Evaluating estimated glomerular filtration rates of creatinine and cystatin C for male patients with chronic spinal cord injury.

Abstract

Retrospective study OBJECTIVES: To compare the accuracy of estimated serum creatinine (Cre)-based glomerular filtration rates (eGFRcre) and serum cystatin C (CysC)-based eGFR (eGFRcys) for determining renal function in patients with spinal cord injury (SCI). Department of Urology, Tohoku Rosai Hospital, Japan METHODS: Male patients with SCI for longer than 5 years after injury were eligible for inclusion in this study. eGFRcre and eGFRcys were calculated using the following formulas: eGFRcre = 194 × Cre^-1.094 × age^-0.287; eGFRcys = (104 × CysC^-0.1019 × 0.996^age) - 8. The eGFRcre/eGFRcys ratio between 0.8 and 1.2 was considered to be equal, and a relationship between them was investigated. Demographic data, degree of spinal cord damage, management of bladder emptying, post-injury period, and ambulatory status were evaluated. A total of 115 male patients were included. eGFRcre overestimated renal function in 87 (76%) patients with SCI compared with eGFRcys. On univariate analysis, renal function by eGFRcre was overestimated in patients with an eGFRcre of more than 60 ml min^-1 per 1.73 m² (P < 0.001), in non-ambulatory patients (P < 0.001) and, in patients with complete paralysis (P < 0.001). On multivariate analysis, an eGFRcre of more than 60 ml min^-1 per 1.73 m² (P < 0.001), non-ambulatory status (P < 0.001), complete paralysis (P = 0.17), and age (P < 0.001) were independent factors for overestimated renal function by eGFRcre. eGFRcre overestimates renal function compared with eGFRcys. eGFRcys is beneficial, particularly in patients with an eGFRcre of more than 60 ml min^-1 per 1.73 m², in non-ambulatory patients, and in older patients with SCI.