Quality assignment(1)
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Quality assignment(1) Presentation Transcript

  • 1. Quality ControlIT IS A BASIC SAFETY PRACTICE TOMONITOR ANALYTICAL QUALITY OFMEASUREMENT.To detect changes from stable day to dayoperation and eliminate reporting of results withmedically important errors.`
  • 2. OBJECTIVES1.To determine how to establish the analytical goal and quality control scheme /schedule in your lab2.To identify the Quality control charts and quality control roles3.To identify the new rules of west guard.4. Overview of the CLSI guide lines C24. 2
  • 3. FIRST OBJECTIVE To determine how to establish theanalytical goal and quality control ! scheme /schedule in your lab 3
  • 4. Data we needed to design Quality Control1.Commercial QC material2.Manufacturers’ kit inserts .3. Doing it for yourself is, as usual, the safest method.4.EQAS programs . 4
  • 5. Designing the internal quality control protocolDefine the level of quality that the laboratory wants to.1 attain for a determined test (the analytical quality(.specification.know the stable analytical performance for this test . 2a control rule (control limits and number of controls per . 3( .run:Assure quality of results. 4 a. analytical imprecision and bias b. EQAS 5
  • 6. Proficiency testing# Inter laboratory Comparison Programs Help Improve Laboratory Performance.#
  • 7. Define Analytical Goal Two main strategies for analytical quality specifications based on.calculation of imprecision and bias 7
  • 8. ?How to establish your analytical goalThe underlying principle of ‘measurement*uncertainty’ is that a laboratory should know how.precisely they can measure any particular analyteTwo main strategies for analytical quality*specifications based on biology have beenevaluated for imprecision and bias (in combinationwith imprecision), respectively 8
  • 9. Challenges to set analytical Goal External InternalPermenant External Internal :Method :ImplementationPermenant :Method Analytical principle Choice of conditions :Implementation Analytical Equipment principle In house equipment Choice of conditions Reagents Equipment ,In house reagents In house equipment Reagents)choice of producer( ,.Time, Temperature, In house reagents Volume, etc )choice of:producer( Standardization .:StandardizationVolume, etc Time, Temperature, :Standardization :Standardization Traceability of calibration of Traceability calibration Calibration function Calibration functionVariableVariable :Batches :Batches ::Performance Performance )Reagents Reagents ) (variability (variability in house reagents in house reagents Calibrators Calibrators ..Training, Maintenance, Training, Maintenance, etc etc Consumables Consumables Control with trouble-shooting Control with trouble-shooting 9 Documentation Documentation
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  • 12. Relevance to customersAll thesecomplicatedprocesses toprovide theappropriatequality for ourpatient cares 12
  • 13. Setting Goals For Q.C Performance1.Maximum allowable number of unacceptableresults, due to an out of control error conditions.2.Maximum allowable probability of reportingunacceptable results.3.Minmum acceptable probability of detecting anout of control error condition.4.Maximum acceptable probability of falserejection. *Main aim is to Maximize probability to detectan out of control condition for measurementprocedure , while minimize probability for falseQ.C alerts. 13
  • 14. Analysis of Control MaterialsA stable control which mimics patient’s sample is analyzed (DAY TO DAY OR SET TO SET(Need data set of at least 20 points, obtained over a 30 day periodCalculate mean, standard deviation, coefficient of variation; determine target ranges
  • 15. CLIA proficiency testing criteria for acceptableanalytical performance:
  • 16. Objective2.To identify the Quality control charts and quality control roles3.To identify the new rules of west guard. 21
  • 17. Monitoring QC DataDevelop Levey-Jennings chart.Plot control values each run, make decision regarding acceptability of run.Monitor over time to evaluate the precision and accuracy of repeated measurementsReview charts at defined intervals, take necessary action, and document
  • 18. Levey-Jennings ChartA graphical method for displaying control results and evaluating whether a procedure is in-control or out-of- controlControl values are plotted versus timeLines are drawn from point to point to accent any trends, shifts, or random excursions
  • 19. Levey-Jennings ChartThe Levey-Jennings chart usually has the days of the month plotted onthe X-axis and the control observations plotted on the Y-axis.On the right is the Gaussian or "bell-shaped" curve turned on its side toshow the correlation of the curve to the chart (ie, fewer data pointsshould appear on the upper and lower extremities of the chart, since the"bell" is thinner farther from the mean).By observing the data plotted in the L-J chart, we can determine if testresults are in control and accurate, or if test results are not in controland consequently unacceptable. 24.
  • 20. Levey-Jennings Chart Calculate the Mean and Standard Deviation; Record the Mean and +/- 1,2 and 3 SD Control Limits3SD+1152SD+ 1101SD+ 105Mean 1001SD- 952SD- 903SD- 85 80 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
  • 21. Levey-Jennings Chart - Record Time on X-Axis and the Control Values on Y- Axis 115 110 Control Values (e.g. mg/dL) 105 100 95 90 85 80 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 (Time (e.g. day, date, run number
  • 22. Levey-Jennings Chart -Plot Control Values for Each Run 115 110Control Values (e.g. mg/dL) 105 100 95 90 85 80 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 (Time (e.g. day, date, run number
  • 23. Levey-Jennings Chart - Record and Evaluate the Control Values3SD+ 1152SD+ 1101SD+ 105Mean 100 951SD-2SD- 903SD- 85 80 Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
  • 24. Look for assignable In control Out of control ! cause ! UCL Problem Natural corrected 6σ VariationTarget= Mean 3σ LCL Time Samples Natural variation
  • 25. “Allows determination of whether an analytical run is “in-control” or “out-of-control”
  • 26. Westgard Rules are a multi role QC procedure1-West-gard rules: (Regular twice entry for Q.C) 3s, 1 2s, 2 2s , R 4s, 4 1s, 10x (& modifications 1 ) 8x, 12xRecent west-gard rules, fit better and are easier-2to apply in situations where 3 different control:materials are being analyzed 2of3 2s, 3 1s, 6x & 9xA related control rule that is sometimes used-3":looks for a "trend 7T 31
  • 27. Westgard Rules are a multirule QC procedure 13s refers to a control rule that is commonly used . with a Levey Jennings chart A run is rejected when a single control measurement exceeds the mean plus 3s or the .mean minus 3s control limit 32
  • 28. 12s refers to the control rule that is commonly used with aLevey-Jennings chart single control measurement exceeds. the mean plus 2s or the mean minus 2s control limit This rule is used as a warning rule to trigger carefulinspection of the control data by the following rejection rules . 33
  • 29. 22s - reject when 2 consecutive controlmeasurements exceed the same mean plus 2s. or the same mean minus 2s control limit 34
  • 30. R4s - reject when 1 control measurement in a group exceeds the. mean plus 2s and another exceeds the mean minus 2s 35
  • 31. 41s - reject when 4 consecutive controlmeasurements exceed the same mean plus 1s. or the same mean minus 1s control limit 36
  • 32. 10x - reject when 10 consecutive control measurements fall. on one side of the mean :some modifications8x - reject when 8 consecutive control measurements fall on one side of the mean12x - reject when 12 consecutive control measurements fall. on one side of the mean 37
  • 33. In situations where 3 different control materials arebeing analyzed, some other control rules fit better and:are easier to apply, such as2of32s - reject when 2 out of 3 control measurementsexceed the same mean plus 2s or mean minus 2s controllimit ; 38
  • 34. 31s - reject when 3 consecutive controlmeasurements exceed the samemean plus 1s or mean minus 1s.control limit 39
  • 35. some modification:6x - reject when 6 consecutive controlmeasurements fall on one side of themean. 40
  • 36. A related control rule that is sometimes used,looks for a "trend" where several controlmeasurements in a row are increasing or decreasing7T - reject when seven control measurementstrend in the same direction, i.e., get progressivelyhigher or progressively lower.there are two types of errors, random and systematicthe multirule combines the use of two types ofrules to help detect those two types of errors. 41
  • 37. Corrective action1- Determine the type of error occurring onthe basis of the rule violated.2-Refer to trouble-shooting guides to identifypossible causes for the type of error indicatedby the control rule that was violated. 42
  • 38. There are two types of errors, random and systematicthe multi rule combines the use of two types of rules to helpdetect those two types of errors: Type of Error Control rule that detects it Random error 13s, R4s Systematic error 2s, 4 1s, 2of3 2s, 3 1s, 6x, 8x, 9x, 10x, 2 12x, cusum 43
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  • 43. Correct the problem, then analyze control- 3.samples again to assess control status4- Repeat or verify the results on the patientsamples once the method has been demonstratedto be in-control.5- Consult a supervisor for any decision to reportpatient results when a run is out-of-control. 48
  • 44. OBJECTIVEOverview of the CLSI guide lines .C24 49
  • 45. ?Who is CLSIClinical and Laboratory Standards InstituteANSI-accredited, global, nonprofit standards•development organizationCLSI has over 2,000 members – organizations such•as IVDmanufacturers, hospital laboratories, reference,laboratories, universitiesprofessional associations, and government agencies 50
  • 46. CLSI –C24:Q.C planning processDefine Quality requirement inn the form of.1.Allowable total error.Select suitable Q.C material.2Obtain estimates of methods of impersion and bias.3.Identify traditional control rules.4Predict performance in terms of probabilities for.5rejection (including false rejection),through the.available charts/graphsSet goals for Q.C performance as probability of error.6detection of 90%,and a probability of false rejection.of 5% chanceDetect critical systemic errors using suitable.7.graphical tools 51
  • 47. Calculating Sigma Level of critical systemic error=Critical systemic error total allowable error - Bias] ) %[mean)/Impercision=SIGMA-METRICCritical systemic error + 1.65 52
  • 48. CLSI EP23 Guideline Laboratory Quality Control Based on RiskManagement—Proposed Guidelineguidance to enable labs to develop effective, cost-efficient:QC protocols to Reduce negative impact of test system’s-.limitations Monitor immediate and extended test-.performance 53
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  • 51. For each risk, a mitigation strategy is found that will.reduce the residual risk to an acceptable levelSum of all QC elements (manufacturer provided andlaboratory added) becomes the laboratory’s QC plan.specific to this device and the laboratory environment 56
  • 52. CLSI EP23 GuidelineDoesn’t replace surrogate QC, butincorporates surrogate QC toaddress the potential for certainrisksUtilizes a risk managementapproach to developing a.customized QC planProvides a scientific basis forjustifying QC strategies (useful for(lab inspectors 57