evaluation, please contact us by phone, fax or e-mail. If WQC chooses your data, the assessment will be displayed online in this space!

Glucose application

1. Define the Quality Requirement

2. Evaluate the analytical factors

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.

4. Obtain OPSpecs chart

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.

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

7. Adopt a Total QC Strategy

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

For the clinical quality requirement considered earlier in the glucose POC application, this method could actually be controlled using x_0.01/R_0.01 rules, the 1_2.5s single rule, or the 1_3s/2_2s/R_4s 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.

Return to the cholesterol application

References

• 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

Past QC Applications:

• Potassium - November 1996
• Cholesterol for analytical requirement using OPSpecs charts - December 1996
• Immunoassay QC with higher N multirules - January 1997
• QC selection for a multitest Chemistry Analyzer - February 1997
• Cholesterol for clinical requirement using OPSpecs charts - March 1997
• QC for a POC Glucose Test - April 1997
• Establishing QC Acceptability Criteria for CLIA - May 1997