QUALITY control in hematology by Dr yogeeta Tanty.pptx

Quality control of the automated analysers used in hematology.

1. QUALITY CONTROL IN HEMATOLOGY Dr Yogeeta Tanty

2. What is Quality? A measure of excellence . A state of being free from defects, deficiencies, and significant variations . Brought about by strict and consistent adherence to measurable and verifiable standards.

3. Quality assurance Quality assurance(QA) in a laboratory is intended to ensure reliability of the laboratory tests . A QA program should include standardization of tests and of instruments in order to achieve acceptable levels of precision and accuracy.

4. QUALITY CONTROL Quality control (QC) is a procedure designed to detect, reduce and correct deficiencies in the lab’s internal analytical process. It should be done prior to the release of patient results and to improve the quality of the results reported by the laboratory.

5. Important aspects of QC in hematology are- Calibration of automated instruments. Monitoring of accuracy and precision of instruments and procedures. Verifying the reliability of test results.

6. Calibration It is a primary process to standardize the instrument for accuracy. It is done to compare the measurement values delivered by a device with those of calibration standard of known accuracy. According to NABL 112 , all instruments should be calibrated according to maufacturer’s guidelines atleast once a year.. And periodic calibration verification should be carried out after preventive maintenance.

7. Pre analytical Post analytical A nalytical Quality control

8. PRE-ANALYTICAL   Factors that affect the lab results due to handling of specimen sample prior to analysis. Misidentification of patient Mislabeling of specimen Fasting state Alcohol consumption Dehydration

9. Prolonged use of tourniquet K2 EDTA causes less cellular damage and is recommended by The International Council For Standardisation In Hematology (ICSH). Improper techniques like squeezing can cause microclots or platelet clumps. Smear preparation Ensuring proper drying of the smear

10. Quality control in analytical phase INTERNAL QC EXTERNAL QC Process that monitors accuracy It compares one’s lab results to and reproducibility of test results other labs. through the use of controls. Serves to evaluate internal It is helpful for making immediate QC. decisions. Maintains long term accuracy Ensures the lab is performing to external standards.

11. Accuracy: Reflects how close a measurement is to the correct or accepted value. Precision : (reproducibility) is the closeness of values when a test is repeated a number of times.

12. INTERNAL OR INTRA-LABORATORY quality CONTROL Internal assessment of Analytical quality by regular measurement of known/ assigned value samples. Analysis of control samples is done daily using multilevel controls i.e Low , normal and high level or using normal and abnormal samples .  

13. Hematology analyser – sysmex XN -1000

14. XN CHECK is used as control blood for the quality control of Sysmex X series instrument system. It includes stabilized human RBCs, human WBCs , platelet and nucleated red blood cell component in a preservative medium. Once opened ,shelf life is 7 days. Storage – 2 -8 º C It provides parameters – Complete blood count White blood cell differentials Reticulocyte Nucleated RBCs

15. Coagulation analyser -DESTINY PLUS

16. Control 2 is a lyophilized human plasma in which factors 2,7,9, and 10 have been selectively and partially removed to get abnormal control in coagulation.

17. Statistical Methods for Assessment Mean ( Target Value) Standard deviation (SD) Coefficient of Variation (CV) Levey Jennings chart Westgard rules Z Score

18. Standard deviation It is an absolute measure of dispersion. It measures how far a data point lies from its mean . It is calculated for a single data set.

19. For example, sample – 2,3,4,5,6 Mean = 2+3+4+5+6 =20/5 = 4 5 2-4=2 4 4+1+0+1+4=10 =√10/4 3-4=-1 1 5-1=4 4-4=0 0 SD = 1.58 ~1.5 5-4=1 1 6-4=2 4

20. 4+1SD 4+1X1.5= 5.5 4-1SD 4 -1X 1.5= 2.5 4+2SD 4+2X1.5 = 4+3= 7 4- 2SD 4- 2X1.5= 4-3=1

21. 1 2.5 4 5.5 7

22. LEVEY JENNINGS CHARTS These are statistics based control charts to monitor quality control. The control values are plotted on Y axis. The days of the month are plotted on X axis.

23. Westgard Rules Westgard Rules are multiple QC rules to help analyze whether or not an analytical run is in-control or out-of-control.

24. Six commonly used westgard rules 1 2s One control measurement exceeding 2 standard deviations of control limits either above or below the mean. This rule is used a warning rule to trigger careful inspection of the control data.

25. 1 3s A run is rejected when a single control measurement exceeds the mean + 3 control limits.

26. 2 2s The control run is rejected with 2 consecutive control measurements ,2 standard deviations on the same side of mean with this rule.

27. R 4s This rule rejects a run if two control measurements in a group exceed the mean with a 4 standard deviation difference between the 2 controls.

28. 4 1s This rule rejects a run with the 4th consecutive control measurement exceeding 1 standard deviation on the same side of the mean.

29. 10 x This rule rejects a control run when there are 10 consecutive controls on the same side of the mean.

30. Errors on l- j charts Systematic errors Random errors Shifts Trends D ispersion

31. Systematic errorS Errors that detect every test in a constant, predictable manner. For example – change in reagent lot number improper reagent preparation Incorrect storage conditions

32. Random errors Sudden control value of more than 2 SD among acceptable control values. May occur 1 in every 20 analyses Precision is affected Causes –Temperature variation Bubbles in reagent Pipetting error Operator error

33. RANDOM ERROR

34. SHIFT Abrupt change in control values. Sudden fall on one side of the mean. Causes- Outdated controls and reagents Wrong controls,

35. trend Change that occurs slowly over time. Progressive drifting from the mean. Causes- deteriorating agents.

36. dispersion Random control results. Wide scattering of values. Causes- Systemic failure Operator error

37. Hematology analyser cleaning agent

38. According to NABL 112 , alternate methods of quality control procedures are- Review of daily mean Delta check Clinical correlation Correlation with other laboratories ( Exchange of samples with other accredited laboratories with one functioning as reference laboratory.)

39. Storage of examined specimens according to NABL 112 The examined specimens can be stored for re-examination for period and temperature as specified below Complete Blood Counts: <24 hours at 2-80C Coagulation test: <4 hours at room temperature The storage requirements for the samples which are retained for longer period are as follows: i ) Plasma can be stored at or below -20ºC for 1 week and -80ºC for up to 1 year. ii) For PT up to 24 hours if samples are maintained between 18 - 24ºC and for heparin monitoring it shall be within an hour. Bone Marrow aspiration slides: 5 years Bone Marrow biopsy: 10 years

40. EXTERNAL OR INTER-LABORATORY quality CONTROL External quality assessment scheme (EQAS) or Proficiency Test. Its based on analysis of control samples periodically by an outside agency in order to compare accuracy levels of different laboratories . Labs using the same reagents (peer group) are compared and performance is reported in terms of Deviation index or Z Score.   EQAS complements internal quality control and is a basic requirement for laboratory certification and accreditation.

41. Quality control samples Quality control samples obtained from the manufacturer are usually manipulated to lengthen the shelf life. Therefore, direct comparison with patient results is not possible. Moreover, EQAS material should not be used for calibration purposes. There should be at least two specimens for every test.

42. Proficiency test items The programme must ensure that the items are: stable , safe and according to all relevant national safety standards. negative for infectious agents (e.g. hepatitis B and C, HIV in the case of human blood products)

43. Agents such as antibiotics and antifungals or preservative (sodium azide ) can be used in some specimens to reduce contamination. Vials should be leak-proof and made of material usually plastic or glass, so that it does not react .

44. Those to whom delivery is expected to take longest, should receive two or more panels . To return one panel unopened to the organizing centre is requested . They then test the panel again to ensure that the specimens have remained stable in twice the normal period of transport.

45. Homogeneity TEST Prior to preparation for distribution, specimens should be tested to demonstrate they have a consistent value within the tolerance limits . And If specimens can be analysed in a manner that will not destroy them during testing.

46. Z score Z Score or standard score indicates how much a given value differs from the standard deviation. It is the number of standard deviations a given value is from the mean . Z = x-µ , where Z = standard or Z score δ x= observed value µ= mean of the sample δ = standard deviation

47. Z score 0: It happens rarely even with the most competent lab . Z score between -2 to +2 : is designated ‘ acceptable ’ or ‘ satisfactory ’. Z score outside range -3 to +3 regarded as ‘ unsatisfactory ’ or ‘ not acceptable ’. Z score between -2 to -3 and +2 to +3 of isolated event are regarded as ‘ questionable ’. These criteria are stated in ISO/IEC standard 17043:2010

48. ISHTM-AIIMS-EQAP External quality control Programme is organized by the Department of Hematology, AIIMS New Delhi and Indian Society of Hematology & Transfusion Medicine (ISHTM). It is accredited by NABL (National accreditation board for testing and calibration laboratories.)

49. Youden ( xy ) plot Two samples analysed and the results sample A plotted on x axis and B on y axis.  Lines then drawn demarcating the SD (or 2SD). The results in the central block are satisfactory. Results in top R  (B) and bottom L blocks (A) indicate consistent over or under readings .  Results elsewhere indicate random errors.

50. Response to EQA reports NABL 112 provides a simple approach – Clerical error – transcription error ( pre or post analytical) Methodological problem Instrument function checks ( e.g.,temperatures ) Incorrect instrument calibration. Carry-over from previous specimen. QC material not run within expiration date Technical problem Sample not placed in proper order on instrument.

51. Problem with proficiency testing materials Matrix effects: The performance of some instrument may be affected by the matrix of the PT sample. This can be overcome by assessing participants in peer groups – to be done by the PT provider. Problem with evaluation of results by the PT provider Incorrect data entry by PT provider. No explanation after investigation – can be considered random error.