PEPFAR Quality Control and Method Validation Activity 8 Job Aid 2: Sample TEA Calculations

Job Aid 2: Sample TEA Calculations 814 Sample Calculations to Determine your TEA Limits When TEA is provided in percent(%) Using peer group's median %CV x 3 (PT Test Results) Effective Date: 12/6/2016 HILS1746 Using the Target Value (in units), multiply the value by the % TEA to convert into units. While ignoring the sample concentrations, list your PT peer TEA in units = (TEA %/100%)* Target Value group's %CV in increasing order Lower TEA Limits = Target Value - TEA in units Select the median %CV Upper TEA Limits = Target Value + TEA in units . To calculate % TEA, multiply the median %CV by 3 ( % TEA = median %CV * 3) For example, a QC control for glucose with a target value of 5.6 . Follow When TEA is provided in percent(%) instructions to mmol/L, the acceptable performance for glucose is 6.9% using the TEA determine your lower and upper TEA limits. from the desirable biological variation. For example, using results from a PT survey as follows: TEA in units = (6.9%/100%)* 5.6mmol/L = 0.4 mmol/L Sample Mean SD %CV Lower TEA Limits = 5.6 mmol/L - 0.4 mmol/L = 5.2 mmol/L C-3 1.2 0.08 6.7% Upper TEA Limits = 5.6 mmol/L + 0.4 mmol/L = 6.0 mmol/L C-5 4.2 0 .. 33 7.9% C-2 1.0 0.08 8.0% When TEA is provided in units (e.g. CLIA) median For example, a QC control for glucose with a target value of 2.2 C-1 0.6 0.05 8.3% mmol/L, CLIA's acceptable performance for glucose is Target Value + C-4 3.0 0.26 8.7% 0.3mmol/L or 10% whichever value is greater. % TEA =8.0% * 3 = 24% TEA in units = 0.3 mmol/L Lower TEA Limits = 2.2 mmol/L - 0.3 mmol/L = 1.9 mmol/L Upper TEA Limits = 2.2 mmol/L + 0.3 mmol/L = 2.5 mmol/L Applying Tonk's Rule [(reference range span)/4/mean of range]* 100% In this example, the concentration limits of 0.3 mmol/L are greater than the percentage value limits of 10%. (10% of 2.2 is 0.2 For example, the CD4 count reference range is 500 mmol/L). Therefore, for this QC control, the concentration acceptable cells/mm3 to 1000 cells/mm3 performance would be applied. % TEA = [(1000 - 500)/4/750]*100% = 16.7% When TEA is provided in + 3SD Using a survey sample report, select a concentration close to the True Value of your control material. Multiply the SD by 3. 78