1. Many lab professionals think Quality in a Medical Laboratory is ….
Accurate
Timely
Reliable
Reproducible
RESULTS

2. INSTITUTE OF BIOCHEMISTRY WELCOMES YOU ALL TO THE CMEON
“QUALITY ASSURANCE IN CLINICAL LABORATORY
UP, CLOSE & PERSONAL”

3. 8 rights make Quality in a Medical Laboratory is ….
Choosing the Right test
Collecting Right Specimen
After Right patient preparation
Testing by the Right method
Reporting the Right based on
Right Reference intervals at the
Right time and at the
Right Price

4. Where can you go wrong in a lab ?

5. Quality is ….
A subjective term - for which each person has his / her own definition
Technically Quality can have two meanings
A product or service that fulfills the defined and expected requirement
stated and implied needs
A service or product free from defects & deficiencies

6. Stages of Quality - Hierarchy
MANAGEMENT
QUALITY SYSTEM
QUALITY ASSURANCE
QUALITY CONTROL

7. WHO definition of QA & QC is ….
QA - Includes Internal QC, External QA, pre-analytic phase, test standardization, post-analytic phase, management, and organization (WHO, 1992)
QC - Internal quality control (IQC) – set of procedures for continuously assessing laboratory work and the emergent results; immediate effect, should actually control release of results (WHO, 1981)

8. Quality Assurance & Quality Control - difference is ….
QA is for correction & prevention of errors or defects in the entire lab
QC is detection of errors and defects in testing process

9. Purpose of Internal & External QC
Internal QC
For CONTINUOUS & IMMEDIATE (DAILY) monitoring of the laboratory work and the emergent results in order to decide whether the results are reliable enough to be released to physicians (WHO, 1981)
Measures Precision & Repeatability of the systems & methods in use in the lab.
Illusion of ‘short term accuracy’ of the lab results.
Do not detect the accuracy or trueness of patient results over a ‘longer term’

10. Purpose of Internal & External QC
For PERIODIC AND RETROSPECTIVE monitoring of lab results by an independent external agency to indicate to the laboratory and its staff the accuracy or bias in their systems & methods
Lab can know its shortcomings and change their Internal Quality Assurance procedures.

11. Why EQAS is necessary?
Serves as an educational tool and help to monitor & improve the performance of the lab
Measures the accuracy or bias of its results and stability of methods – Over a longer period of time in terms of years
Mandatory requirement for applicant & accredited labs
Non participation or repeated failures in an EQAS or PT programme may result in temporary suspension or cancellation of accreditation for those non EQAS tests
Gives the laboratories, both the management & technical staff, added confidence in their patient test results

12. WHAT DOES IT IDENTIFY ?
Identifies systematic kit & reagent problems, water quality problems, analyte calibration stability and status, equipment performance
Indicator of where to direct improvement efforts
Identifies training needs of lab personnel
Benchmarks the lab’s performance against others
Early Warnings System for Problems

13. HOW SHOULD IT BE USED ?
Should only be used for motivating staff & not to punish them
Inaccurate lab results are not due to technicians
But due to failure of lab systems

14. HOW SHOULD IT BE USED ?
EQAS / PT samples should be treated exactly as the patient samples Only then the correct situation in the lab can be found fixing the problem becomes easy
Never
Run the calibration on the day of reporting EQAS sample if it is not a scheduled /required calibration
Repeat the EQAS samples where as the patient samples are tested only once and give the mean of multiple runs
Ask a specific analyst run the EQAS / PT sample

15. REMEMBER EQAS …. SUPPLEMENTS Internal Quality Control
NEVER a SUBSTITUTE for Internal QC
Both measure 2 different aspects of quality

16. INTERPRETATION OF EQAS REPORTS
VIS – Variance Index Score
SDI –Standard Deviation Index
Z-Score – Classical & Robust

17. Variance Index Score
First proposed by the United Kingdom National Quality Control Scheme (UKNEQUAS)
CCV (Chosen Co-efficient of Variation) & DV (Designated Value) used to calculate VIS
CCV is just the Allowable Limit of Error for an analyte (TEa) - Sum of both imprecision and bias
Set & recommended by WHO after studying the performance of many Indian labs

18. CCV of some common Analytes
Glucose
 7.5
Sodium
2.3
Urea 10
Potassium
5.0
Creatinine
Chloride
6.0 CK
7.3
AST
12.5
T.Bilirubin
19.2
ALT
17.3
T.Protein
7.5
ALP
15.5
Albumin
Amylase
Calcium
LDH
Uric acid
7.7
Phosphorus
7.8
Cholesterol
Bicarbonate
9.0
TGL 14
HDL- C
7.6
HDL
Iron 15

19. Calculation of VIS Designated Value [DV] = 120 mg %
Participant's result          =   mg%
    % Variation [%V]    = Participant's Result - Designated value   
X 100                                                      Designated value
                                         X  100   =     25    X 100                                   120                              120   
                                         
=            20.8
Variance Index        =         %V     X   100    =  20.8     X    100   =   277                                     CCV                       7.5
VIS = 277

20. How to read the EQAS results ?
Calculation of VIS
How to read the EQAS results ?
Check the VIS & OMVIS values for each parameter every month
Check if your value is close to DV
Closer it is lower will be your VIS & better is your lab’s accuracy
Remember If your VIS is < 50 it is regarded and given as zero score
Even if >400, it is still given as 400 only

21. Interpretation of VIS VIS Performance < 100 Very good 100 -150 good
satisfactory room for improvement
> Not acceptable
If VIS of >200 on two or more occasions for the same analyte, them check your standardization procedures & calibration
Indicates an accuracy problem (systematic error / bias )

22. Interpretation of VIS
Check the monthly OMVIS.(Overall Mean VIS) cumulative performance over a period  
OMVIS Performance
< Very good - your result are very close to DV
Need to take care of those parameters for which the reported values are very different from the  DV for that particular method
> You are probably reporting many wrong results & you should take urgent steps to locate the problem and correct them

23. Calculation of VIS – Method Mean
The ‘Method Mean' - Mean obtained from results of all participating labs following the same method including results of outliers
The ‘Designated Value’ is the value obtained after excluding results, from labs with same method, which are > 3SD of Method Mean and recalculating the mean after eliminating the outliers - Mean of ‘inliers only’
The 'Reference Mean' - Mean obtained at the organizing lab  after exposing the QC samples to ambient temperature (25-35 C) for a period of 7- days (transport time) and analysing them on five different days
The reference mean is shown  against the method by which it was analysed in the organizing lab
Calculation of VIS – Method Mean

24. Mean value obtained at the Reference Lab (CMC) after exposing 5 vials to ambient Temp. for 9 days and analyzing them on 5 diff. days

25. Mean value obtained at the Reference Lab (CMC) after exposing 5 vials to ambient Temp. for 9 days and analyzing them on 5 diff. days

26. Mean value of results from of all participating labs with same method

27. Value given (DV) is the mean of all participating labs for that method after excluding results from labs outside 3SD of the Mean Value (of the participating labs with the same method)

28. STANDARD DEVIATION INDEX
Another Statistical tool – assigned to the lab by the EQAS / PT provider on the performance of the lab for each analyte in a EQAS cycle
A measure of relative inaccuracy / relative bias

29. What is normal or Gaussian distribution ?
Out of 100 results
68.2% of values fall within ± 1SD
95.5% of values fall within ± 2SD
99.7% of values fall within ± 3SD

30. IS KNOWING SDI USEFUL ?
Yes - A measure of the result around a mean among a group of values
Since 95 % of all results in a normal population fall within ± 2 SDs of the mean, +2 SD is considered an acceptable laboratory value
Expressed in the units being measured

31. IS KNOWING SDI USEFUL ? Simply said
The number of Standard Deviations that your lab’s mean differs from the Peer Group Mean
. Difference is converted into SD units (SDI)
The SDI indicates how large / small the difference is between your result and target value
Simply said
‘Difference between your result and group mean in terms of the number of standard deviations from the overall mean’

32. IS KNOWING SDI USEFUL ?
Actual magnitude of the difference in the units of the test may look too small or too large
To figure the actual size of this inaccuracy / bias in concentration units, you need to multiply by the actual SDI by of the group SD.
For e.g if the group mean is 102 mg/dL for TGL and group SD is 5 mg/dL and your SDI score is 1.2
Actual quantitative difference is 1.2 x 5 = 6 mg/dL

33. IS KNOWING SDI USEFUL ?
Any SDI of 2.0 or greater in a EQAS cycle for any analyte deserves special concern – indicates some for of systematic error
Any test whose average SDI is 1.0 or greater deserves some special attention because your method shows a systematic difference from the group.
Likely to lead to unacceptable results in future
SDI up to 1.0 – your performance is satisfactory – your result is with 1 SD of the group – you are with in the 68.7 % of lab’s result whose values are close to mean

34. IS KNOWING SDI USEFUL ?
if you observe SDIs such as -0.4, -0.2, , and -1.0 (all negative) for an analyte in successive cycles, your method is generally running on the low side and is negatively biased, on average, by +0.6 SDI
You are reporting precise pateint values but lower than the true value by 0.6 SD ()
So better
calibrate your instrument and analyte
or requires instrument maintenance

35. Z-Score Classical Z Score – same as SDI
Can be used for internal quality control also

36. Z-Score
Robust Z score statistic is used when the distribution of results of participating labs is not Gaussian (not ‘normally’ distributed) and there are varied results / outliers
Both accuracy and precision (repeatability as well as reproducibility) are assessed in terms of robust Z score - both within and between labs Z score (ZB & ZW)
The participant labs are asked to analyse the same sample TWICE and submit both results to the EQAS provider

37. Z-Score

38. Z-Score
Robust Z score =
Normalised Lab’s result- Median result of all labs )
Normalized IQR ( Inter Quartile Range)
It is calculated based on the “median” value (central value) and the ‘interquartile range’
All results from participating labs are arranged in an ascending manner (lowest to highest) the central value is taken as the median
The 25th and 75th percentile values are calculated The ‘interquartile range is the difference between the 75th & 25th percentile
The 25th quartile (Q1) is the value below which a quarter of the results lie. Similarly, the 75th quartile (Q3) is the value above which a quarter of the results lie.
IQR = Q3 - Q1
Normalized inter quartile range (NIQR): NIQR = IQR x (a constant)

39. Z-Score The between laboratory Z-score (ZB) =
(S - median ) / (IQR x )
S = (A + B)/[square root of (2)] = standardised sum of the two results for a laboratory (where A and B are results of two samples of the same test). Within laboratory Z-score (ZW) =
(D- median / (IQR X ) D = (A - B)/[square root of (2)] = standardized difference between the two results for a laboratory While testing two specimens in an EQAS / PT programme by a lab performance both ZW and ZB should be considered simultaneously for assessing the performance

40. Z-Score
Interpretation of Robust Z-scores: Z score less than 2 - Satisfactory Z score 2 but less than 3 - Questionable perfromance Z score more than 3 – Unsatisfactory
Both ZB & ZW should be < 2
Using only one Z-score may misleading
ZW < 2 ZB > 2 = Higher bias i.e low reproducibility
ZB < 2 ZW > 2 = low precision (i.e., low repeatability)
For assessing laboratory's technical competency, both ZW and ZB value should be low at the same time.

41. EXERCISES ON INTERPRETATION OF EQAS REPORTS Dr.V.K.Ramadesikan

42. Why Analysis of EQAS reports is important ?
True benefit of EQAS /PT proficiency testing, lies in carefully & critically evaluating your results and report
Proper analysis of EQAS testing results can reveal problems even before failure in EQAS or even an adverse patient result
Potential problems can be recognised by recognising patterns from graphs
Review both the present cycle results as well as performance from previous cycle for the same analyte
Graphs of Z score or SDI or VIS or % deviation for trends
Otherwise trends will be missed

43. How to recognise problems ?
Results may consistently be different from the target peer group mean - All results on one side of the mean (may be close to mean or at variable distances from mean) – Systematic Error
Majority of results are close to the target value but some show larger deviation s on one side or both side of mean – Random Error
Reasons and hence corrective action differs

44. How to recognise problems ?
Random error is an error / mistake / inaccuracy that has no set pattern. Its occurrence cannot be predicted
Results on an average are close to target mean. Few results show large deviations on either side of target
Detected by sudden, undue % deviation /SDI /Z Score – > 3.5
Indicates lab’s imprecision / poor reproducibility
Easily identified – values are far beyond the usual – e.g SDI from 1.5 to 4.0 – 6.0

45. How to recognise problems ?
Systematic error – set pattern of error / mistake. Its occurrence can be explained and corrected
Constant difference between the participant lab’s value and group mean All results lie on one side of mean
Indicates lab’s bias or inaccuracy but good precision
A progressive increase in deviation on the same side – ‘ shift’ or stabilizes after a gradual increase ‘trends in

46. Sources of Random Errors
Random errors are blunders
Transcription errors – result not correctly transcribed from the instrument to workbook or PT sheet or from the Workbook to the system
Misplaced decimal points e.g serum potassium 58.2 instead of 5.82
Result was entered in the wrong instrument or method group on the result form of PT provider.
Lab might have changed the method or instrument recently but not updated with PT provider

47. Sources of Random Errors
Mislabeling errors, interchanging results of PT specimens, misplacing specimens in analyser rack, inappropriate reagents and standards
Result of some other analyte entered in the PT form of the provider in the system
Wrong units. Result in one unit in the instrument but not converted to unit of EQAS provider e.g ug /mL instead of ng/L , mg/dL instead of g/L
Result found on evaluation report from PT provider not matching with the result on the report form mistake of PT provider
Calculation errors (conversion from one unit to another)

48. Sources of Systematic Errors
Recalibration if not done earlier – esp if a new lot of reagent has been used or if the open vial stability of the reagent is doubtful
Instrument maintenance – major part needs servicing or replacement (optics, alignment, incubation temperature failure, Internal QC values having a bias
Recent instrument malfunction, instrument failure soon after PT specimen testing
Assay settings (sample volume, reagent volume, delay time incubation time no of readings to be taken etc. )
improper reconstitution of QC materials, water quality, not following manufacturer’s / PT provider’s instructions while reconstituting, storing or handling reagents / QC materials

49. What type of Error is indicated in green and red ?

50. Systematic Error

51. SAMPLE EQAS MONTHLY REPORT
Your result

52. SAMPLE EQAS MONTHLY REPORT

53. SAMPLE EQAS END OF CYCLE REPORT

54. SAMPLE EQAS END OF CYCLE REPORT

56. SAMPLE CAP EQAS REPORT

57. SAMPLE CAP EQAS REPORT

58. SAMPLE CAP EQAS REPORT

59. Misplacing of specimens or interchanging results of PT specimens
SAMPLE EQAS REPORT
Transcription error
Misplacing of specimens or interchanging results of PT specimens
U 1
31.3
909.51 U3
U 2
13.1
28.31 U1
U 3
1031.9
14.8 U2

60. ALT – 226 U/L
Mean – 445
Result
Mean – 445
SDI – 4.34
SDI – 4.34

61. Analytical error – Calculation error PT was repeated with 1 in 2 dilution as results were high but the result was not multiplied by 2 Diluted result was sent

62. SAMPLE EQAS REPORT

63. SAMPLE EQAS REPORT Erratic Results – Very poor precision and accuracy
Problem – Internal Controls wide SD due to various reasons –
Instrument not maintained & calibrated reagents problems deterioration
Analyte not calibrated
Procedural problems

64. SAMPLE CAP EQAS REPORT

65. SAMPLE EQAS REPORT
1. Systemic error may have seeped in the system anytime after the last EQAS sample reporting – look at daily controls for any shift in values
2. May be a random error – Keep a watch on daily controls and follow during next EQAS
3. Wrong sample was tested
4. Wrong preanalytical stage – reconstitution, storage etc – look at values of other analytes
Are they with in acceptable limits of SDI and in the same direction ?

66. SAMPLE CAP EQAS REPORT

67. SAMPLE EQAS REPORT
Systematic error – one showing a positive bias and other a negative bias
Needs
Recalibration for analyte
Instrument maintenance
Internal QC Value Mean needs to be reset

68. SAMPLE EQAS REPORT

69. SAMPLE EQAS REPORT
Fairly a good performance in terms of accuracy and precision
Values on either side of mean No Bias
Values within =/- 0.5 SD