Prospective Study of Methods of Renal Function Evaluation in Patients With Neurogenic Bladder Dysfunction

ObjectiveTo evaluate the precision of methods used to assess renal function in patients with neurogenic voiding dysfunction.Materials and MethodsThis multicenter prospective study, which was set in Toulouse and Lyon, France, included 60 patients (mean age, 48.9 ± 15.2 years) with neurogenic bladder and sphincter dysfunction. The correlation and the concordance with the inulin clearance of each method of renal function evaluation were assessed.ResultsThe correlation of serum creatinine with inulin clearance was low when using serum creatinine-based equations such as the Modification of Diet in Renal Disease (simplified and complete) and Cockcroft-Gault equations. The r and r2 coefficients were higher for creatinine-based methods, such as 24-hour (r = 0.72) and 3-hour creatinine clearance (r = 0.78). The strongest correlation was found for serum cystatin C–based equations: the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine/cystatin C combined equation (r = 0.78) and the CKD-EPI cystatin C equation (r = 0.80). Mean bias of serum creatinine–based equations estimating glomerular filtration rate, the Cockcroft-Gault, and the simplified and complete Modification of Diet in Renal Disease equations, was 27.5 ± 28.6, 17.48 ± 29.40, and 21.98 ± 30.40 mL/min, respectively. Mean bias of creatinine clearance was 19.89 ± 15.30 mL/min at 3 hours and 19.00 ± 31.08 mL/min at 24 hours. Mean bias of the CKD-EPI cystatin C and the CKD-EPI creatinine/cystatin C combined equations was 11.98 ± 17.68 mL/min and 18.62 ± 17.85 mL/min, respectively. Limitations are the numerous types of neurologic diseases.ConclusionThe CKD-EPI equation using cystatin C was the most precise method of renal function evaluation in patients with neurogenic bladder.