“Quality Control” in Hematology

1. “Quality Control” in Hematology June 14, 2013 M R Tiwari M.Sc-TQM

2. Laboratory test results (Good laboratory practice, GLP) Clinical diagnosis Patient management

3. Good Laboratory Practice Quality can be assured at • Pre-analytical stage • Analytical stage • Post-analytical stage

4. Quality Management of the Analytic Phase

5. Terminologies = QC at Analytical stage

6. PRECISION (REPRODUCIBILITY) • Definition Precision refers to the reproducibility of a result. • Comparing QC terms to a targetFigure illustrates that the results are precise (close together) but not accurate (they are not in the bull’s-eye). • Checking precision is required while -calibration -troubleshooting QC at Analytical stage

7. ACCURACY • Definition Closeness of a result to the true (accepted) value. NOTE: Before determining accuracy, first determine precision. • Comparing QC terms to a targetFigure illustrates that the results are accurate (in the bull’s-eye) and precise (close together). NOTE • You cannot have accuracy without precision. • However, you can have precision without accuracy. QC at Analytical stage

8. NEITHER ACCURACY NOT PRECISION • This figure illustrates that the results are neither accurate nor precise. • None of the results are close together, and none of them are in the bull’s-eye. QC at Analytical stage

9. Statistics involved… • Mean • Standard deviation (SD) • ± 1SD • ± 2SD • ± 3SD • Coefficient of variation (%CV) QC at Analytical stage

10. Hematology analyzers QC at Analytical stage

11. Technical Specifications QC at Analytical stage

12. Performance specification (Linearity) QC at Analytical stage

13. Precision QC at Analytical stage

14. Test selectivity / Throughputs QC at Analytical stage

15. Sample Modes / Volumes QC at Analytical stage

16. Calibration (setting accuracy) Hematology analyzer

17. Setting accuracy Calibration Is done to standardize the instrument for accuracy. Calibrator Certified Reference Material (CRM) used to calibrate a measurement on an analyzer. Cal-Factors If any deviation from calibration references is observed necessary calibration correction factors are applied to set the accuracy of the instrument. QC at Analytical stage

18. Calibration • Pre-calibration check • Total maintenance of the instrument • Reagents (replenish or replace) • Calibrator (Check for expiry) • Calibration procedure • Precision check • Carryover check • Calibration in both (open and closed modes) • Post-calibration validation • Run calibrator as samples • Run 3 level controls QC at Analytical stage

19. CARRYOVER • Carryover is defined as a number of cells remaining behind following the cycling of a blood sample. • This test is performed to determine if one sample interferes with the accurate analysis of the next sample. • Ideally, carryover shall be very low. • Measure a specimen with a high concentration in triplicate, immediately followed by a specimen with a low concentration in triplicate. • Where l1 and l3 are the results of the first and third measurements of the samples with a low concentration and h3 is the third measurement of the sample with a high concentration. QC at Analytical stage

20. Daily internal quality control (IQC) Hematology analyzers

21. Daily IQC in hematology analyzers • Commercial controls • Retained sample • Moving averages (Bull’s algorithm) QC at Analytical stage

22. DAILY IQC of Hematology analyzer QC at Analytical stage

23. In 1931, Dr. Walter Shewhart, a scientist at the Bell Telephone Laboratories, proposed applying statistical based control charts to interpret industrial manufacturing processes. In 1950, S. Levey& E.R. Jennings suggested the use in the clinical laboratory. Control Chart's Inventor QC at Analytical stage

24. Establishing Laboratory’s acceptable ranges for controls Reference : CELL-DYN Sapphire Operator’s Manual, 11-16 Establishing laboratory control mean Commercial controls • New lot of control material should be analyzed in parallel with current lot. • This may be accomplished by running the new controls twice a day for five days (we run three times for three days and one time on fourth day). • The mean of the ten runs is then used. • A control file is set up for the new mean. • The same file is used to run control for the reminder dating of period. QC at Analytical stage

25. Establishing Laboratory’s acceptable ranges for controls Reference : CELL-DYN Sapphire Operator’s Manual, 11-16 Establishing laboratory acceptable ranges (SD) Commercial controls • The expected ranges published by the manufacturers do not represent standard deviations and are generally too broad for effective quality control. • These ranges are determined by evaluating three to six months of data (data from the previous IQC) for a particular level of control. • The individual SD values may be averaged as follows: N = number of values in a group SD = Standard Deviation of the values in that group i = the last group of values The resultant long-term instrument SD and the laboratory established mean is used to monitor instrument performance QC at Analytical stage

26. L-J chart Interpretation Dr. James O Westgard QC at Analytical stage

27. Modification of 10x Dr. James O Westgard QC at Analytical stage

28. × I prefer the ‘xyz’ analyzer because its 2SD QC charts are amazingly flat 2SD QC at Analytical stage

29. Retained sample testing • A previous days (retained) sample, stored at 2-80C, with normal counts is run as 1st sample after the controls are analyzed. This is done on a daily basis. • This sample is considered as the precision sample. • This sample is then analyzed every one hour or / after 30 patient samples and also as the last sample before the analyzer is shut down. • The mean, SD and CV is monitored. QC at Analytical stage

30. When a control point is outlier… Warning rule = use other rules to inspect the control points Rejection rule = “out of control” • Stop testing • Identify and correct problem • Repeat testing on patient samples and controls • Do not report patient results until problem is solved and controls indicate proper performance QC at Analytical stage

31. Other additive IQCs QC at Analytical stage

32. Flags & correlation with PBS QC at Analytical stage

33. PBS examination • Ensure good drying of the smear • Do not use overused stains • Maintain required pH of the buffer • Maintain the staining time A good smear Quality tips QC at Analytical stage

34. Flag 1 • ? Suspect BLASTS • ? Monocytosis PBS correlation Analyzer PBS : Monocytes / Blasts QC at Analytical stage

35. Flag 2 • ? Suspect BLASTS • ? Lymphocytosis • ? Variant lymphocytes PBS correlation Analyzer PBS : Lymphocytes / Blasts QC at Analytical stage

36. Flag 3 • ? Platelet clumps • Thrombocytopenia PBS correlation Analyzer PBS : Platelet clumps / QC at Analytical stage

37. Flag 5 • ? Giant Platelets • Thrombocytopenia PBS correlation Analyzer PBS : Giant platelets QC at Analytical stage

38. External Quality Assessment(Proficiency testing) QC at Analytical stage

39. Normal Distribution Curve or Gaussian curve Describes events or data that occur symmetrically about the mean. Out of 100 events 68.7 will fall within ±1 SD 95.4 will fall within ± 2 SD 99.7 will fall within ±3 SD QC at Analytical stage

40. Comparative performance evaluation Z-Score QC at Analytical stage

41. If EQAS/PT is not available QC at Analytical stage

42. If EQAS results are out QC at Analytical stage

43. Summary… Laboratory test results • Pre-analytical stage • Analytical stage • Post-analytical stage Clinical diagnosis Patient management Quality Good Laboratory Practice Thank you…