In 2019, 76% of laboratories surveyed by the College of American Pathologists (CAP) were using an IDMS-traceable calibration with serum creatinine, a slight decrease from 2017 (78%), but a significant increase from 2007 (26%).
More than three-quarters (76%) of responding laboratories reported using IDMS-traceable calibration in 2019; the proportion has more than quadrupled since 2006 (15%). There has been a steady rise since 2006 in the implementation of IDMS-traceable creatinine by laboratories. 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), laboratories should 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 2006, 2007, 2008, 2011-2013, and then 2017 and 2019, the College of American Pathologists (CAP) performed its General Chemistry 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).
General Chemistry Survey results
Bi-annual to 2007, annually from 2008-2013, and then 2017 and 2019 (cross-sectional) for chemistry survey; three times per year for creatinine survey