Comparison of glomerular filtration rate estimating equations in older adults: A systematic review and meta-analysis

Debates persist regarding the performance of existing glomerular filtration rate (GFR) estimating equations in older individuals. We performed this meta-analysis to assess the accuracy and bias of six commonly used equations, including the Chronic Kidney Disease Epidemiology Collaboration creatinine equation (CKD-EPI_Cr) and its combination with cystatin C (CKD-EPI_Cr-Cys), with the corresponding pair of the Berlin Initiative Study equations (BIS1 and BIS2) and the Full Age Spectrum equations (FAS_Cr and FAS_Cr-Cys).

PubMed and the Cochrane Library were searched for studies comparing estimated GFR (eGFR) with measured GFR (mGFR). We analyzed the difference in P30 and bias among the six equations and investigated subgroups based on the area (Asian and non-Asian), mean age (60-74 years and ≥75 years), and levels of mean mGFR (<45 mL/min/1.73m² and ≥45 mL/min/1.73m²).

27 studies with 18,112 participants were included, all reporting P30 and bias. BIS1 and FAS_Cr exhibited significantly higher P30 than CKD-EPI_Cr. While no significant differences were observed between FAS_Cr and BIS1, or among the three combined equations in terms of either P30 or bias. Subgroup analyses revealed FAS_Cr and FAS_Cr-Cys achieved better results in most situations. However, in the subgroup of mGFR<45 mL/min/1.73m², CKD-EPI_Cr-Cys had relatively higher P30 and significantly smaller bias.

Overall, BIS and FAS provided relatively more accurate estimates of GFR than CKD-EPI in older adults. FAS_Cr and FAS_Cr-Cys may be better suited for various conditions, while CKD-EPI_Cr-Cys would be a better option for older individuals with impaired renal function.