Of the surveyed CAP-accredited laboratories that were reporting eGFR, 86% were reporting eGFR with every creatinine measured in 2017, 2013, and 2012. A slight increase from frequencies in 2007-2011, but a significant increase from only 23% in 2003.
Chart Explanation: 86% of the laboratories reporting eGFR were reporting with every creatinine measured in 2017. This represents a nearly 4-fold increase from 2003, when only 23% of laboratories were reporting eGFR with every creatinine tested. Most of the remaining laboratories reported eGFR on an as-requested basis (9%; > 4-fold decrease from 2003, when 41% reported on an as-requested basis). The remaining laboratories reported eGFR using different rules, such as outpatient orders only.
The College of American Pathologists (CAP) performs regular surveys of CAP-accredited laboratories. The General Chemistry C-B Survey of laboratories that performed routine chemistries (representing an estimated 80% or more of U.S. laboratories performing routine chemistries) included a supplemental survey of eGFR reporting; creatinine calibration practices were queried in a separate survey that was purchased by laboratories and thus may not be representative of all laboratories performing creatinine assays.
In June of 2003, 2005, and 2007, annually from 2008 to 2013, and then 2017, CAP included in its General Chemistry C-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 sent a questionnaire regarding their eGFR reporting practices (2013 n=5,183 responding laboratories).
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 do 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/IDMS-traceable 4-parameter MDRD Study equation (added 2011)/6-parameter MDRD Study equation/CKD-EPI equation (added 2011)/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 have been 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; http://nkdep.nih.gov/labprofessionals/Clinical_Laboratories.htm).
|Analytic Considerations||Denominator should be defined if possible. Method, standards & frequency can only be obtained within those reporting eGFR/IDMS-traceable calibration|
|Description of Measure||Laboratory reporting of eGFR|
|Data Source||College of American Pathologists|
|Type of Data Source||Private|
|Data Set||General Chemistry C-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|
|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, annually from 2008-2013, and then 2017 (cross-sectional) for chemistry survey|
|U.S. Region Covered by Primary Variable||All; some international laboratories (unknown %) included|
|Period Currently Available||2017|
|Additional Data Items of Interest||Method of estimation, reporting standards, frequency of reporting|
|Limitations of Indicator||Only those laboratories who chose to participate (who performed general chemistry including creatinine) and responded to the survey were included (response rate 60-77%, depending on survey year); 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); number of laboratories do not represent volume of patients; IDMS-traceable MDRD and CKD-EPI equations only added in later surveys|