Estimated glomerular filtration rate is a prognosticator of adverse outcomes after primary total knee arthroplasty among patients with chronic kidney disease and glomerular hyperfiltration.

BACKGROUND The goals of this study were: (1) to test whether patients with an Estimated glomerular filtration rate (eGFR) that is higher or lower than population-based standards have an increased risk of 30-day mortality, return to the operating room, readmission, non-home discharge, any complication, major complications, and minor complications after primary total knee arthroplasty (TKA); and (2) to find out whether there is a significant non-linear relationship between eGFR and those same variables. METHODS A total of 168,919 primary TKAs were identified using The National Surgical Quality Improvement Program (NSQIP) database between 1 January 2008 and 31 December 2016. The following outcomes were assessed at 30 days: mortality, return to the operating room, readmission, non-home discharge, any complication, major complications, and minor complications. RESULTS Multivariate binomial logistical regression found that patients with hyperfiltration had higher rates of readmission (P < 0.03), non-home discharge (P < 0.01), any complication (P < 0.01), major complications (P = 0.03), and minor complications (P < 0.01) compared to reference patients with eGFR in the normal range. Patients with an eGFR less than 60 (stage 3 chronic kidney disease or higher) had increased odds of mortality (P < 0.05), readmission (P < 0.05), any complication (P < 0.01), major complications (P < 0.01), and minor complications (P < 0.01). Spline regression found statistically significant non-linear relationships between eGFR and mortality (P < 0.001), return to the operating room (P = 0.0029), and readmission as well as non-home discharge (P < 0.001). CONCLUSION Low eGFR and hyperfiltration may be associated with elevated risk of 30-day adverse events. GFR can be used as a risk stratification tool to counseling patients with particular attention paid to those with a GFR < 30 ml/min/1.73 m2.