Urolastic®, a new bulking agent for treatment of stress urinary incontinence: a systematic review and meta-analysis

A Clinical Learning Curve Study of Polydimethylsiloxane Urolastic for Stress Urinary Incontinence: Does Safety Improve when Expertise Grow?

OBJECTIVES

The aim of the study was to characterize the learning curve of bulk injection therapy polydimethylsiloxane Urolastic (PDMS-U) for stress urinary incontinence.

DESIGN

Secondary analysis from three clinical studies on efficacy and safety outcomes of PDMS-U was performed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

PDMS-U-certified physicians who performed ≥4 procedures were included. The primary outcome was the number of PDMS-U procedures needed to achieve acceptable failure rates for "complications overall," "urinary retention," and "excision," using the LC-CUSUM method. For the primary outcome, physicians who performed ≥20 procedures were used. For the secondary outcome, logistic and linear regression analysis was used to assess the relationship between number of procedures, complications (complications overall, urinary retention, pain, exposure, excision of PDSM-U), and duration of treatment.

RESULTS

In total, 203 PDMS-U procedures were performed by nine physicians. Five physicians were used for the primary outcome. For "complications overall," "urinary retention," and "excision," two physicians reached a level of competence: one at procedure 20 and one at procedure 40. The secondary outcome showed no statistically significant association between procedure number and complications. There was a statistically significant increase in the duration of treatment with more physician experience (mean difference 0.83 min per 10 additional procedures, 95% CI: 0.16-1.48).

LIMITATIONS

One limitation is that retrospectively collected data might have underreported the number of complications. Secondly, there was variation in the way the technique was applied between physicians.

CONCLUSIONS

Physicians' experience in the PDMS-U procedure did not influence safety outcomes. There was large inter-physician variability and most physicians did not reach acceptable failure rates. There was no relationship between PDMS-U complications and the number of performed procedures.

Particulate Versus Non-Particulate Bulking Agents In The Treatment Of Stress Urinary Incontinence

Stress urinary incontinence (SUI) has been treated surgically with the midurethral sling but in recent years, this option has come under scrutiny and the risk-benefit balance continues to be reviewed. The low-risk alternative for women with uncomplicated SUI is the bulking agent, which aims to achieve continence through coaptation of the urethra. Two classes of bulking agents can be identified: those made from solid microparticles in an absorbable liquid or gel carrier (particulate agents) and those comprising a homogenous gel (non-particulates) that resists absorption. Polydimethylsiloxane®, carbon-coated zirconium oxide®, calcium hydroxyapatite® and polyacrylate polyalcohol copolymer® are currently marketed particulate agents. With the exception of calcium hydroxyapatite, the particles are non-degradable. Each agent achieves its long-term bulking effect through reactive changes around the persisting particles while the carrier volume is lost. Bulkamid® is a non-particulate agent with the bulking effect resulting from the volume of gel injected. The lasting network of fine fibers formed by the host tissue anchors the gel in situ. Foreign-body granulomas, erosion and migration/material extrusion and loss of bulk have been observed in connection with the particle-based products. Bulkamid may be mechanistically less liable to these events; however, there are minimal data directly comparing the two types of bulking agent. The question of durability is inevitable based on their differing modes of action.