A presentation in the Annual meeting of the Egyptian American Scholars (AEAS) in Cairo 2015. I am trying here to describe, in short, from my point of view as a laboratorian, the points that we need to discuss with clinicians. Both groups should share some terms and definitions and should see things from the same perspective!

1. What do clinicians need from a
laboratory test?
Ola H. Elgaddar
MD, PhD, MBA, CPHQ, LSSGB
Lecturer of Chemical Pathology
Medical Research Institute
Alexandria University
Ola.elgaddar@alexu.edu.eg

7. Does it
have the
right
tests??
Is he a
patient??
Is it
correct??

8. In this context,
what is meant by:
ØDoes the lab request have the “right”
tests??
ØIs this person a “patient”??
Diagnostic (Clinical) Performance

9. ØIs it a “Correct” Result??
- Accredited lab (ISO 15189 – CAP – JCI)
- Quality Management System (QMS)
Pre-analytical
Analytical
Post-analytical
- Errors
- Uncertainty
Analytical Performance

10. There are two arms for lab test
performance, and both should be equally
considered:
ØAnalytical Performance
ØDiagnostic Performance

11. Analytical
Performance

12. Quality
Doing the right thing right, from the
first time and every time!

13. Accreditation
An institution or a program meets
standards of quality set forth by an
accrediting agency

15. In a medical lab, there are 3 main stages:
1) Pre-analytical
2) Analytical
3) Post-analytical
All of them should be under tight control

17. 1) Pre-analytical
• Patient & specimen identification
• Patient preparation
• Specimen collection, transport and handling
• Monitoring personnel

19. 2) Analytical
The 5 Ms???
qMachine (Technology)
qMethod (Selection / Evaluation)
qMaterial (Reagents)
qMan Power (Training)
qMeasurement (IQC & EQC)

20. 3) Post - Analytical
ØTranscriptional errors
ØMissed flags
LIS is a radical solution
Almost!!!

21. Evaluation of a
Laboratory
Method

22. Validation / Verification??
Method validation: (Manufacturer)
Establishing the performance of a new
diagnostic tool
Confirmation, through the provision of
objective evidence, that the requirements for
a specific intended use or application have
been fulfilled’ (doing correct test)......
ISO 9001:2005

23. Validation / Verification??
Method verification: (Lab / User)
A process to determine performance
characteristics before a test system is utilized
for patient testing.
Confirmation, through the provision of
objective evidence, that specified
requirements have been fulfilled’ (doing test
correctly)……ISO 9001:2005

24. The following items need verification
ØAnalytical Specificity: Interference studies
ØAnalytical Sensitivity: Calibration curve
Detection limit
ØReportable range: Linearity experiment
ØPrecision: Replication study
ØAccuracy: Bias / Recovery study
ØReference Intervals

25. Analytical Specificity
The ability of an analytical method to detect
“ONLY” the analyte of interest.
Freedom from interference by any element
or compound other than the analyte of
interest

28. Analytical Sensitivity
- The ability of an analytical method to
detect a low concentration of a given
substance in a biological sample. The lower
the detectable concentration, the greater
the analytical sensitivity.
- Detection limits studies

29. ??

30. Reportable Range
=
Analytical Measurement Range
It is the range of numeric results a method
can produce without any special specimen
pre-treatment, such as dilution.

31. Precision
Closeness of agreement between quantity
values obtained by replicate measurements
of a quantity, under specified conditions.

32. Accuracy
Closeness of the agreement between the
result of a measurement and a true value of
the measurand.

34. Reference intervals
ØEach lab should establish its own
reference intervals regarding the population
that it serves.
ØReference ranges differ by age, sex and
ethnic group.
ØThe lab should report the appropriate
reference range with each released result,
otherwise, the clinician will not be able to
interpret the result.

35. Reference intervals
Example:
TSH of an infant (1 month old) is 5uU/mL
If the lab reports the reference range of
adults with the result (0.4 – 4), this result
would be abnormal!
If the correct reference range for age was
reported (1 – 7.9), this result is completely
normal.

36. Internal Quality Control (IQC) is used, on daily
basis, in the decision to accept or reject
results of patients samples and enables the
lab to describe and monitor the quality of its
work.
-Usually it has 2 levels (Sometimes 3);
representing the “Normal” and the
“Pathological” analyte level.

37. External Quality Control (EQC) =
Proficiency test is used, on monthly or Bi-
weekly (Or others) basis, where labs from all
over the world join the program and send their
used Method / Analyzer.
- A statistical comparison is made and each
lab result is compared to the result of its peer
group in each analyte.

38. Types of Laboratory errors
Ø Random error, RE, or imprecision is
described as an error that can be either
positive or negative, whose direction and
exact magnitude cannot be predicted,
where the distribution of results when
replicate measurements are made on a
single specimen.
ØUsually, due to error in Pipetting

39. Types of Laboratory errors
Ø Systematic error, SE, or inaccuracy is an
error that is always in one direction,
displacing the mean of the distribution from
its original value.
ØIn contrast to random errors, systematic
errors are in one direction and cause all the
test results to be either high or low.
ØEither constant or proportionate
ØUsually, due to error in calibration

40. Uncertainty
Ø It is an interval around a reported
laboratory result that specifies the location of
the true value with a given probability
Ø It takes into consideration both the
imprecision (SD), and the inaccuracy (Bias)
Ø Should be reported to the clinician, or at
least be available upon request!
ØExample: Lab XYZ reports blood glucose
level with 6 % uncertainty
(i.e: Result +/- 6%)

41. Diagnostic
(Clinical)
Performance

42. Clinical utility of a lab test refers to its ability
to differentiate between diseased and non-
diseased persons.

45. The ideal tests has both diagnostic
sensitivity and specificity equal 100 %
But actually, no test is ideal!!
When sensitivity increases, specificity
decreases and vice versa.

46. Depending on the clinical utility, the
appropriate test is selected; if we are
screening population, then we need a test of
high sensitivity (You do not want to miss a
single case, even if you got false positive
cases).
Ex: Occult blood in stool as a screening tool
for cancer colon

47. SUMMARY
Ø The clinician should know the Clinical
performance of each test before ordering it;
bad test selection gives a bad result that is
not useful in the diagnosis.
Ø The lab doctor should measure the
Analytical performance of lab tests, should
ensure its validity and should provide such
data to the clinician

49. THANK
YOU