A meta-analysis of botulinum toxin sphincteric injections in the treatment of incomplete voiding after spinal cord injury

Objective: To conduct a systematic review and meta-analysis to examine the effect of injecting botulinum toxin A (BTX-A) into the detrusor sphincter on improving bladder emptying in individuals with spinal cord injury (SCI).

Data sources: MEDLINE, CINAHL, EMBASE, and PsycINFO databases were searched for all relevant articles published from 1980 to September 2011.

Data selection: All trials examining the use of BTX-A injections into the detrusor sphincter for the treatment for incomplete bladder emptying after SCI were included if at least 50% of the study sample comprised subjects with SCI, and if the SCI sample size was 3 or greater.

Data extraction: A standardized mean difference (SMD) ± SE and 95% confidence interval (CI) were calculated for each outcome of interest, and the results were pooled using a fixed or random effects model, as appropriate. Outcomes assessed included postvoid residual urine volume (PRV), detrusor pressure (PDet), and urethral pressure (UP). Effect sizes were interpreted as small, 0.2; moderate, 0.5; and large, 0.8.

Data synthesis: A relatively limited number of studies (2 randomized controlled trials, 6 uncontrolled trials) were identified. The 8 studies included results from 129 subjects. There was a statistically significant decrease in PRV at 1 month (SMD=1.119±.140; 95% CI, .844-1.394; P<.001), with a pooled mean PRV decrease from 251.8 to 153.0 mL. There was a moderate statistical effect on PDet (SMD=.570±.217; 95% CI, .145-.995; P=.009); pooled PDet decreased from 88.7 to 20.5 cmH(2)O. A large statistical effect size on UP (SMD=.896±.291; 95% CI, .327-1.466; P=.002) and an improvement from 119.7 to 102.3 cmH(2)O were seen. The systematic review also indicated a 50% reduction in urinary tract infections based on 3 studies. Discontinuation or reduction in catheter usage was reported in 4 studies after BTX-A.

Conclusions: Results of the meta-analysis indicate that BTX-A is effective in reducing PRV and demonstrating a statistically significant reduction in PDet and UP 1 month postinjection. However, the clinical utility of BTX-A is yet to be determined.