Comment: The quality of evidence is downgraded by study quality (inadequate or unclear allocation concealment) and by imprecise results (few patients and wide confidence intervals).
Periurethral injection of bulking agents is suggested for women with stress urinary incontinence and a considerable operative risk.
The recommendation is weak because of weaker effectiveness compared with surgery.
A Cochrane review (abstract [Abstract], review [Abstract]) included 14 studies with a total of 2004 subjects. The limited data available were not suitable for meta-analysis. Injection therapy showed early benefit compared with conservative treatment with respect to continence grade (RR 0.7, 95% CI 0.52 to 0.94; 1 trial, n=45) and quality of life (RR 0.54, 95% CI 0.16 to 0.92). Injection of autologous fat was compared to placebo in a study of 68 women which was terminated early because of safety concerns. No differences in subjective or objective outcome were found in the two groups. Two studies that compared injection with surgical management found significantly better objective outcome in the surgical group (RR 4.77, 95% CI 1.96 to 11.64). Eight studies compared different agents - all results had wide confidence intervals. Silicone particles, calcium hydroxylapatite, ethylene vinyl alcohol and carbon spheres gave improvements equivalent to collagen. Porcine dermal implant gave improvements comparable to silicone at six months. A comparison of periurethral and transurethral methods of delivery of the bulking agent found similar outcome but a higher rate of early complications in the periurethral group.
A meta-analysis 2 included 6 trials with a total of 710 patients. Bulking agents were less effective than surgical procedures according to subjective improvement after treatment (RR = 0.70, 95% CI 0.53 to 0.92, p = 0.01). There was no statistically significant difference between these two methods with regard to complications after the intervention.
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