Abstract
This study includes clinical laboratories that participated in the first general chemistry proficiency testing survey in 2022 to assess awareness and adoption of new equations from the Chronic Kidney Disease Epidemiology Collaboration for estimated glomerular filtration rate (eGFR) that eliminated race-adjustment factors, including one based on creatinine and one based on creatinine and cystatin C.
In September 2021, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) published new equations for estimated glomerular filtration rate (eGFR) that eliminated race-adjustment factors, including one based on creatinine (2021 CKD-EPI creatinine) and one based on creatinine and cystatin C (2021 CKD-EPI creatinine–cystatin C),1 in an effort to minimize health disparities and reduce inequity in medicine. Numerous professional organizations have endorsed the National Kidney Foundation/American Society of Nephrology Joint Task Force recommendations on incorporation of these equations in clinical practice.2,3,4,5 We assessed awareness and adoption of these equations in US clinical laboratories.
Methods
In March 2022, the College of American Pathologists distributed an optional 5-question survey to clinical laboratories that participated in the first general chemistry proficiency testing survey in 2022 to assess awareness and adoption of the 2021 CKD-EPI equations. Survey respondents were clinical laboratory staff or directors in 50 US states, the District of Columbia, 3 US territories, and 51 other countries. The analysis was limited to laboratories in US states to allow assessment of representativeness. Institution-type differences were analyzed with multivariable logistic regression models with a Bonferroni adjustment. A 2-sided significance level of .05 was used with SAS version 9.4 (SAS Institute Inc). This study was reviewed by the University of Utah institutional review board and did not meet the definition of human participants research.
Results
Of 6317 laboratory proficiency testing participants, 4593 surveys were received. Of these, 295 (6.4%) were excluded due to duplicates from the same site (n = 176), missing key question responses (<3 responses or missing questions 1 and 2; n = 61), or pediatric laboratories for which the 2021 eGFR equations are not applicable (n = 58). The remaining 4298 surveys represent 68.0% of participant laboratories (US, 86.5%; international, 13.5%). Geographic distribution of US state respondents was similar to all US clinical laboratories with certificates of compliance or accreditation from the US Centers for Medicare & Medicaid Services and to US state nonrespondents6 (Table 1).
Table 1. Location of US Clinical Laboratory Respondents Compared With US Laboratories With CMS CLIA Certificates of Compliance or Accreditation and US Nonresponding Laboratories.
| US Census Bureau region and divisiona | No. (%)b | ||
|---|---|---|---|
| US clinical laboratory respondents | US laboratories with CMS CLIA certificates of compliance or accreditationc | US clinical laboratory nonrespondents | |
| Midwest | |||
| East North Central | 559 (15.0) | 3967 (11.7) | 181 (14.0) |
| West North Central | 285 (7.7) | 2816 (8.3) | 65 (5.0) |
| Northeast | |||
| Middle Atlantic | 424 (11.4) | 2672 (7.9) | 133 (10.3) |
| New England | 223 (6.0) | 1275 (3.8) | 70 (5.4) |
| South | |||
| East South Central | 223 (6.0) | 3018 (8.9) | 65 (5.0) |
| South Atlantic | 731 (19.7) | 7715 (22.8) | 284 (21.9) |
| West South Central | 456 (12.3) | 5257 (15.6) | 189 (14.6) |
| West | |||
| Mountain | 291 (7.8) | 2647 (7.8) | 89 (6.9) |
| Pacific | 497 (13.4) | 3433 (10.2) | 198 (15.3) |
| Other | |||
| Other | 29 (0.8)d | 995 (2.9) | 20 (1.5)e |
| Total | 3718 | 33 795 | 1294 |
Abbreviations: CLIA, Clinical Laboratory Improvement Amendments of 1988; CMS, Centers for Medicare & Medicaid Services.
US territories were included in the other category.
Data are from a CMS report6 and are for CMS nonexempt laboratories only because the CMS report for CLIA-exempt states does not differentiate by laboratory type.
The numbers represent the sum of the compliance and accreditation certificate categories. The laboratories classified in the CMS report as international (n = 17) were excluded from the analysis. The CLIA certificate categories of “provider performed microscopy” and “waiver” were not included because these types of testing sites would not be authorized or likely to perform estimated glomerular filtration rate calculations.
Includes 5 laboratories at international US military bases.
Includes 2 laboratories at international US military bases.
Of US respondents, 76.9% reported being aware of the 2021 CKD-EPI equations and 30.3% reported that they already adopted the 2021 CKD-EPI creatinine equation (Table 2). Of the responding laboratories that had not yet adopted the 2021 CKD-EPI creatinine equation, 21.6% planned to adopt the equation before July 1, 2022, 10.7% between July 1 and December 31, 2022, 2.2% in 2023 or later, and 58.4% were unsure regarding future plans.
Table 2. Results of US Laboratory Respondents by Type of Laboratory.
| Question | US laboratories, No. (%) |
Results by type of laboratory, No. (%) | |||
|---|---|---|---|---|---|
| Hospital/medical center (academic) | Hospital/medical center (nonacademic) |
Nonhospital laboratory | Physician office laboratory/clinic | ||
| 1. Is your laboratory aware of the 2021 CKD-EPI equations for eGFR that do not include race adjustment factors?a | |||||
| Yes | 2859 (76.9) | 603 (80.1) | 1503 (76.8) | 554 (76.9) | 199 (68.9) |
| No | 859 (23.1) | 150 (19.9) | 453 (23.2) | 166 (23.1) | 90 (31.1) |
| Total | 3718 | 753 | 1956 | 720 | 289 |
| 2. Has your laboratory adopted the 2021 CKD-EPI creatinine equation for eGFR reporting?b | |||||
| Yes | 1124 (30.3) | 241 (32.1) | 568 (29.1) | 248 (34.6) | 67 (23.2) |
| No | 2059 (55.5) | 415 (55.3) | 1116 (57.2) | 356 (49.7) | 172 (59.5) |
| Unsure | 525 (14.2) | 95 (12.6) | 268 (13.7) | 112 (15.6) | 50 (17.3) |
| Total | 3708 | 751 | 1952 | 716 | 289 |
| 3. When does your laboratory plan to adopt the 2021 CKD-EPI creatinine equation for eGFR reporting?c | |||||
| Before July 1, 2022 | 440 (21.6) | 96 (23.6) | 256 (23.2) | 53 (15.0) | 35 (20.7) |
| Between July 1 and December 31, 2022 | 218 (10.7) | 47 (11.5) | 125 (11.3) | 36 (10.2) | 10 (5.9) |
| 2023 or later | 45 (2.2) | 10 (2.5) | 23 (2.1) | 9 (2.5) | 3 (1.8) |
| Unsure | 1187 (58.4) | 227 (55.8) | 644 (58.3) | 219 (62.0) | 97 (57.4) |
| Not applicable; do not plan to implement this equation | 144 (7.1) | 27 (6.6) | 57 (5.2) | 36 (10.2) | 24 (14.2) |
| Total | 2034 | 407 | 1105 | 353 | 169 |
| 4. Does your laboratory plan to adopt the 2021 CKD-EPI creatinine–cystatin C equation for eGFR reporting?d | |||||
| Yes | 292 (8.0) | 67 (8.9) | 149 (7.7) | 56 (7.9) | 20 (7.0) |
| No | 1174 (32.0) | 237 (31.6) | 590 (30.5) | 240 (34.0) | 107 (37.5) |
| Unsure | 2082 (56.7) | 418 (55.8) | 1128 (58.4) | 383 (54.3) | 153 (53.7) |
| Not applicable; we have already implemented this equation | 123 (3.4) | 27 (3.6) | 65 (3.4) | 26 (3.7) | 5 (1.8) |
| Total | 3671 | 749 | 1932 | 705 | 285 |
| 5. Are there any barriers impacting your laboratory’s consideration or adoption of the 2021 CKD-EPI creatinine–cystatin C equation for eGFR reporting? (multiple responses allowed) | |||||
| Limited cystatin C testing options | 1310 (58.5) | 274 (58.5) | 716 (59.6) | 231 (58.2) | 89 (51.7) |
| Cost of testing | 523 (23.4) | 105 (22.4) | 282 (23.5) | 95 (23.9) | 41 (23.8) |
| Staffing resourcese | 519 (23.2) | 119 (25.4) | 297 (24.7) | 67 (16.9) | 36 (20.9) |
| Patient populationf | 257 (11.5) | 48 (10.3) | 124 (10.3) | 53 (13.4) | 32 (18.6) |
| Other | 448 (20.0) | 91 (19.4) | 234 (19.5) | 90 (22.7) | 33 (19.2) |
| Total respondents | 2239 | 468 | 1202 | 397 | 172 |
Abbreviations: CKD-EPI, Chronic Kidney Disease Epidemiology Collaboration; eGFR, estimated glomerular filtration rate.
P < .001 for comparison of hospital/medical center (academic) vs physician office laboratory/clinic. P = .02 for comparison of hospital/medical center (nonacademic) vs physician office laboratory/clinic. Other comparisons were not significant.
P = .008 for comparison of hospital/medical center (nonacademic) vs nonhospital laboratory. P = .003 for comparison of nonhospital laboratory vs physician office laboratory/clinic. Other comparisons were not significant.
P = .005 for comparison of hospital/medical center (academic) vs physician office laboratory/clinic. P < .001 for comparison of hospital/medical center (nonacademic) vs physician office laboratory/clinic. Other comparisons were not significant.
None of the comparisons was statistically significant.
P = .01 for comparison of hospital/medical center (academic) vs nonhospital laboratory. P = .008 for comparison of hospital/medical center (nonacademic) vs nonhospital laboratory. Other comparisons were not significant.
P = .03 for comparison of hospital/medical center (academic) vs physician office laboratory/clinic. P = .01 for comparison of hospital/medical center (nonacademic) vs physician office laboratory/clinic. Other comparisons were not significant.
Of US respondents, 3.4% reported that they already adopted the 2021 CKD-EPI creatinine–cystatin C equation, 8.0% reported that they planned to adopt it, 32.0% reported that they did not plan to adopt it, and 56.7% were unsure (Table 2). The 3 most common barriers to adoption of the 2021 CKD-EPI creatinine–cystatin C equation were limited cystatin C testing options, cost of testing, and staffing resources.
Reported awareness of the 2021 CKD-EPI equations was higher in US hospital laboratories (academic, 80.1%, P < .001; nonacademic, 76.8%, P = .02) vs physician office laboratories (68.9%) (Table 2). Nonhospital laboratory (eg, referral) respondents reported similar awareness as hospital laboratories. Adoption of the new equations by different types of laboratories also appears in Table 2.
Discussion
The survey results demonstrated that most participating US state clinical laboratories reported being aware of the 2021 CKD-EPI equations and a large proportion had adopted or were planning to adopt the 2021 CKD-EPI creatinine equation as of March 2022. The 2021 CKD-EPI creatinine equation will enable standardized eGFR values for clinical practice decisions in patients with kidney disease. Guidance is now available to assist clinical laboratories with implementation.3
Few laboratories reported that they have moved forward with implementation of the 2021 CKD-EPI creatinine–cystatin C equation. Referral laboratories are an option for cystatin C testing when it is not performed in-house.
Limitations of this study include distribution of the survey only to laboratories that participated in this proficiency testing event, limited publicly available data on representativeness, the short interval between publication of the 2021 CKD-EPI equations and the survey, and the absence of questions regarding availability of cystatin C or why an “unsure” response was given.
Section Editors: Jody W. Zylke, MD, Deputy Editor; Kristin Walter, MD, Senior Editor.
References
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