In 2006, NKDEP’s Laboratory Working
Group (LWG) conducted a commutability study of creatinine reference
materials with the National Institute of Standards and
Technology’s (NIST) Standard Reference Material (SRM) 967 to
ensure commutability with native serum samples for most commonly used
creatinine methods.
Reference materials are typically used to
establish or validate the calibration traceability of a routine
measurement procedure to a reference measurement procedure of higher
order. When a reference material is intended to be measured by a
routine clinical method, commutability* must be validated for all routine methods for which the reference material is intended for use.
Results
Fresh, frozen serum creatinine reference materials from NIST, SRM 967
(and from the College of American Pathologists’ Accuracy
Calibration Verification/Linearity Survey LN24 used in 2006) were found
to be commutable with a panel of native clinical serum samples for the
manufacturers’ reagents and instruments listed below. Reference
materials and clinical samples were measured by the stated analytical
system and by a LC/IDMS reference measurement procedure at NIST.
Commutability was evaluated using criteria described in Clinical and
Laboratory Standards Institute (CLSI) document EP14-A2.1
Commutable Reagents and Instruments
Manufacturer
|
Reagent (Product Number)
|
Instrument Model
|
Abbott Diagnostics
|
Creatinine (7D64)
|
Abbott AEROSET® System Abbott Diagnostics Creatinine, Next Generation (3L81) Abbott ARCHITECT cSystemsTM c8000
|
Abbott Diagnostics
|
Creatinine (7D64)
|
Abbott ARCHITECT cSystemsTM c8000
|
Abbott Diagnostics
|
Creatinine, Next Generation (3L81)
|
Abbott AEROSET® System
|
Beckman Coulter, Inc.
|
CREA (442760)
|
Synchron® CX4 PRO
|
Beckman Coulter, Inc.
|
CREA (442760)
|
Synchron® Unicel DxC 800
|
Beckman Coulter, Inc.
|
Creatinine (443340)
|
Synchron® CX3 Clinical System
|
Beckman Coulter, Inc.
|
CREm (472525)
|
Synchron® Unicel DxC 800
|
Dade Behring, Inc.
|
Dimension® CREA Flex (DF33A)
|
Dimension® RxL System
|
Olympus Diagnostics Systems
|
Creatinine (OSR6178)
|
Olympus AU400®
|
Olympus Diagnostics Systems
|
Creatinine (OSR6178)
|
Olympus AU640e®
|
Ortho Clinical Diagnostics
|
CREA Slides (814 1947)
|
VITROS® 950 Chemistry System
|
Roche Diagnostic Corporation
|
CREA plus (11775642)
|
Hitachi 911 Analyzer
|
Roche Diagnostic Corporation
|
CREA/RB (12217333)
|
Hitachi 911 Analyzer
|
Siemens Diagnostics
|
Creatinine_2 (B01-4126-01)
|
ADVIA® 1650 Chemistry
|
Siemens Diagnostics
|
Creatinine Enzymatic (B01-4127-01)
|
ADVIA® 1650 Chemistry
|
The list provided above documents
commutability of the NIST SRM 967 and CAP LN24 creatinine reference
materials with native clinical serum samples for various
reagent-instrument combinations determined for specific reagents used
on these specific instrument systems in 2006. It may not apply to
different reagent-instrument combinations.
Because these creatinine reference materials
met the CLSI EP14-A2 criteria for commutability with all
reagent-instrument combinations tested, it is expected that these
reference materials be commutable with native clinical serum samples
when the same reagent is used on very similar instruments using the
same methodological principle.
Nevertheless, caution should be exercised in
extrapolating the above findings to different reagent-instrument
combinations, even when the instruments and reagents are produced by
the same in vitro diagnostic manufacturer. It is recommended that
clinical laboratories consult with the manufacturer(s) of their reagent
and instrument to determine the applicability of the established
commutability characteristics for these reference materials to
particular configurations of creatinine reagents and instrument
systems.
*Definition of Commutability
Commutability has been defined as the equivalence of the mathematical
relationships between the results of different measurement procedures
for a reference material and for representative samples from healthy
and diseased individuals.2 This definition is based on the more technical definition in ISO document 17511.3
Commutability does not imply accuracy or trueness of results, only that
results for a reference material had the same mathematical relationship
between two methods that was observed for native clinical samples
measured by the same two methods.
References
- CLSI Document EP14-A2. Evaluation of Matrix Effects; Approved Guideline. 2nd ed. Wayne, PA: Clinical and Laboratory Standards Institute; 2005.
- Miller WG, Myers GL, Rej R. Why commutability matters. Clinical Chemistry. 2006;52(4):553–554.
- ISO International
Standard 17511:2003(E). In vitro diagnostic medical devices –
Measurement of quantities in biological samples – Metrological
traceability of values assigned to calibrators and control materials.
1st ed. Geneva, Switzerland: International Organization for Standards;
2003.
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