About one-half (48%) surveyed by the College of American Pathologists(CAP) reported using IDMS-traceable calibration with serum creatinine at the end of 2008.
All major global manufacturers are only distributing IDMS-traceable serum creatinine methods in all markets they serve as the end of 2009.
Nearly half of responding laboratories reporting using IDMS-traceable calibration in the last third of 2008; the proportion has more than tripled since 2006 (15%). Although there has been a steady rise since 2006 in the implementation of IDMS-traceable creatinine by laboratories, more than half of the laboratories responding to this survey still had not made the transition as of the end of 2008. Data prior to 2008 may be inaccurate because many laboratories were not aware that the manufacturer may have performed the recalibration. Because there are two 4-parameter MDRD Study equations, one for historical or traditional calibration (Levey et al., 1999) and one for IDMS-traceable calibration (Levey et al., 2006), it is important that laboratories be aware of the type of calibration being used. Because manufacturers have globally switched to the IDMS-traceable creatinine assay, this variable will likely not be tracked going forward.
In June of 2003, 2005, 2007, 2008, 2009, and 2010, the College of American Pathologists (CAP) performed its General Chemistry B Survey, in which all CAP-accredited laboratories that performed routine chemistries (representing an estimated 80% or more of U.S. laboratories performing routine chemistries) were queried regarding their eGFR reporting practices (response rates, 60%, 76%, and 77% in 2007, 2008, and 2009, respectively). In a supplemental survey, laboratories were asked “Does your institution report an estimated Glomerular Filtration Rate (GFR) based on a serum or plasma creatinine measurement without measuring urine creatinine?” (yes/no); “If yes, when to you report the estimated GFR?” (with all measured serum or plasma creatinine determinations/only when specifically requested/other); and “If your institution reports an estimated GFR, what formula is used?” (4-parameter MDRD Study equation/6-parameter MDRD Study equation/Cockcroft-Gault/not sure/other). In the creatinine accuracy calibration survey, which is purchased by laboratories for self-assessment, CAP asked participants to state their creatinine calibration method: IDMS-traceable versus traditional calibration. Note that manufacturers were polled in June 2009; it was found that all major global manufacturers are currently only distributing IDMS-traceable serum creatinine methods (as of the end of 2009) in all markets they serve. All existing lots of older calibration reagents should be used up during 2010 (exceptions: the Siemens Dimension/Vista Jaffe method which will continue with its current calibration traceability and the Nova Biomedical blood gas instrument creatinine measurement). Some smaller manufacturers were not represented in the inquiry but all major North American and global manufacturers responded (Miller, 2009).
|Description of Measure||Laboratory reporting of eGFR and creatinine calibration|
|Data Source||College of American Pathologists|
|Type of Data Source||Private|
|Data Set||General Chemistry B Survey results|
|Health Care System Data||No|
|Regional or National?||National|
|Demographic Group||CAP-accredited laboratories performing general chemistry who responded to surveys|
|Numerator||CAP-accredited laboratories who reported eGFR/IDMS-traceable creatinine calibration|
|Denominator||CAP-accredited laboratories who responded to survey|
|Glomerular filtration rate||Method of estimation of GFR varied by laboratory and was part of survey|
|Primary Data Source Indicator||Number of U.S. CAP-accredited laboratories who performed general chemistry and reported eGFR/IDMS-traceable calibration|
|Primary Indicator Method of Measurement||Survey|
|Frequency of Measurement (Primary)||Bi-annual to 2007, then annual (cross-sectional) for chemistry survey; three times per year for creatinine survey|
|U.S. Region Covered by Primary Variable||All; some international laboratories (unknown %) included|
|Period Currently Available||2006C–2008C|
|Pending Data||2011 (no pending data for creatinine calibration)|
|Additional Data Items of Interest||Method of estimation, reporting standards, frequency of reporting|
|Limitations of Indicator||Only those laboratories who were chosen to participate (who performed general chemistry including creatinine) and responded to the survey were included (response rate 60-77%, depending on survey); recall bias; international labs included; for creatinine calibration, lab may be unfamiliar with manufacturer’s calibration practice; unknown representativeness of CAP laboratories (although estimated at >80% of U.S. labs)|
|Analytical Considerations||Denominator should be defined if possible. Method, standards & frequency can only be obtained within those reporting eGFR/IDMS-traceable calibration|
References and Sources:
Miller WG. Reporting estimated GFR: a laboratory perspective. Am. J. Kidney Dis. 2008;52(4):645-648.
Levey AS, Bosch JP, Lewis JB, Greene T, Rogers N, Roth D. A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equation. Modification of Diet in Renal Disease Study Group. Ann Intern Med. 1999;130(6):461-70.
Levey AS, Coresh J, Greene T, et al. Chronic Kidney Disease Epidemiology Collaboration. Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate. Ann Intern Med. 2006;145(4):247-54.