Influences on renal function in chronic spinal cord injured patients

The optimal method of bladder management in the spinal cord injured population remains controversial. We determined the significance of bladder management and other factors on renal function in this population.

We retrospectively reviewed the medical records and upper tract imaging studies of 308 patients with a mean followup of 18.7 years since injury. Renal function was assessed by serum creatinine, creatinine clearance and proteinuria measurement, and by upper tract abnormalities on renal ultrasound and nuclear medicine renal scan. Independent variables evaluated for an influence on renal function included patient age, interval since injury, injury level and completeness, vesicoureteral reflux, history of diabetes mellitus and bladder management method.

Mean serum creatinine plus or minus standard deviation in patients on chronic Foley catheterization, clean intermittent catheterization and spontaneous voiding was 1.08 +/- 0.99, 0.84 +/- 0.23 and 0.97 +/- 0.45 mg./dl. (analysis of variance p = 0.05, Student's t test p = 0.10), and mean creatinine clearance was 91.1 +/- 46.5, 113.4 +/- 39.8 and 115 +/- 49 ml. per minute, respectively (analysis of variance and Student's t test p <0.01), respectively. Proteinuria was present in 19 patients (6.2%) in the Foley catheterization, 3 (1%) in the clean intermittent catheterization and 4 (1.3%) in the spontaneous voiding group (chi-square test p <0.01), while there were upper tract abnormalities in 56 (18.2%), 20 (6.5%) and 24 (7.8%) patients, respectively (chi-square test p <0.01). Multiple regression analyses revealed no significant predictors of serum creatinine, although older patient age and Foley catheterization significantly predicted low creatinine clearance. Additional logistic regression analyses showed that Foley catheterization was associated with proteinuria and vesicoureteral reflux was associated with upper tract abnormalities.

While renal function may be preserved by all forms of bladder management, chronic indwelling catheters may contribute to renal deterioration.