{"doi":"10.1093/clinchem/hvac195","title":"Concordance of Chronic Kidney Disease Stage and Metformin Management Using CKD-EPI 2021 Race-Free Equation vs CKD-EPI 2009 Equation to Estimate Glomerular Filtration Rate","abstract":"To the Editor: Metformin is a first-line agent for the treatment of hyperglycemia in type 2 diabetes. However, the risk of lactic acidosis necessitates close monitoring of renal function (1). The Kidney Disease: Improving Global Outcomes (KDIGO) organization clinical practice guidelines recommend using an estimation of glomerular filtration rate (eGFR) to assess renal function, categorize chronic kidney disease (CKD) stage, and guide metformin management (2). Multiple professional organizations have recommended implementation of the new CKD Epidemiology Collaboration (CKD-EPI) 2021 race-free eGFR equation, calculated from creatinine (eGFRcr), that does not disproportionately affect any one group of individuals (35). In order to assess the potential impact of implementation, a retrospective analysis was performed to determine concordance of CKD stage and metformin management categories using the CKD-EPI 2021 vs CKD-EPI 2009 eGFRcr equations. Creatinine concentration (first result used if multiple measurements available), age, hemoglobin A1c (HbA1c), and race from patients 18 years old with an active metformin medication between April 1, 2021, and July 1, 2021, were retrieved from the electronic health record. eGFRcr was calculated from reported serum creatinine (mg/dL) using both the CKD-EPI 2021 and CKD-EPI 2009 equations. Concordance, defined as the number (percentage) of eGFRcr values that fell into the same CKD stage and metformin management categories using each equation, was evaluated in both self-reported Black and non-Black patients. Patients whose race was listed as unknown in the medical record were excluded. Metformin management recommendation categories were defined according to the KDIGO Clinical Practice Guidelines for the Evaluation and Management of Chronic Kidney Disease. KDIGO recommends continuing metformin use in patients with an eGFRcr 45 mL/min/1.73 m2 (CKD-1 to -3a), reviewing use for potential dosage adjustments with an eGFRcr 30 to 44 (CKD-3b), and discontinuing use when eGFRcr is 30 (CKD-4 to -5). A total of 6757 unique individuals were identified with an active metformin prescription and creatinine measurement during the 3-month interval (IRB-22-0205). Patient demographics in the sample cohort were self-reported Black (n 2076; 30.7) or non-Black (n 4681; 69.3) individuals. The cohort was 53.6 female and 46.4 male ranging in age from 18 to 99 years old (mean 61.9 13.5 years). The mean and SD of serum creatinine for all individuals was 0.95 (84 umol/L) and 0.48 mg/dL (42 umol/L) with a range of 0.20 (17 umol/L) to 15.52 mg/dL (1372 umol/L). Concordance of CKD stage was 79.6 (n 1652/2076) and 86.4 (n 4043/4681) for self-reported Black and non-Black individuals, respectively, with an overall concordance of 84.3 (n 5695/6757) using the CKD-EPI 2021 eGFRcr vs CKD-EPI 2009 eGFRcr equations (Table 1). The remaining 15.7 (n 1062/6757) of patients were reclassified to a different CKD stage using the CKD-EPI 2021 equation. As anticipated, eGFRcr was lower for self-reported Black individuals while higher for non-Black individuals using the CKD-EPI 2021 race-free eGFRcr equation. Concordance of CKD stage for patients with active metformin prescriptions. Bold numbers indicate a change in KIDGO metformin management category with the 2021 CKD-EPI eGFRcr equation. Concordance of CKD stage for patients with active metformin prescriptions. Bold numbers indicate a change in KIDGO metformin management category with the 2021 CKD-EPI eGFRcr equation. KIDGO metformin management category changed for 69 (3.3) Black individuals with an active metformin prescription (bold text, Table 1). For Black individuals previously in CKD-3a (Recommendation: continue metformin use), 27.8 (n 55/198) were reclassified to CKD-3b (Recommendation: review metformin use) and 13.0 (n 14/108) previously in CKD-3b were reclassified to CKD-4 (Recommendation: discontinue metformin use). Metformin management category changed for 90 (1.9) non-Black indiv","journal":"Clinical Chemistry","year":2022,"id":279758,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":4,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9577,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2022-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":953327,"name":"Nichole Korpi‐Steiner","orcid":"0009-0007-7924-599X","position":1,"is_corresponding":false},{"id":597519,"name":"Steven W. Cotten","orcid":"0000-0003-1431-9883","position":2,"is_corresponding":false},{"id":488560,"name":"Robert Maynard","orcid":"0000-0002-7590-2442","position":0,"is_corresponding":true}],"reference_count":6,"raw_metadata":null,"created_at":"2026-07-19T00:28:55.546964Z","pmid":"36508321","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}