Haemoglobin quality control by maintaining levey jennings chart

1. Haemoglobin Quality Control
By: Dr Rashmi Sood
Consultant & Incharge
Department of Transfusion Medicine & Immunohematology
Saket City Hospital , New Delhi
By Maintaining
“LEVEY JENNINGS chart”

2. Pre -do natio n Haemo g lo bin
scre e ning
Pre-donation Hemoglobin screening
Is an important and foremost tests done for blood donor selection.
For blood donation, the minimum acceptable hemoglobin (Hb) is 12.5 g/dl or
haematocrit (Hct) of 38% for both males and females.(1)
This level is set :
1.to ensure that donors have enough blood to give and also have enough iron available
in their bodies to make more blood after they donate.
2. for preventing blood collection from an anaemic donor.
(1)The Indian Drugs and Cosmetics Act, 1940 .

3. .
An appro priate Hb scre e ning
me tho d
Should be available for blood collection
So as to accept as many suitable donors as possible and to prevent
any inappropriate deferrals.
Method for Hb screening should
o Save time
o Be Cost effective
o Be accurate and easily validated for Internal Quality control

4. Various methods of hemoglobin
estimation in Blood
Banks
1.Semi-quantitative gravimetric copper sulfate (CuSO4) method
2.Cyanmethemoglobin spectrophotometric method
3. HemoCue Hb photometer azidemethemoglobin test system - a portable,
battery-operated photometric device for rapid determination of hemoglobin.
4. WHO hemoglobin color scale (HCS) , at places where laboratory based
hemoglobinometry methods are not available.
5. Automated hematology analyzers.

5. Various Hb analysers available in the
market

6. Using Hemocue in the Blood Bank
Calibration: factory calibrated needs no further calibration.
(Against the ICSH-International Council for Standardization
in Haematology Reference Method.)
Quality control: Liquid controls ,Eurotrol Hemotrol
Daily Quality control and Periodic Verification of
the precision and accuracy of the system :
Done as per local guidelines
using manufacturer recommended stabilized control reagents

7. Using Hemocue in the Blood Bank
 These stabilized control reagents (by the name Eurotrol Hemotrol) are
produced in three physiologically relevant levels-
Low (7.8-8.2gm/dl),Normal(11.8-12.2gm/dl)and
High(15.8-16.2gm/dl).
Results were recorded in separate laboratory registers
and subsequently transcribed into the LJ charts.

8. QUALITY ASSURANCE & QUALITY
CONTROL
 Quality Assurance is process oriented and focuses on
defect prevention.
 It is a set of activities for ensuring quality in the processes
by which products are developed.
 Quality control is product oriented and focuses on
defect identification.
 It is a set of activities for ensuring quality in products ,the
activities focussing on identifying defects in the techniques of
producing products .

9. INTERNAL QUALITY CONTROL &
EXTERNAL QUALITY CONTROL
 IQC is used on daily basis
 IQC helps to decide whether to accept or reject results of patient
samples
 IQC refers to the process of minimizing analytical(Testing)
errors related to operational techniques and activities.

10. EXTERNAL QUALITY CONTROL
 EQC – comparison of quality between the laboratories.
 EQC confirms results of IQC.

11. INTERNAL QUALITY CONTROL
in Hb measurement
Internal Quality control data for Hb measurement is most easily visualized using Levey Jennings (LJ)
Chart
A visual indication of the Internal Quality
Dates of analyses plotted along the X-axis and control values plotted on the Y-axis.
Mean and one, two, and three standard deviation limits are also marked on the Y-axis.
Distance from the mean is measured in standard deviations.

12. Levey Jennings (LJ)Charts
 Named after S. Levey and E. R. Jennings who in 1950 suggested
the use of Shewart’s individual control chart in the clinical
laboratory .
 LJ charts plot daily QC values .

13. Westgard Rules for Evaluation
of LJ charts for QC
Westgard rules are applied to
Interpret daily QC values on the LJ charts
 whether the results are in -control or not
 whether they can be released, or need to be rerun.
Indicate the type of laboratory error
the pattern of plotted points is noted
to detect random errors and shifts or trends of the performance
in Hb measurement .
(Ref :Grant, E.L. and R.S. Leavenworth (1988). "Statistical Quality Control", Sixth Edition,
McGraw-Hill Book Company.)

14. Application of LJ charts for QC
 Stable control material/s which mimics patients sample
are analyzed (day to day) by plotting a mark daily on
the control chart(Levey Jennings Chart).
 Evaluation whether measurements is in control done
using Westgard multi–rules.
 The distance from the mean is measured in standard
deviations (SD).
 Lines run across the graph at the mean, as well as one,
two or three standard deviations on either side of the
mean.

15. Calculation of Control Limits
 Standard deviation calculated from the following
equations:

16. Errors

17. Westgard rules
 Formulation of Westgard rules is based on statistical
methods.
 Westgard rules are used to detect both random and
systematic errors.
 Can be programmed on to automated analyzers .
 Careful application to prevent false rejections.

18. Application of the Rules
 The 12s rule is used as a warning rule and prompts a more
detailed inspection of the data using the other control rules.
 If neither control observation exceeds a 2s limit, the analytical
run is in-control and patients’ data may be reported.
 If either observation exceeds a 2s limit, the control data are
tested by applying the13s, 22s, R4s,41s, and 10x rules.
 If none of these rules is violated, the run is in-control.
 If any one of them is violated, the run is out-of-control.

19. Westgard rules -Control Rules
(Decision Criteria)
 12s- the control rule where one control observation exceeds
control limits set as x ± 2s.
 The warning rule for a Shewhart chart and is interpreted
as a requirement for additional inspection of the control data.
 13s - the control rule when one control observation exceeds
control limits set as x ± 3s.
 Run is rejected.

20. Westgard rules-Control Rules
(Decision Criteria)
 22s - is the control rule when two consecutive
control observations on same control or two
observations within a run, one on each of two
different control materials, exceed the same
limit, which is either x + 2s or x - 2s.
 the run is rejected

21. Westgard rules-Control Rules (Decision
Criteria)
 R4s control rule
 when the range or difference between the two
control observations within the run exceeds 4s.
 run is rejected

22. Westgard rules-Control Rules (Decision
Criteria)
 41s control rule
 when four consecutive control observations exceed the
same limit, which is either x + 1s or x - 1s.
 the run is rejected

23. Westgard rul e s - C o n t r ol Rules (Decision
 10x control rule
Criteria)
 the run is rejected when 10 consecutive observations fall on the
same side of the mean (x).
 These consecutive observations can occur within one control
material or across control materials. This would require
inspection of 10 or five consecutive runs, respectively.

24. Applying the control rules -Random and
Systematic Errors
Type of errors:
(i) Random errors (affect precision) – Usually 13s and R 4s
errors
These errors can either be positive or negative.
Their direction and exact magnitude cannot be predicted.
Usually are due to error in Techniques.

25. Applying the control rules -Random and
Systematic Errors
(ii) Systematic errors (affect accuracy) – Usually 22s, 41s and 10x errors
/or Inaccuracy
They are always in one direction.
They displace the mean of the distribution from its original value.
When the change in the mean is gradual, it is demonstrated as trend in
control values .
 When the change is abrupt, it is demonstrated as shift in the control
values.
Cause all the test results to be either high or low.
Usually due to change in testing process.

26. Random and Systematic Errors

27. Level of QC applied in a laboratory
 The level of QC (Low, Normal, High) applied varies according to the
number of specimens analyzed per day.
 The following protocol may be adopted according to the total number of
specimens analysed :
 Less than 40 per day - apply at least one level (Low,Normal,High) QC
once a day.
 Between 40-80 per day - apply two level QC at least once a day.
 More than 80 per day - apply two level QC at least twice a day.

28. Material & Methods of the study
A prospective study at our centre.
Over a period of 1 year1 month.
Hemo –Controls (Eurotrol): Low Control (7.8 to 8.2gm/dl ) High
Control ( 15.8 to 16.2 gm/dl ) Normal Control ( 11.8 to 12.2
gm/dl) were run in the Hemocue machine daily and Levey –
Jennings chart were maintained .

29. Results
 Study was carried out from July 2013 to Aug 2014
Deviation observed in low QC – control value no 07 in Jan14
Deviation observed in normal QC- control value13 in Jan14
Deviation observed in high QC- control value 14 in Feb14
 1 Standard Deviation
 Deviation sorted out after re testing.
 They disappeared on retesting.
 Change of the staff doing the test was the reason found for these
random errors .

30. Corrective Actions
 For responding to out-of control situations , guidelines should be established and
properly implemented.
 Withhold patients’ results till the out of control situation is sorted out
 Identify the cause of the problem
 Avoid false rejections.
 Start with checking the simplest and most frequent faults and continue further
depending on the method and the equipment involved.
 It is essential to determine the type of error (random or systematic) in order to
specifically correct the problem.
 (i) Random errors (affect precision) – Usually 13s and R 4s errors
 (ii) Systematic errors (affect accuracy) – Usually 22s, 41s and 10x errors

31. Common causes of erroneous results
Control material viscid as was in the refrigerator
Insufficient mixing of the samples
Presence of air bubbles in the cuvette
Excess blood on the back of the cuvettes, due to over filling
Reading the results too soon or too late (beyond 10 minutes)
Filling from the optical eye rather than the filling end

32. Remedy
 Bring controls to room temp before testing
 Check control storage conditions
 Check control expiry date/contamination
 Mix samples adequately
 Adequate training on the technique of proper filling the cuvettes to
avoid air bubbles and over filling

33. Remedy
 Reading result after few seconds of filling the cuvette
 Repeat QC from the same vial or fresh vial taken out
from the refrigerator or from a fresh QC lot
 Relate causes to any recent changes

34. Conclusions
Quality control data is most easily visualized using a
Levey Jennings chart.
We suggest, all blood banks to maintain L-J chart as a
Quality Indicator to validate the working of the Hemocue.

35. References
 Ref:
 1. Hemocue Hb 201+ Operating Manual, Page 20-21
 2.Grant, E.L. and R.S. Leavenworth (1988). "Statistical
Quality Control", Sixth Edition, McGraw-Hill Book Company
 3.GUIDELINES FOR GOOD CLINICAL LABORATORY PRACTICES (GCLP)
Indian Council of Medical Research New Delhi 2008
 4.Westgard, J.O, P.L. Barry, and M.R. Hunt (1981). "A Multi-rule
Shewhart Chart for Quality Control in Clinical Chemistry, “Clinical
Chemistry, vol. 27, pp. 493-501