Performance of creatinine- and cystatin C-based formulas to estimate glomerular filtration rate

A retrospective multi-site examination of chronic kidney disease using longitudinal laboratory results and metadata to identify clinical and financial risk

BACKGROUND

A retrospective observational study was conducted at 3 health care organizations to identify clinical gaps in care for patients with stage 3 or 4 chronic kidney disease (CKD), and financial opportunity from U.S. risk adjustment payment systems. Lack of evaluation for CKD in patients with diabetes was also assessed.

METHODS

Outpatient longitudinal laboratory results and patient metadata available in the electronic medical record, laboratory information system, and/or laboratory billing or facility claims data for the calendar year 2021 were evaluated. Laboratory results were compared to billing data (ICD-10 codes) and risk adjustment scores including Hierarchical Condition Categories (HCC) to determine if laboratory-identified CKD was coded as a disease condition in the electronic medical record. Adults 18 to 75 years of age were included; inpatient laboratory results and pregnant individuals were excluded.

RESULTS

At the 3 institutions, 12,478 of 16,063 (78%), 487 of 1511 (32%) and 19,433 of 29,277 (66%) of patients with laboratory evidence of stage 3 or 4 CKD did not have a corresponding ICD-10 or HCC code for CKD in the electronic medical record. For patients at the 3 institutions with diabetes on the basis of an HbA1c value of ≥ 6.5%, 34,384 of 58,278 (59%), 2274 of 2740 (83%) and 40,378 of 52,440 (77%) had not undergone guideline-recommended laboratory testing for CKD during the same 12 months. Using publicly available data for calendar year 2021, an estimated 3246 of 32,398 patients (9.9%) at the 3 institutions with undocumented CKD stages 3-4 would be enrolled in Medicare Advantage or Affordable Care Act Marketplace programs. The imputed lost reimbursement under risk-adjusted payment systems for under-documentation of CKD in this subset of patients was $2.85 M for the three institutions combined, representing lost opportunity for both identification and proactive clinical management of these patients, and financial recovery for the costs of providing that care.

CONCLUSIONS

Clinical laboratories can provide value beyond routine diagnostics, helping to close gaps in care for identification and management of CKD, stratifying subgroups of patients to identify risk, and capturing missed reimbursement through risk adjustment factors.

Comparison of estimated glomerular filtration rate equations based on serum creatinine-, cystatin C- and creatinine-cystatin C in elderly Chinese patients

BACKGROUND

This study aimed to further evaluate the accuracy of eleven GFR equations in different subgroups of an elderly Chinese hospitalized population.

METHODS

All participants of the study were divided into seven separate groups including age-subgroup, sex-subgroup, GFR Staging-subgroup and whether combined with diabetic, hypertensive, coronary heart disease (CHD) and cerebrovascular disease. Referring to Tc-99m-DTPA dual plasma sample clearance method, six serum creatinine (Cr)-based [Cockcroft-Gault (CG), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI_Cr), Lund-Malmö Revised (LMR), Berlin Initiative Study (BIS1), Full Age Spectrum (FAS_Cr) and European Kidney Function Consortium (EKFC)], two serum cystatin C(Cys)-based (CKD-EPI_Cys and FAS_Cys), and three Cr-Cys combination based (CKD-EPI_Cr-Cys, BIS2 and FAS_Cr-Cys) equations were employed. Bias, interquartile range of the median difference (IQR), P30, and GFR misclassification rate were calculated to compare the performance of the selected equations.

RESULTS

A total of 359 elderly Chinese patients were enrolled. Overall, median mGFR was 36.91(25.26,56.32)ml/min/1.73 m². Smaller biases (ml/min/1.73 m²) were shown in CKD-EPI_Cr and BIS1 equations (0.75 and 0.61). IQR (ml/min/1.73m²) was least with BIS2 equation and FAS_Cr-Cys equation (10.34 and 10.65). For accuracy (P30), performance of FAS_Cr-Cys, BIS2, and BIS1 equation was superior (78.3%, 78.0%, and 74.7%, respectively). In terms of RMSE (ml/min/1.73 m²), BIS1 and FAS_Cr-Cys equation performed better (12.44 and 12.51).

CONCLUSIONS

Overall, this study showed that the eGFR equations were less accurate in the diabetic and non-hypertension group than in the non-diabetic and hypertension group, respectively. Among all enrolled equations, the BIS2 and FAS_Cr-Cys equations might be the best choice to evaluate glomerular filtration rate in Chinese elderly patients.