CONTROL OFCONTROL OFCONTROL OF CONTROL OF ANALYTICALANALYTICAL QUALITYQUALITYANALYTICAL ANALYTICAL QUALITYQUALITY

R. R. MohammadiMohammadiBiochemist (Ph D )Biochemist (Ph D )Biochemist (Ph.D.)Biochemist (Ph.D.)

Faculty member of Medical FacultyFaculty member of Medical Faculty

STATISTICAL QUALITY CONTROL (SQC)STATISTICAL QUALITY CONTROL (SQC)STATISTICAL QUALITY CONTROL (SQC)STATISTICAL QUALITY CONTROL (SQC)

SQC evaluates the measurementSQC evaluates the measurementSQC evaluates the measurement SQC evaluates the measurement procedure by periodically assaying QC procedure by periodically assaying QC materials for which the correct result ismaterials for which the correct result ismaterials for which the correct result is materials for which the correct result is known.known.IQC assumes a Gaussian (normal)IQC assumes a Gaussian (normal)IQC assumes a Gaussian (normal) IQC assumes a Gaussian (normal) distribution of QC results in whichdistribution of QC results in which

6868..22% results are in % results are in ±± 1 1 SDSD9494..55% % results are in results are in ±± 2 2 SDSD9999..77% % results are in results are in ±± 3 3 SDSD

Statistical Process Control (SPCStatistical Process Control (SPC))Statistical Process Control (SPCStatistical Process Control (SPC))

Statistical Process Control (SPC)Statistical Process Control (SPC)Statistical Process Control (SPC)Statistical Process Control (SPC)

ANALYTICALANALYTICALERRORSERRORSERRORSERRORS

R d ER d ERandom ErrorsRandom Errors

Systematic ErrorsSystematic ErrorsSystematic ErrorsSystematic Errors

ProblemProblem 11Problem Problem 11

+ 3 SD

+ 2 SD

+ 1 SD

2 SD

- 1 SDX

- 2 SD

- 3 SD

ProblemProblem 22Problem Problem 22

+ 3 SD

+ 2 SD

+ 1 SD

2 SD

- 1 SDX

- 2 SD

- 3 SD

Performance Characteristics of A Performance Characteristics of A C t l P dC t l P dControl ProcedureControl Procedure

We HaveWe HaveWe HaveWe HaveInherent or background random errorInherent or background random error

hi h d ihi h d iwhich produce noisewhich produce noiseAnalytical errors which produce signalsAnalytical errors which produce signalsWe must considerWe must considerProbability of false rejection (Probability of false rejection (PPff ))Probability of false rejection (Probability of false rejection (PPfrfr))Probability of error detection (Probability of error detection (PPeded))

Factors Affecting on Factors Affecting on SQC R lt I t t tiSQC R lt I t t tiSQC Results InterpretationSQC Results Interpretation

QC MaterialQC MaterialQC MaterialQC MaterialMean and SDMean and SDR lR lRulesRulesMethod Sigma Quality MetricsMethod Sigma Quality Metrics

QC MAERIALSQC MAERIALS

SELECTON OF QC MATERIALSSELECTON OF QC MATERIALSSELECTON OF QC MATERIALSSELECTON OF QC MATERIALS

Nature (Matrix & Source) of MaterialNature (Matrix & Source) of MaterialNature (Matrix & Source) of MaterialNature (Matrix & Source) of MaterialAnalyteAnalyte Stability (Before and After Opening)Stability (Before and After Opening)VolumeVolumeVolumeVolumeAmountAmountInclude Whole ProcessInclude Whole ProcessInclude Whole ProcessInclude Whole ProcessAnalyteAnalyte ConcentrationConcentrationAssayed orAssayed or UnassayedUnassayedAssayed or Assayed or UnassayedUnassayedDependent and IndependentDependent and Independent

DETERMINATION OF MEAN ANDDETERMINATION OF MEAN ANDDETERMINATION OF MEAN AND DETERMINATION OF MEAN AND STANDARD DEVIATIONSTANDARD DEVIATION

نالیز ابتدایــی ماده کنترلی جهت تعیینٓنالیز ابتدایــی ماده کنترلی جهت تعیینآا

میزان هدف و انحراف معیارمیزان هدف و انحراف معیار

نياز به آناليز تعداد کافی نمونه طی دوره ای وجود دارد که سيستم بخوبی نياز به آناليز تعداد کافی نمونه طی دوره ای وجود دارد که سيستم بخوبی ) ) ١١ ی)) و م ي ر و و ور ی و ی يز ز یي و م ي ر و و ور ی و ی يز ز ي..کاليبره است و عدم دقت مورد انتظار مربوط به شرايط پايدار وجود داردکاليبره است و عدم دقت مورد انتظار مربوط به شرايط پايدار وجود دارد

) ) روز مختلفروز مختلف ٢٠٢٠طی طی ((زمان متفاوت زمان متفاوت ٢٠٢٠آناليز طی حداقل آناليز طی حداقل ٢٠٢٠حداقل نياز به حداقل نياز به ) ) ٢٢ا ز ا خ ا ت آنال ا ا ان ت که اش نه ن ال اک ز ا خ ا ت آنال ا ا ان ت که اش نه ن ال بر روی يک ويال نمونه می باشد که بتواند پايداری آناليت را بخوبی مورد ارزيابی بر روی يک ويال نمونه می باشد که بتواند پايداری آناليت را بخوبی مورد ارزيابی ک

..قرار دھدقرار دھدپروتوکل))٣٣ که صورتی پروتوکلدر که صورتی تعداد٢٠٢٠در با موقتی ھدف مقادير نباشد، عملی تعدادروزه با موقتی ھدف مقادير نباشد، عملی روزه و ) ) ی پرو ور و ر ی پرو ور ی ب ر و ير ب ی ی ب روز و ير ب ی روز

نمونه کمتر تعيين می گردد و با دسترسی به نتايج بيشتر، روزسازی مقادير انجام نمونه کمتر تعيين می گردد و با دسترسی به نتايج بيشتر، روزسازی مقادير انجام ..می شودمی شود

انگ))۴۴ از شگا ا آز ش تفا ا شا ا ا ش از انگقت از شگا ا آز ش تفا ا شا ا ا ش از قت وقتی از شماره جديد ماده مشابھی استفاده می شود ، آزمايشگاه از ميانگين جديد وقتی از شماره جديد ماده مشابھی استفاده می شود ، آزمايشگاه از ميانگين جديد ))۴۴. . بدست آمده به عنوان ميانگين ھدف در کنار انحراف معيار قبلی استفاده می کندبدست آمده به عنوان ميانگين ھدف در کنار انحراف معيار قبلی استفاده می کند

واقعی))۵۵ شرايط از بھتری انعکاس تجمعی معيار انحراف و ميانگين از واقعیاستفاده شرايط از بھتری انعکاس تجمعی معيار انحراف و ميانگين از استفاده ی )) ي و ر ز ری س بھ ی ج ر ي ر ين و ي ز ی ي و ر ز ری س بھ ی ج ر ي ر ين و ي ز استاست

نالیز روتین ماده کنترلی جهت تعیینٓنالیز روتین ماده کنترلی جهت تعیینآا

خطاهای احتمالی تصادفی و نظامندخطاهای احتمالی تصادفی و نظامند

توصيه می شود برای ھر آناليت حداقل از دو ماده کنترلی در سطوح متفاوت توصيه می شود برای ھر آناليت حداقل از دو ماده کنترلی در سطوح متفاوت ) ) ١١..تصميم گيری پزشکی استفاده شودتصميم گيری پزشکی استفاده شود

نمونه کنترل ھمانند نمونه بيمار مورد آناليز قرار می گيرد و قبل از گزارش نمونه کنترل ھمانند نمونه بيمار مورد آناليز قرار می گيرد و قبل از گزارش ) ) ٢٢نتايج بيمار، داده ھای نمونه کنترل مورد بررسی و تفسير قرار می گيرند و بعد از نتايج بيمار، داده ھای نمونه کنترل مورد بررسی و تفسير قرار می گيرند و بعد از

نمود گزارش را بيماران نتايج توان م نتايج اين نمودتأييد گزارش را بيماران نتايج توان م نتايج اين ..تأييد اين نتايج می توان نتايج بيماران را گزارش نمودتأييد اين نتايج می توان نتايج بيماران را گزارش نمودتأييدپايداری سيستم اندازه گيری شاخص اصلی تعيين فراوانی نياز به آزمون يک پايداری سيستم اندازه گيری شاخص اصلی تعيين فراوانی نياز به آزمون يک ) ) ٣٣

..نمونه کنترلی استنمونه کنترلی است

رفتغيير شماره ساخت معرفتغيير شماره ساخت معرف ت ر م رفيير ت ر م يير

تغيير شماره ساخت معرفتغيير شماره ساخت معرف

ناليتٓناليتاستفاده از دو روش براي اندازه گيري يك آياستفاده از دو روش براي اندازه گيري يك ا ي يري ز بري روش و يز ي يري ز بري روش و ز

WESTGARDWESTGARDWESTGARD WESTGARD MULTIRULE SYSTEMMULTIRULE SYSTEM

WESTGRAD RULESWESTGRAD RULESWESTGRAD RULESWESTGRAD RULES

1122SS1122SS1133SS2222SS2222SSRR44SS444411SS1010XX

1122 control rulecontrol rule1122ss control rulecontrol rule

+ 3 SD

+ 2 SD

+ 1 SD

2 SD

- 1 SDX

- 2 SD

- 3 SD

1133 control rulecontrol rule1133ss control rulecontrol rule

+ 3 SD

+ 2 SD

+ 1 SD

2 SD

- 1 SDX

- 2 SD

- 3 SD

2222 control rulecontrol rule2222ss control rulecontrol rule

+ 3 SD

+ 2 SD

+ 1 SD

2 SD

- 1 SDX

- 2 SD

- 3 SD

RR44 control rulecontrol ruleRR44ss control rulecontrol rule

+ 3 SD

+ 2 SD

+ 1 SD

2 SD

- 1 SDX

- 2 SD

- 3 SD

4411 control rulecontrol rule4411ss control rulecontrol rule

+ 3 SD

+ 2 SD

+ 1 SD

2 SD

- 1 SDX

- 2 SD

- 3 SD

1010 control rulecontrol rule1010xx control rulecontrol rule

+ 3 SD

+ 2 SD

+ 1 SD

2 SD

- 1 SDX

- 2 SD

- 3 SD

METHOD SIGMA QUALITYMETHOD SIGMA QUALITYMETHOD SIGMA QUALITY METHOD SIGMA QUALITY METRICSMETRICS

X = 90 mg/dL ; TEa = 10% ; SD = 3 mg/dL ; %CV = %3.3

Lower Spec limit

ProcessMean

UpperSpec.limitSpec.limit Mean Spec.limit

Three SigmaProcessProcess

3 2 1 1 3σσ σ σ 0 σ 2 σ

81 84 87 90 93 96 99

X = 90 mg/dL ; TEa = 10% ; SD = 1.5 mg/dL ; %CV = %1.7

Lower Spec limit

ProcessMean

UpperSpec.limitSpec.limit Mean Spec.limit

Six SigmaProcessProcess

6σ 5σ 4σ 3σ 2σ 1σ 0 1σ 2σ 3σ 4σ 5σ 6σ

81 82.5 84 85.5 87 88.5 90 91.5 93 94.5 96 97.5 99

Lower Spec limit

ProcessMean

UpperSpec.limitSpec.limit Mean Spec.limit

1.5σ 1.5σshift shift

Six SigmaProcessProcess

6σ 5σ 4σ 3σ 2σ 1σ 0 1σ 2σ 3σ 4σ 5σ 6σ

IncreasingIncreasing PPededIncreasing Increasing PPeded

By Using Narrower Control limitsBy Using Narrower Control limitsBy Using Narrower Control limitsBy Using Narrower Control limitse.g. e.g. 1122SS against against 1133SSB U i M QC M t i lB U i M QC M t i lBy Using More QC MaterialsBy Using More QC Materialse.g. Low, Normal and Highe.g. Low, Normal and HighBy Using Fewer Control DataBy Using Fewer Control Datae ge g 88XX againstagainst 1212XXe.g. e.g. 88XX against against 1212XXBy Using By Using MultirulesMultirulese.g. e.g. 1133SS//2222SS

Recommended Rules For MethodsRecommended Rules For MethodsRecommended Rules For Methods Recommended Rules For Methods with different sigmawith different sigma

Rule(s)NSigma13S26125 12.5S2512.5S or 13S/22S/R4S/41S4413S/2of32SR4S/31S/6x 63

EXTERNAL QUALITY EXTERNAL QUALITY ASSESSMENTASSESSMENTASSESSMENTASSESSMENT

MATRIX EFFECTMATRIX EFFECT

NoncommutableNoncommutable SamplesSamples

EQA organizers often use commercially QC materials specifically prepared to ease transportation and storage, having relatively low cost and exhibits a low vial to vialhaving 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 physicochemicalwhich may have adverse effects on the physicochemical properties of samples8.So, QC materials are frequently are noncommutable with clinical patient sample and they may produceclinical patient sample and they may produce significantly differenent results with different assays.

MATRIX EFFECTMATRIX EFFECT

Commutable SamplesCommutable Samples

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

Matrix EffectMatrix Effect 99thth EQAP HbAEQAP HbA11c Analysisc Analysis

%CVMeannMethod10.46.6580Pars Azmon 10.46.6580Pars Azmon12.05.3227Pishtaz Teb

26.510.81212Biosystem---Roche

8.66.07248NycoCard38.57.75567Total 38.57.75567Total

Matrix EffectMatrix Effect 1111thth EQAP HbAEQAP HbA11c Analysisc Analysis

%CVMeannMethod15.36.0985Pars Azmon 15.36.0985Pars Azmon12.85.4844Pishtaz Teb

21.08.56237Biosystem11.38.2615Roche13.76.33265NycoCard24.57.06646Total 24.57.06646Total

Matrix EffectMatrix Effect 1515thth EQAP HbAEQAP HbA11c Analysisc Analysis

%CVMeannMethod12.58.9035Pars Azmon5.39.0640Pishtaz Teb

11 28 5754Bi t 11.28.5754Biosystem5.69.518Roche5.29.3958NycoCard9.39.01195Total

Matrix EffectMatrix Effect 1717thth EQAP HbAEQAP HbA11c Analysisc Analysis

%CVMeannMethod11 59 4933Pars Azmon 11.59.4933Pars Azmon6.19.6843Pishtaz Teb

10.49.3854Biosystem7.710.3310Roche

12.49.8159NycoCard9 99 61199Total 9.99.61199Total

Matrix EffectMatrix Effect 1818thth EQAP HbAEQAP HbA11c Analysisc Analysis

%CVMeannMethod9 27 1896Pars Azmon 9.27.1896Pars Azmon

10.67.33100Pishtaz Teb

11.97.76229Biosystem4.47.8812Roche8.47.2387NycoCard11 17 49524Total 11.17.49524Total

DATA ANALYSIS FOR DATA ANALYSIS FOR O O S SO O S SINTERPRETATION OF RESULTSINTERPRETATION OF RESULTS

Evaluation of performance of each participant needs Evaluation of performance of each participant needs to establish two values:to establish two values:

11) Assigned (target) value of the test material) Assigned (target) value of the test material22) Acceptable range) Acceptable range

Different methods can be used to establish these Different methods can be used to establish these estimates, but there is no standard protocol estimates, but there is no standard protocol statistical parametersstatistical parametersstatistical parametersstatistical parameters

ESTABLISHING ASSIGNED VALUEESTABLISHING ASSIGNED VALUEESTABLISHING ASSIGNED VALUEESTABLISHING ASSIGNED VALUE

There are three methodsThere are three methods

11) The addition of a known amount or concentration ) The addition of a known amount or concentration ))of of analyteanalyte to a base material containing noneto a base material containing none

22) The use of a Consensus value produced by a group) The use of a Consensus value produced by a group22) The use of a Consensus value produced by a group ) The use of a Consensus value produced by a group of expert or referee laboratories using best possible of expert or referee laboratories using best possible methodsmethods

33) The use of a consensus value produced in each ) The use of a consensus value produced in each round of EQA, and based on the results by round of EQA, and based on the results by participantsparticipantsparticipantsparticipants

ESTABLISHING ASSIGNED VALUEESTABLISHING ASSIGNED VALUEFROM PARTICIPANT RESULTSFROM PARTICIPANT RESULTSFROM PARTICIPANT RESULTS FROM PARTICIPANT RESULTS

assigned value is consensus value (trimmed mean assigned value is consensus value (trimmed mean l ) d i d f ll lt b itt d bl ) d i d f ll lt b itt d bvalue) derived from all results submitted by value) derived from all results submitted by

participants in the scheme of that participants in the scheme of that analyteanalyte

P i l i h h h hP i l i h h h hPractical experiences has shown that the Practical experiences has shown that the consensus value usually agrees closely with the true consensus value usually agrees closely with the true value in schemes with a large number participantsvalue in schemes with a large number participants

Consensus value may not be valid in two conditions:Consensus value may not be valid in two conditions:11) Numbers of laboratories ) Numbers of laboratories is smallis small))22) A large proportion of participants have a significant) A large proportion of participants have a significant

analytical biasanalytical bias

ESTABLISHING ACCEPTABLE RANGEESTABLISHING ACCEPTABLE RANGEESTABLISHING ACCEPTABLE RANGEESTABLISHING ACCEPTABLE RANGE

After calculating method relating consensus value, After calculating method relating consensus value, acceptability criteria must be establishacceptability criteria must be establish

For this, statistical parameters are calculated, For this, statistical parameters are calculated, includingincluding

11) Mean (X)) Mean (X)) ( )) ( )22) Standard Deviation (SD)) Standard Deviation (SD)33) Coefficient of Variation (CV)) Coefficient of Variation (CV)

CV% = SD

Xx 100

X

ESTABLISHING ACCEPTABLE RANGEESTABLISHING ACCEPTABLE RANGEESTABLISHING ACCEPTABLE RANGEESTABLISHING ACCEPTABLE RANGE

Acceptability criteria may beAcceptability criteria may be11) Interval based on group SD (e.g., X ) Interval based on group SD (e.g., X ±± 22SD)SD)22) Fixed percentage (e.g., X ) Fixed percentage (e.g., X ±± constant percent)constant percent)) p g ( g ,) p g ( g , p )p )33) Fixed interval (e.g., X ) Fixed interval (e.g., X ±± constant amount)constant amount)

Alternatively scoring system may be usedAlternatively scoring system may be usedAlternatively, scoring system may be usedAlternatively, scoring system may be used11) ) Bias Index Score (BIS)Bias Index Score (BIS)22) Variance ) Variance Index Score (VISIndex Score (VIS))33) Standard ) Standard Deviation Index or Interval (SDIDeviation Index or Interval (SDI))

Z ScoreZ ScoreZ ScoreZ Score

Z = Xlab - Xpeer

SDSDpeer

BIS =

Xlab - XpeerXpeer x 100SDI =

Xlab - Xpeer

SD BIS = CCV%SDpeer

Chosen Coefficient of VariationChosen Coefficient of Variation(CCV)(CCV)(CCV)(CCV)

CCV are the lowest CVs obtained CCV are the lowest CVs obtained for particular determinations for particular determinations d i fi t t f th EQASd i fi t t f th EQASduring first two years of the EQASduring first two years of the EQAS

It is kept constant so that It is kept constant so that improvements in the performance improvements in the performance

f l b t i b d t t df l b t i b d t t dof laboratories can be detectedof laboratories can be detected

Is Numbers of member in peer group adequate?

No

Is CV% of

Data analysis is not valid

Yes

peer group suitable?

YesNo

What Is the result of data analysis?

UnacceptableWarnningExcellent or Good pg

Need error detection and correction

Follow next EQA ResultNeed no action

Peer GROUP PROGRAMPeer GROUP PROGRAMPeer GROUP PROGRAMPeer GROUP PROGRAMPeer Group Program Is A Combination of Peer Group Program Is A Combination of p gp gInternalInternal And And ExternalExternal Quality ControlQuality ControlWhen EQC Is Used In Conjunction With When EQC Is Used In Conjunction With D il IQC Thi P Will GiD il IQC Thi P Will GiDaily IQC, This Program Will Give Daily IQC, This Program Will Give Laboratories Laboratories Added ConfidenceAdded Confidence in Their in Their Patient Test ResultsPatient Test ResultsPatient Test ResultsPatient Test ResultsAll Labs Use The Same Control Material All Labs Use The Same Control Material and Report Their Results and Report Their Results DailyDailyData Are Analyzed And Reported Data Are Analyzed And Reported MonthlyMonthlyAs As SDISDI and and CVRCVR