Quality control lecture CPath master 2014 Ain Shams


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Basics of quality management or assurance program detailing values of internal quality control material analysis and interpretation and external quality control or proficiency testing programs in medical laboratories

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Quality control lecture CPath master 2014 Ain Shams

  1. 1.  All management systems are focused on getting the job done.  More efficient and effective management guarantees the job to be done in the proper way. Larger profit Better serviceVs
  2. 2. STAGE ACTIVITIES PERFORMED 1. TOTAL QUALITY MANAGEMENT Management approach centered around “Customer Satisfaction” 2. QUALITY MANAGEMENT All of the below plus the economic aspects of “Cost of Quality” 3. QUALITY SYSTEM “Comprehensive and Coordinated” efforts to meet quality objectives 4. QUALITY ASSURANCE Systematic activities to provide “Confidence” that the organization meets requirements for quality 5. QUALITY CONTROL Operational techniques applied to “Specific Tasks” for quality and regulatory compliance.
  3. 3.  Quality : degree to which a set of inherent characteristics fulfills requirements  Quality control: part of quality management focused on fulfilling quality requirements  Quality assurance: part of quality management focused on providing confidence that quality requirements will be fulfilled  Quality management: coordinated activities to direct and control an organization with regard to quality
  4. 4. 1942-521942-52 US Military develop requirements for contractors for shell, aircraft, missileUS Military develop requirements for contractors for shell, aircraft, missile supplierssuppliers (Quality without 100% inspection)(Quality without 100% inspection) 19471947 International Organization for Standardization (ISO)International Organization for Standardization (ISO) created to adopt industrialcreated to adopt industrial standardsstandards 19591959 US Department of Defense establishedUS Department of Defense established MIL-Q-9858MIL-Q-9858 quality managementquality management 19631963 MIL-Q-9858 is internationalized as anMIL-Q-9858 is internationalized as an ABCAABCA standardstandard 19681968 NATO adopts MIL-Q-9858A as Allied Quality Assurance Publication 1 (NATO adopts MIL-Q-9858A as Allied Quality Assurance Publication 1 (AQAP-1AQAP-1)) 19791979 British Standards Institute (BSI) developed AQAP-1 for civilian useBritish Standards Institute (BSI) developed AQAP-1 for civilian use BS 5750BS 5750
  5. 5.  Calibration: the process of testing and adjustment of an instrument, kit, or test system to provide a known relationship between the measurement response and the value of the substance measured by the test procedure  Effectiveness: the extent to which planned activities are realized and planned results achieved  Efficiency: the relationship between the results achieved and the resources used
  6. 6.  Non-QMS processes – processes that are not contained in either the QSEs or in the laboratory’s path of workflow, such as those within the finance, sales, or marketing functions.  Path of workflow: the sequential processes in a laboratory’s activities that transform a request for examination into the laboratory information that is captured in the report of results.  Plan: written account of intended future course of actions aimed at achieving specific goal(s) or objective(s) within a specific timeframe and explains in detail what needs to be done, when, how, and by whom.
  7. 7.   Organization Customer Focus Facilities and Safety Personnel Purchasing and Inventory Equipment Process Management  Pre-examination Examination Post-examination Documents and Records Information Management Nonconforming Event Management Assessments Continual Improvement Pree-xamination Examination Post-examination Information Management  Quality System Essentials - those elements which must be applied to all operations in the service’s path of workflow  Path of Workflow - as it relates to the processes involved in the pre-, during and post- phases of delivery of services with the laboratory as an example
  8. 8. ! Internal Quality Control (IQC) Procedures ! External Quality Assessment (EQA) ! Quality Management
  9. 9. Internal Quality Control
  10. 10. ⇒ Done during daily routine work ⇒ Provides an immediate control ⇒ Errors are corrected immediately ⇒ Routinely collect and analyze data from every test run or procedure Why do we need Internal Quality Control? ! Ensure that test results are reliable (trustable) ! Ensure that test results are reproducible (Closeness of the results of assays of the same test carried under changed conditions) ! Control quality of daily routine work
  11. 11. Monitoring quality of laboratory testing, accuracy and precision of laboratory results
  12. 12.  Precise and Inaccurate  Precise and Accurate
  13. 13.  Imprecise and Inaccurate  Imprecise and ?? Accurate
  14. 14.  It ensures continual check that the laboratory’s work does not fluctuate and that reports are validated before they are released.  It is based on monitoring the procedures which are actually used for the tests in the laboratory. It includes: · Control charts with tests on control materials · Duplicate tests on all specimens or on a proportion of the specimens · Delta check, comparing current test results with previous results · Consistency of mean values of patient data
  15. 15.  Use 2-3 levels of controls covering the medical decision points  At least 20 control values over a period of 20-30 days for each level of control  Perform statistical analysis  Develop Levey-Jenning chart  Run -regularly- with patient samples  Monitor control values on chart using Westgard rules  Take immediate corrective action, if needed  Record actions taken (if any)
  16. 16.  QC material must be available in large quantities stored in small aliquots (Ideally should last for at least 1 year)  Always consider as Biohazardous  Requires very accurate reconstitution if needed  Always deal with and store as recommended by manufacturer
  17. 17.  Need data set of at least 20 points obtained over 20-30 days better by different operators in different times of day  Calculate mean, standard deviation, Coefficient of variation and determine target ranges  Develop Levey-Jenning charts  Plot –on the chart- control values each run/ day  Make decisions regarding acceptability of run using Westgard rules  Monitor over time and at defined intervals
  18. 18. 1. 192 mg/dL 2. 194 mg/dL 3. 196 mg/dL 4. 196 mg/dL 5. 160 mg/dL 6. 196 mg/dL 7. 200 mg/dL 8. 200 mg/dL 9. 202 mg/dL 10. 255 mg/dL 11. 204 mg/dL 12. 208 mg/dL 13. 212 mg/dL
  19. 19. 80 85 90 95 100 105 110 115 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Day Mean +1SD +2SD +3SD -1SD -2SD -3SD
  20. 20. 80 85 90 95 100 105 110 115 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Day Mean +1SD +2SD +3SD -1SD -2SD -3SD
  21. 21.  Ideally should have control values clustered around the mean (+/-2 SD) with little variation in the upward or downward direction  Imprecision = large amount of scatter around the mean. Usually caused by errors in technique  Inaccuracy = may see as a trend or a shift, usually caused by change in the testing process  Random error = no pattern. Usually poor technique, malfunctioning equipment
  22. 22. Random Error (RE): Imprecision  Causes: 1. Pipetting error 2. Temperature error 3. Mixing defect 4. Machine need troubleshooting  Systematic Error (SE): Inaccuracy  Causes: 1. Deterioration of control material 2. Deterioration of calibrator 3. Deterioration of reagents
  23. 23.  Allows determination of whether an analytical run/s (in control) or (out of control)
  24. 24. October 1, 2008
  25. 25. October 1, 2008
  26. 26.  When you're running 2 or 4 control levels, use the rules: 13s/22s/R4s/41s/10x  When you're running 3 control levels, use a set that works for multiples of threes: 13s/2of32s/R4s/ 31s/12x
  27. 27.  Rejection rule = Out of control= 1. Stop testing 2. Identify and correct problem 3. Repeat testing on pt samples and control 4. Don’t report pt results until problem is solved and controls indicate proper performance
  28. 28.  Change one variable at a time to troubleshoot an out of control test.  The variables are usually common to all instruments or procedure systems and include the following:  1. Try a fresh vial of QC  2. Try a new reagent (same lot)  3. Try a new consumable (water, part, solution, tubing) if applicable.  4. Try a new reagent (new lot)  5. Recalibrate (current calibrator)  6. Recalibrate (new lot calibrator)  If a system cannot be brought into control, notify senior staff. Do not process patient samples for the test affected.
  29. 29. When changing to a new lot number of control material, ideally there should be an overlap period while the new material is being analyzed to establish the new control limits. In cases where the overlap period is not sufficient, it is possible to establish the mean value for the new control material in a short time, over say a five-day period, or to start with the manufacturer’s values. Then apply the previous estimate of SD to establish the control limits. These control limits should be temporary, until sufficient data is collected to provide good estimates of both the mean and SD of the new material.
  30. 30.  New lots of a quality control material should be analyzed for each analyte in parallel with the lot of control material in current use.  Ideally, a minimum of at least 20 measurements should be made on separate days when the measurement system is known to be stable, based on QC results from existing lots.  If the desired 20 data points from 20 days are not available, provisional values may have to be established from data collected over fewer than 20 days.  Possible approaches include making no more than four control measurements per day for five different days
  31. 31.  Retained patients samples ◦ Original samples must be assayed in the lab under accepted control run conditions ◦ Stored aliquited immediately after finishing 1st analysis ◦ Storage conditions must meet the requirements for analytes to be measured ◦ Avoid repeated warming/ thawing ◦ Stability of the measurand must be carefully respected ◦ Better to be alternating with QC material ◦ Result of the 1st assay is used as the base for comparison and calculation (as if gold value) ◦ Allowable analytical imprecision is used for judgment of acceptance or rejection ◦ Data calculated from biological variations/ CLIA limits are used for the issue
  32. 32.  Result comparison with an in-control method/ instrument/ procedure for the measurand ◦ The in-control instrument/ method is considered the reference one ◦ Not more than one hour time gap between the parallel assays ◦ Principles of assays must be considered if different ◦ Inaccuracy limits is used for comparison ◦ Data calculated from biological variations/ CLIA limits are used for the issue
  33. 33.  Individual Patient Results: ◦ Clinical Correlations ◦ Correlation with other laboratory tests ◦ Intralaboratory duplicates ◦ Delta check with previous test results ◦ Limit Check  Multiple Patients: ◦ Test distribution statistics ◦ Monitoring patients means
  34. 34. QUESTIONS
  35. 35. External Quality Control
  36. 36. Inter-laboratory comparisons and other performance evaluations that may extend throughout all phases of the testing cycle, including interpretation of results; determination of individual and collective laboratory performance characteristics of examination procedures by means of interlaboratory comparison
  37. 37. A program in which multiple samples are periodically sent to members of a group of laboratories for analysis and/or identification, in which each laboratory’s results are compared with those of other laboratories in the group and/or with an assigned value, and reported to the participating laboratory and others
  38. 38.  Introduced into laboratory medicine more than 60 years ago to address that results for aliquots of the same sample were different when measured by different laboratories.  PT/EQA programs are now an essential component of a laboratory’s quality management system.  PT/EQA is a component of laboratory accreditation requirements
  39. 39.  Ideal samples for a PT/EQA program would fulfill a range of criteria: ◦ Stable for the conditions under which they will be transported and stored ◦ Homogeneous across all the aliquots produced ◦ Have analyte concentrations that include the expected clinical range ◦ Include appropriate sample types (e.g., urine, whole blood, serum) ◦ Available in sufficient volume ◦ Inexpensive enough for cost not to be an impediment ◦ Behave in clinical laboratory measurement procedures in ◦ the same manner as patient samples ◦ Samples from a single donor or pooled samples from multiple donors can be used
  40. 40.  Samples have traceable reference values (when reference values are used)  Behave like patient samples (commutability)  The laboratory may also consider cost  Similarity of PT samples to patient samples  Method compatibility with peer groups  Size of peer groups  Frequency of challenges  Timeliness and usefulness of reports  Educational content  Customer service
  41. 41.  category 1 programs are limited because of: • Technical aspects such as a lack of reference measurement procedures, absence of certified reference materials, inability to prepare commutable samples; • Practical considerations such as the difficulty of preparing samples covering the full measuring interval and the complicated logistics of preparation and distribution of fresh or frozen samples; • Psychological limitations such as lack of awareness of the quality factors important in PT/EQA or unwillingness to adopt these; • Economic concerns because distributing commutable samples in sufficient quantity and providing target values with reference measurement procedures is expensive
  42. 42.  PT samples should be tested in the same manner as patient samples, to the extent possible  Some laboratories may improperly test PT samples differently from patient samples, by repeat testing of PT samples when patient samples are tested only once, or by having a specific analyst test PT samples rather than rotating PT testing among all the personnel who perform patient testing.  There should be no attempt to produce “best” results by replicate analysis or testing immediately following internal QC or recalibration
  43. 43.  The core content of the result report should resemble as closely as possible the content of a routine clinical result report  If the usual report is deemed inappropriate for a PT report, it may equally be inappropriate for a clinical report  A copy of all PT reports should be retained within the laboratory in order to verify the information handling by the PT provider.
  44. 44.  Sending a set of samples from an organizing body to a group of participating laboratories for measurement of 1 or more analytes present in the samples  Samples are intended to simulate the clinical samples usually measured  Laboratories are not informed of the analyte concentration or activity in a particular sample  Timely schedules for running and reporting results are included  Laboratory perform measurements in the same manner as for patient samples  Results for the samples are returned to the PT/EQA organizer for evaluation of conformance to the expected results
  45. 45.  The organizer prepares a report that includes: ◦ the results reported by a laboratory ◦ the method used for the measurements ◦ the target values expected for each analyte ◦ evaluation of whether the individual laboratory’s results met the performance requirements ◦ Reports may also include evaluation of the performance of the various measurement procedures used by the participants  The laboratory evaluates its performance according to the provider report
  46. 46.  Limits or quality standards around the target value are established against which performance can be assessed by: ◦ Regulatory: wider like US CLIA, German Rili-BAeK ◦ Statistical: ± 2-3 SD ◦ Clinically-based: on a difference that may affect clinical decisions or on biological variation  Total error limits including bias, imprecision, and analytical nonspecificity can contribute to the variation in a single result  Have different limits to separately assess bias and imprecision when replicate samples are included  PT/EQA limits are set as a minimum standard to identify results that indicate poor performance. Thus, meeting these standards may not indicate that performance is optimal nor that performance meets all clinical needs
  47. 47.  Determines the accuracy by comparing PT/EQA results to those from a reference measurement procedure or from a designated comparison method or to an all-participant (or all-method) mean/ median. This arrangement is now referred to as accuracy-based evaluation  Assess agreement with other measurement procedures and imprecision among all methods as well as within a method group  Peer group evaluation provides valuable information to assess quality, verifying that a laboratory is using a measurement procedure in conformance to the manufacturer’s specifications and to other laboratories using the same technology
  48. 48.  PT/EQA result represents 1 point in time and will occasionally be a random error  Repeat the measurement using a stored aliquot of the PT/EQA sample (assuming the measurand was stable on storage) to confirm if the problem has persisted or to conclude that the problem no longer exists and the original unacceptable result was a random event, and therefore no corrective action is indicated. If the repeated result is still unacceptable, the laboratory conducts further investigation to identify the root cause, and then initiates corrective action
  49. 49. • Gather data related to the testing event to include records of calibration, reagent use, QC results, and maintenance procedures; • Obtain other data on assay performance, e.g., previous PT/EQA results and relevant patient data; • Identify the root cause of the error; • Take corrective action and preventive action if indicated; • Monitor the success of the corrective action; • Document the investigation and the corrective action.
  50. 50. • Was the testing material received in satisfactory condition? • Was the appropriate sample tested? • Were procedures for sample preparation followed? • Was the appropriate method used for analysis? • Was the method performed according to documented procedures? • Were appropriate reagents and controls used? • Was equipment operated according to documented procedures?
  51. 51. • Was equipment appropriately maintained? • Was QC acceptable at the time of testing PT samples? • Were results interpreted appropriately? • Has this problem occurred previously with PT samples? Are data consistent with previous PT distributions? Is there a trend leading to failure or is the current set completely unexpected? • Did repeat testing on the properly stored residual sample produce similar results? • Were patient results acceptable at the time of PT testing?
  52. 52. 1. Clerical error; 2. Methodologic problem; 3. Equipment problem; 4. Technical problem; 5. Problem with proficiency testing materials; 6. Problem with evaluation of results; and 7. No explanation after investigation: An investigation fails to reveal an explanation for an unacceptable PT result 19 to 24% of the time
  53. 53.  Split-Sample With Another Laboratory  Internal Split-Sample Procedures  Audit-Sample Procedure  Analysis of Manufacturer’s Product Calibrator or Trueness Control Material  Analysis of Interlaboratory Quality Control Data  Averages of Patient Data
  54. 54.  Reference Intervals  Reevaluation of Interpreted Results  Direct Observation of Technique-Dependent Tests  Clinical Correlation Studies  Government and University Interlaboratory Comparison Programs  Analysis of Data From Qualitative Alternative Assessment Procedures