Transcript Analytical variability

Analytical & pre-analytical variability
FibroTest and FibroMax
FT in diagnostic of HBV
In this presentation
Pre-analytical variability
1.
Fasting versus non-fasting
2.
Transport, pre treatment and storage
3.
USA specifications for FibroSure (USA trade mark for FibroTest)
Analytical variability
4.
Inter-laboratory variability
5.
Intra-laboratory variability
6.
Transferability between analyzers
FT in diagnostic of HBV
Pre-analytical variability
Fasting, Storage, US specifications
FT in diagnostic of HBV
Fasting versus non fasting
Munteanu et al, Comp Hep 2004
• Intra-individual fasting versus postprandial variation of biochemical
markers of liver fibrosis (FibroTest, FT) and (ActiTest, AT)
Patients and
methods
Results
 64 subjects
 Measurement of variation +/- 1 hour from meal
 No significant impact on FT/AT components
 ANOVA >0.09 and coefficient of variation (CV) from 0,09 for FT to 0,13 for AT
 Spearman correlation coefficient from 0,87 to 0,995
 Significant impact on triglycerides and glucose
 ANOVA P=0.01, CV= 0.65 and ANOVA P=0.04, CV=0.31
 Concordance between fasting and predicted histological stages and grades
 FT: kappa=0.91, AT: kappa=0.80  almost perfect
Conclusion
For FibroTest: Fasting is not a requirement for to perform FibroTest, which make the
screening for patients at risk of liver diseases more convenient
For FibroMax: Due metabolic components of the test, fasting is required to perform a
valid FibroMax (especially NashTest and SteatoTest
FT in diagnostic of HBV
Transport, pre treatment and storage
- Messous et al, Clinica Chimica 2005
• Time impact of serum storage temperature on stability of important liver
enzymes and proteins and on FibroTest-ActiTest
Conclusions
FibroTest
 ActiTest results diminish more than
fifty percent with -20°C and -35°C
storage.
 Sera storage at –80°C is
recommended for retrospective
analyses.
ActiTest
FT in diagnostic of HBV
 To avoid the risk of false negative or
false positive results for non-invasive
liver markers like FibroTest-ActiTest,
we recommend validation studies on
fresh sera.
USA specifications for FibroSure
(USA trade mark for FibroTest)
FIBROSURE™ 550123
CPT
 Pending
Synonyms
 HCV FIBROSURE™; FIBROSURE™, FibroTest, ActiTest
Test Includes
 FibroTest (alpha2-macroglobulin, haptoglobin, apolipoprotein A1, bilirubin, gamma
glutamyl transpeptidase [GGT]);
 ActiTest (alpha2-macroglobulin, haptoglobin, apolipoprotein A1, bilirubin, gamma
glutamyl transpeptidase [GGT], alanin aminotransferases [ALT])
Specimen Serum
 Volume 4 mL
 Minimum Volume 2 mL
 (Note: This volume does not allow for repeat testing.)
Container
 Red-stopper tube or serum-separator tube
Collection
 Separate serum and refrigerate at 2°C to 8°C. Specimen is stable for as long as three days.
Freeze if
 Storage longer than 72 hours is needed.
Storage Instructions
 Refrigerate –80°C
FT in diagnostic of HBV
USA specifications for FibroSure
(USA trade mark for FibroTest)
Reference Interval
METAVIR scale
Fibrosis stage
F0: no fibrosis
F1: portal fibrosis
F2: bridging fibrosis with few septa
F3: bridging fibrosis with many septa
F4: cirrhosis
Necroinflammatory activity grade
A0: no activity
A1: minimal activity
A2: moderate activity
A3: severe activity
Use noninvasive
measure
 of fibrosis and necroinflammatory activity in the liver of individuals with
chronic hepatitis C virus
Limitations
 Because this procedure is new, Medicare and other carriers may not yet
recognize it as a covered benefit for patients.
Methodology
 Patented Artificial Intelligence algorithm combines patient’s age, gender, and
the results of six biomarkers to generate a measure of fibrosis and
necroinflammatory activity in the liver
FT in diagnostic of HBV
Analytical variability
Fasting, Storage, US specifications
FT in diagnostic of HBV
Inter-laboratory Variablity
Halfon et al, Comp Hep 2002
• A prospective assessment of the inter-laboratory variability of biochemical
markers of fibrosis (FibroTest) and activity (ActiTest) in patients with
chronic liver disease
Concordance (kappa coefficient) between laboratories and the reference center.
FibroTest calculated with GGT expressed in International Unit
ActiTest calculated with GGT-ALT, expressed in International Units
Conclusions
 Standardized methods against a reference method , as well as calibrated analyzers should be used to increase
inter-laboratory coherence, particularly for GGT and ALT measurements.
 ALT and GGT expressed as multiples of the upper limit of normal should be avoided.
FT in diagnostic of HBV
Intra-laboratory variabilty
- Imbert-Bismut et al, Clin Chem Lab Med 2004
• Intra-laboratory analytical variability of biochemical markers of fibrosis
(FibroTest) and activity (ActiTest) and reference ranges in healthy blood
donors.
Total imprecision for FT-AT and its components on pooled sera (NCCLS-EP5-T)
 The total imprecision is correct for the different parameters.
 A VC of 8.8% for total bilirubin was acceptable considering that this variation occurred for the low mean values
(mean 7.5 micromoles/L).
FT in diagnostic of HBV
Intra-laboratory variabilty
- Imbert-Bismut et al, Clin Chem Lab Med 2004
Intra-patient reproducibility of components and of FibroTest-ActiTest
 Concordance between two consecutive measurements was strong (kappa=0.88) for cirrhosis (F4)
versus non-cirrhosis.
 Stages F0/F1, F2 and F3F4 had kappa coefficients of 0.83 and the concordance was moderate for
the repeated ActiTests (kappa=0.44)
FT in diagnostic of HBV
Intra-laboratory variabilty
- Imbert-Bismut et al, Clin Chem Lab Med 2004
Conclusions
 The reproducibility of two FibroTests in the same patient evaluated four days apart is good despite
some isolated variations of the components. This however, has no impact due to the linearization
of the results.
 The homogeneity of the results could be attributed to the homogeneity of adapted techniques on
the different analyzers (standardized techniques compared to reference techniques), as well as the
same conditions of calibration of the enzymatic activity measurements.
 The study demonstrated the analytical reliability of FibroTest and ActiTest and the importance of
the continued development of homogeneity and good transferability of the results between
analyzers and laboratories.
FT in diagnostic of HBV
Transferability between analysers
- Imbert-Bismut et al, Ann Biol Clin 2005
• Results transferability on RXL, ARX, X-Pand, BN2 (Dade Behring) and
modular DP (Roche Diagnostics) analyzers: application to component
assays of FibroTest and ActiTest (on 150 serum samples)
Methods of measurement adapted on different automates and evaluation methods
FT in diagnostic of HBV
Transferability between analysers
- Imbert-Bismut et al, Ann Biol Clin 2005
Results of inter-platform comparisons of Dade Behring: RXL, ARX, X-Pand and results of
BN2-Modular / RXL: regression models according to Passing- Bablok.
Conclusions
 This study showed harmonious results for each parameter between the Dimension analysers and
between RXL and BN2- Modular DP.
 Disregarding alpha-2 macroglobulin, which cannot be assayed on RXL, the results of FibroTest
and ActiTest were similar to those performed on BN2- Modular DP and RXL.
FT in diagnostic of HBV
Transferability between analyzers
All validated analyzers and reagents are
listed in the technical recommendations
available on www.oneliver.com in the
“For laboratories” section
FT in diagnostic of HBV