STATISTICAL QUALITY CONTROL (SQC) SQC evaluates the measurement procedure by periodically assaying QC materials for which the correct result is known.

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1 CONTROL OF ANALYTICAL QUALITY R. Mohammadi Biochemist (Ph.D.) Faculty member of Medical Faculty

2 STATISTICAL QUALITY CONTROL (SQC) SQC evaluates the measurement procedure by periodically assaying QC materials for which the correct result is known. IQC assumes a Gaussian (normal) distribution of QC results in which 68.2% results are in ± 1 SD 94.5% results are in ±2 SD 99.7% results are in ±3 SD

3 Statistical Process Control (SPC)

4 Statistical Process Control (SPC)

5 ANALYTICAL ERRORS Random Errors Systematic Errors

6 Problem SD + 2 SD + 1 SD X -1 SD - 2 SD -3 SD

7 Problem SD + 2 SD + 1 SD X -1 SD - 2 SD -3 SD

8 Performance Characteristics of A Control Procedure We Have Inherent or background random error which h produce noise Analytical errors which produce signals We must consider Probability of false rejection (P fr ) Probability of error detection (P ed ed )

9 Factors Affecting on SQC Results Interpretation t ti QC Material Mean and SD Rules Method Sigma Quality Metrics

10 QC MAERIALS

11 SELECTON OF QC MATERIALS Nature (Matrix & Source) of Material Analyte Stability (Before and After Opening) Volume Amount Include Whole Process Analyte Concentration Assayed or Unassayed Dependent and Independent

12 DETERMINATION OF MEAN AND STANDARD DEVIATION

13 نالیز ابتدایی ماده کنترلی جهت تعیین ا میزان هدف و انحراف معیار به آناليز تعداد کافی نمونه طی دوره ای و وجود دارد که سيستم بخوبی وی يز ١) نياز است و عدم دقت مورد انتظار مربوط به شرايط پايدار وجود دارد. کاليبره روز مختلف) (طیی ٢٠ متفاوت زمان ٢٠ طی حداقل آناليز ٢٠ نياز به ٢) حداقل ويال ننمونه می باشد که بتواند ا پايداری آناليت را بخوبی مورد ا ارزيابی روی يک بر دھد. قرار عملی نباشد مقادير ھدف موقتی با تعداد روزه ٢٠ وری صورتی که پروو پروتوکل در (٣ کمتر تعيين می گردد و با دسترسی به نتايج بيشتر روزسازی مقادير انجام نمونه شود. می ازشا شماره جديد ماده مشابھی ا استفاده می شود ا آزمايشگاه از ميانگين جديد وقتی ۴) ۴ آمده به عنوان ميانگين ھدف در کنار انحراف معيار قبلی استفاده می کند. بدست از ي ميانگين و انحراف ير معيار تجمعی انعکاس بھتری از ري شرايط واقعی ۵) استفاده است

14 ا نالیز روتین ماده کنترلی جهت تعیین احتمالی تصادفی و نظامند خطاهای می شود برای ھر آناليت حداقل از دو ماده کنترلی در سطوح متفاوت ١) توصيه تصميم گيری پزشکی استفاده شود. کنترل ھمانند نمونه بيمار مورد آناليز قرار می گيرد و قبل از گزارش ٢) نمونه نتايج بيمار داده ھای نمونه کنترل مورد بررسی و تفسير قرار می گيرند و بعد از نتايج بيماران را گزارش نمود. اين نتايج می توان تأييد پايداری سيستم اندازه گيری شاخص اصلی تعيين فراوانی نياز به آزمون يک (٣ کنترلی است. نمونه

15 معرف مر شماره ساخت تغيير

16 تغيير شماره ساخت معرف

17 ا ناليت از دو روشبري براي اندازه گيري يك استفاده

18 WESTGARD MULTIRULE SYSTEM

19 WESTGRAD RULES 1 2S 1 3S 2 2S R 4S 4 1S 10 X

20 1 2s control rule + 3 SD + 2 SD + 1 SD X -1 SD - 2 SD -3 SD

21 1 3s control rule + 3 SD + 2 SD + 1 SD X -1 SD - 2 SD -3 SD

22 2 2s control rule + 3 SD + 2 SD + 1 SD X -1 SD - 2 SD -3 SD

23 R 4 R 4s control rule + 3 SD + 2 SD + 1 SD X -1 SD - 2 SD -3 SD

24 4 1s control rule + 3 SD + 2 SD + 1 SD X -1 SD - 2 SD -3 SD

25 10 x control rule + 3 SD + 2 SD + 1 SD X -1 SD - 2 SD -3 SD

26 METHOD SIGMA QUALITY METRICS

27 X = 90 mg/dl ; TEa = 10% ; SD = 3 mg/dl ; %CV = %3.3 Lower Process Upper Spec.limit Mean Spec.limit Three Sigma Process 3σ 2σ 1σ 0 1σ 2σ 3σ

28 X = 90 mg/dl ; TEa = 10% ; SD = 1.5 mg/dl ; %CV = %1.7 Lower Process Upper Spec.limit Mean Spec.limit Six Sigma Process 6σ 5σ 4σ 3σ 2σ 1σ 0 1 σ 2σ 3σ 4σ 5σ 6σ

29 Lower Process Upper Spec.limit Mean Spec.limit 1.5σ 1.5σ shift shift Six Sigma Process 6σ 5σ 4σ 3σ 2σ 1σ 0 1 σ 2σ 3σ 4σ 5σ 6σ

30 Increasing P ed By Using Narrower Control limits e.g. 1 2S against 1 3S By Using More QC Materials e.g. Low, Normal and High By Using Fewer Control Data eg e.g. 8 X against 12 X By Using Multirules e.g. 1 3S /2 2S

31 Recommended Rules For Methods with different sigma Sigma N Rule(s) S S S or 1 3S /2 2S /R 4S /4 1S S /2of3 2S R 4S /3 1S /6x

32 EXTERNAL QUALITY ASSESSMENT

33 MATRIX EFFECT Noncommutable Samples EQA organizers often use commercially QC materials specifically prepared to ease transportation and storage, having relatively low cost, and exhibits a low vial to vial variability. For this, control materials are commercially prepared by adding preservatives and other substances which may have adverse effects on the physicochemical properties of samples 8. So, QC materials are frequently are noncommutable with clinical patient sample and they may produce significantly differenent results with different assays.

34 MATRIX EFFECT Commutable Samples Commutable samples are typically prepared by pooling clinical patient samples with minimal processing or additives to avoid any alteration of sample matrix When commutable samples can be prepared, the results reflect what would be expected if patient samples were sent to each of the different laboratories. So. Agreement among different laboratories and methods can be correctly evaluated. It has been challenging to prepare commutable materials for use in large PT programs. However, use of commutable materials adds substantial value to the information obtained from the results.

35 Matrix Effect 9 th EQAP HbA1c Analysis Method n Mean %CV Pars Azmon Pishtaz Teb Biosystem Roche NycoCard Total

36 Matrix Effect 11 th EQAP HbA1c Analysis Method n Mean %CV Pars Azmon Pishtaz Teb Biosystem Roche NycoCard Total

37 Matrix Effect 15 th EQAP HbA1c Analysis Method n Mean %CV Pars Azmon Pishtaz Teb Biosystem Roche NycoCard Total

38 Matrix Effect 17 th EQAP HbA1c Analysis Method n Mean %CV Pars Azmon Pishtaz Teb Biosystem Roche NycoCard Total

39 Matrix Effect 18 th EQAP HbA1c Analysis Method n Mean %CV Pars Azmon Pishtaz Teb Biosystem Roche NycoCard Total

40 DATA ANALYSIS FOR INTERPRETATION OF RESULTS S Evaluation of performance of each participant needs to establish two values: 1) Assigned (target) value of the test material 2) Acceptable range Different methods can be used to establish these estimates, but there is no standard protocol statistical parameters

41 ESTABLISHING ASSIGNED VALUE There are three methods 1) The addition of a known amount or concentration of analyte to a base material containing none 2) The use of a Consensus value produced by a group of expert or referee laboratories using best possible methods 3) The use of a consensus value produced in each round of EQA, and based on the results by participants

42 ESTABLISHING ASSIGNED VALUE FROM PARTICIPANT RESULTS assigned value is consensus value (trimmed mean value) derived d from all results submitted by participants in the scheme of that analyte Practical experiences has shown that the consensus value usually agrees closely with the true value in schemes with a large number participants Consensus value may not be valid in two conditions: 1) Numbers of laboratories is small 2) A large proportion of participants have a significant analytical bias

43 ESTABLISHING ACCEPTABLE RANGE After calculating method relating consensus value, acceptability criteria must be establish For this, statistical parameters are calculated, including 1) Mean (X) 2) Standard Deviation (SD) 3) Coefficient of Variation (CV) CV% = SD X x 100

44 ESTABLISHING ACCEPTABLE RANGE Acceptability criteria may be 1) Interval based on group SD (e.g., X ± 2SD) 2) Fixed percentage (e.g., X ± constant percent) 3) Fixed interval (e.g., X ± constant amount) Alternatively, scoring system may be used 1) Bias Index Score (BIS) 2) Variance Index Score (VIS) 3) Standard Deviation Index or Interval (SDI)

45 Z Score Z = X lab -X peer SD peer SDI = X lab -X peer SD BIS = SD peer X lab -X peer X peer x 100 CCV%

46 Chosen Coefficient of Variation (CCV) CCV are the lowest CVs obtained for particular determinations during first tt two years of fth the EQAS It is kept constant so that improvements in the performance of fl laboratories can be detected t d

47 Is Numbers of member in peer group adequate? Yes Is CV% of peer group suitable? Yes No Data analysis is not valid No What Is the result of data analysis? Excellent or Good Warnning Unacceptable Need no action Follow next EQA Result Need error detection and correction

48 Peer GROUP PROGRAM Peer Group Program Is A Combination of Internal And External Quality Control When EQC Is Used In Conjunction With Daily IQC, This Program Will Give Laboratories Added Confidence in Their Patient Test Results All Labs Use The Same Control Material and Report Their Results Daily Data Are Analyzed And Reported Monthly As SDI and CVR

INTERNAL QUALITY CONTROL ( Q I C) QC)

INTERNAL QUALITY CONTROL ( Q I C) QC) EXTERNAL QUALITY ASSESSMENT PROGRAM (EQAP) BIOCHEMISTRY DEPARTMENT R. Mohammadi Biochemist (Ph.D.) Faculty member of Medical Faculty TWO COMPLEMENTARY COMPONENETS OF TQM ARE Internal Quality Control (IQC)