Prospective study of methods of renal function evaluation in patients with neurogenic bladder dysfunction.

OBJECTIVE: To evaluate the precision of methods used to assess renal function in patients with neurogenic voiding dysfunction.

MATERIALS AND METHODS: This 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.

RESULTS: The 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 r(2) 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.

CONCLUSION: The CKD-EPI equation using cystatin C was the most precise method of renal function evaluation in patients with neurogenic bladder.