Clinical Significance of Urodynamic Study Parameters in Maintenance of Renal Function in Spinal Cord Injury Patients

OBJECTIVE: To analyze association between urodynamic study (UDS) parameters and renal function in spinal cord injured (SCI) patients with neurogenic detrusor overactivity. METHODS: Patients with a suprasacral SCI, who underwent UDS and radioisotope renogram at least twice between January 1, 2006 and January 31, 2013, were included. UDS (cystometric capacity, reflex volume, compliance, and maximal detrusor pressure) and radioisotope renogram (total effective renal plasma flow [ERPF] of both kidneys) data were collected. The following were conducted to reanalyze any association between reflex volume and ERPF: initial and follow-up results of consecutive evaluations were compared; a mixed-model regression analysis to account for clustered data was conducted to evaluate the association between UDS parameters and ERPF; and finally, a mixed-model analysis type 3 test with data pairs, of which the first evaluation showed involuntary detrusor contraction. RESULTS: A total of 150 patients underwent 390 evaluations which were arranged into 240 pairs of consecutive evaluations, of which 171 had first evaluations with observed involuntary detrusor contraction. The following results were obtained: cystometric capacity was significantly larger and maximal detrusor pressure was significantly lower on follow-up; on univariate analysis, reflex volume and maximal detrusor pressure were significant, and multivariate analysis using these two parameters showed that maximal detrusor pressure is significantly associated with total ERPF; and no significant differences were observed. CONCLUSION: Maximal detrusor pressure should be closely monitored in the urologic management of neurogenic detrusor overactivity in SCI patients. The results also may serve as a reference for regular UDS follow-up.