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PEPFAR Quality Control and Method Validation Activity 14 Handout: Precision

This PDF contains supportive documents for Activity 14.

177 Precision Handout 14B02 Chemistry Precision Guidelines PRECISION is reproducibility -- the agreement of the measurements of replicate runs of the same sample. Replication experiments are performed to estimate the imprecision or random error of a given analytical method. I. Short -Term (Within-run/Day) A. Sample: 1. Two levels (Low / High or Normal / Abnormal) 2. Patient or quality control 3. Select values near the medical decision point(s) of interest for the analyte B. Testing: 1. Ensure there is a sufficient reagent to perform all 20 tests. 2. Run each sample 20 times on the same run, if possible, or least within the same day. C. Acceptability criteria: 1. Calculate the coefficient of variation (CV) for each level using 20 data points. 2. Compare the calculated CV to the ma nufacturer's stated precision claims found in the package insert. 3. If manufacturer's precision cannot be met, it is acceptable to attain precision that is <25% of the CLIA Allowable Error. 4. If Short -Term precision is unacceptable, consult the instrument 'S manufacturer for technical assistance. 5. If unable to resolve issues with short-term precision, the method validation process should be discontinued and a new method selected for potential implementation. II. Long-Term (Between-run/Between Day) A. Sample: 1. Two levels (Low/High or Normal/Abnormal) 2. Patient or control serum. A lab may already have this data available from their daily QC runs. 3. Select values near the medical decision point(s) of interest for the analyte B. Testing: Run each sample 1 time per day for 20 days for a minimum of 20 total data points for each level of material used. C. Acceptability criteria: 1. Calculate the CV for each level using 20 data points 2. Compare to manufacturer's stated precision claims found in the package insert. 3. If manufacturer's precision cannot be met, it i s acceptable to attain precision that is <33% of the CLIA Allowable Error 4. If Long-Term precision is unacceptable, consult the instrument 'S manufacturer for technical assistance. Modified from pSMILE.org website. Equ35-A-03_Prec_Rqmt_Chem. Last accessed May 3, 2013 Page 1 of 2 HILS1746 Effective Date: 12/6/2016 178 Precision Handout 14B02 III. References A. GCLP Workshop and Workbook18-20 May 2008, page 16 B. Clinical and Laboratory Standards Institute (CLSI). User Verification of Performance for Precision and Trueness: Approved Guideline-Second Edition. CLSI document EP15-A2 (ISBN 1-56238-574-7). Clinical and Laboratory Standards Institutes, 940 West Valley Road, Suite 100, Wayne, Pennsylvania 19098-1898 USA, 2005. C. NCCLS. (Currently CLSI) Evaluation of Precision Performance of Quantitative Measurement Methods; Approved Guideline Second Edition. NCCLS document EP5-A2 (ISBN 1-56238-542-9). NCCLS, 940 West Valley Road, Suite 1400, Wayne, Pennsylvania 19087-1898 USA, 2004. D. Westgard, James O. (2003). Basic Method Validation (2nd ed.). Madison: Westgard QC, Inc. E. Westgard, James O. (2008). Basic Method Validation (3rd ed.). Madison: Westgard QC, Inc. Modified from pSMILE.org website. Equ35-A-03_Prec_Rqmt_Chem. Last accessed May 3, 2013 Page 2 of 2 HILS1746 Effective Date: 12/6/2016