Quantitative Validation Overview

SMILE

Johns Hopkins University

Baltimore, MD USA

SMILE AMR and CRR Requirements-Hematology

SMILE Hematology AMR and CRR Verification Guidelines

The ANALYTICAL MEASUREMENT RANGE (AMR) is the range of analyte values that a method can directly measure on the specimen without any dilution, concentration, or other pretreatment not part of the usual assay process. AMR validation is the process of confirming that the assay system will correctly recover the concentration or activity of the analyte over the AMR. The manufacturer defines the AMR. It is the laboratory’s responsibility to verify it.

The CLINICAL REPORTABLE RANGE (CRR) is the range of analyte values that a method can report as a quantitative result, allowing for specimen dilution, concentration or other pretreatment used to extend the direct AMR. The laboratory should establish a CRR that covers a range inclusive of Grade 4 Adverse Events on the DAIDS Toxicity Table without exceeding the manufacturer’s recommendations for dilution.

It is only necessary to verify the reportable range for measured analytes only. Consult the instrument user’s manual to determine which analytes are measured and which are calculated. Generally the measured analytes will be White Blood Count, Red Blood Count, Hemoglobin, Platelets and MCV (on some analyzers).

I.  Analytical Measurement Range (AMR)

A.  Sample Criteria

1.  Quality control, calibrators or commercial linearity standards should be used.

2.  It may be necessary to dilute the lowest sample to verify the low end of Analytical Measurement Range (AMR).

3.  The high end of the AMR will only be as high as the highest sample.

B.  Testing

1.  At a minimum, run each sample in duplicate and average the results.

2.  Data should be evaluated immediately to identify and correct any problems.

C.  Evaluation of data:

1.  AMR

a.  The reportable range must be within the manufacturer’s AMR.

b.  Refer to Appendix 1 for Total Allowable Error (TEa) limits.

c.  Upper Limit Verification - The manufacturer’s upper limit can be accepted if the known sample is within the percent TEa of your AMR upper limit.

i.  Your measured value must also be within TEa of the known sample.

ii.  Upper Limit Example:

iii.  Measured values needed:

iv.  If TEa is 15%, an upper AMR of 25 can be verified with a known sample of 21.25 – 28.75 if the measured sample is within TEa of the known sample. In the example above, the measured value must be between 20.4 – 27.6.

v.  If a sample within TEa cannot be obtained, the highest known sample measured and within TEa should be used as the highest reportable undiluted value.

i.  For Example:

ii. New upper AMR = 10.5 mg/dL

d.  Lower Limit Verification - The manufacturer’s lower limit can be accepted if the known sample is within the minimum detectable difference or percent TEa of the lower limit (whichever is greater).

i.  Your measured value must also be within TEa of the known sample.

ii.  Lower Limit Example:

iii.  Measured values needed:

iv.  If TEa is 0.12, a lower AMR of 0.5 can be verified with a known sample of 0.38 to 0.62 if the measured sample is within the minimum detectable difference or TEa, whichever is greater. In the example above the measured value must be between 0.48-0.72).

v.  For analytes that round to the nearest whole number, a proximity limit of 1 is acceptable to verify the lower range of 0.

vi.  Serial dilution should be used to obtain a sample within the desired range. However, if a sample within TEa cannot be obtained, the lowest known sample measured and within the acceptable TEa will be used as the lowest reportable range.

i.  For Example:

ii. New lower AMR = 0.7 x109 cells/uL

2.  CRR

a.  The Clinical Reportable Range (CRR) must extend the AMR in order to include grade 4 events of the Division of AIDS Toxicity Table.

b.  The lab should establish what dilutions are necessary to cover this range, bearing in mind that a minimum amount of dilution is ideal since accuracy decreases with increasing dilution.

c.  The laboratory should decide the maximum value of dilution that will be allowed without exceeding the manufacturer’s recommendations for dilution.

d.  Any samples that do not give a numerical value beyond this allowed dilution should be reported as greater than the upper end of the CRR.

II.  References

A.  GCLP Workshop and Workbook18-20 May 2008, Verification of Performance Specifications, pages 1-33.

B.  Clinical and Laboratory Standards Institute (CLSI). Evaluation of the Linearity of Quantitative Measurement Approved Guideline-Second Edition, CLSI document EP6-A (ISBN 1-56238-498-8) Clinical and Laboratory Standards Institutes, 940 West Valley Road, Suite 100, Wayne, Pennsylvania 19098-1898 USA, 2005.

C.  EP Evaluator Release 8, David G. Rhoads Associates Inc., www.dgrhoads.com.

D.  James O. Westgard, Online Validation Training, Westgard QC, Inc. www.westgard.com, Sections 9-Determining Reportable Range.

SMILE AMR and CRR Requirements-Hematology v.1.0.doc Page 5 of 5 11 August 2010