Debate: Injectables as a first-line treatment for SUI
By Kristin Jenkins

QUEBEC CITY, Que. – Is a periurethral injectable such as collagen the right choice as a first-line treatment for stress urinary incontinence (SUI)? The answer, according to presenters here at Urogynecology Quebec 2007 appears to be “yes” and “sometimes, no.”

Although he was invited to present an argument against the use of injectables, Dr. J. Christian Winters prefaced his comments by saying, “I inject a whole lot of women, many of whom have never had treatment for stress incontinence before.” Dr. Winters is professor and chairman, Louisiana State University Health Sciences Center, New Orleans, LA.

Dr. Winters added that: “There is no compelling data at present to suggest we are doing better than collagen as a first-line treatment for SUI.” Injectables are also easy on the patient, he noted, “…since the procedure can be done on an outpatient basis under local anesthesia.”

According to results from the Gax-Collagen Multicenter Trial, the ideal candidate for injectables has:

* poor urethral function (ISD)

* no detrusor overactivity

* adequate bladder capacity

* good anatomic support

* no urethral hypermobility

While early data with injectables “...suggest the injection process is adequate and patient satisfaction and QOL scores are comparable to surgery,” said Dr. Winters, over the long-term, the durability of collagen declines. Some 12-40% of patients will need re-injection within two years, and in Dr. Winters’ experience, only 40% of those who undergo re-injection achieve the same original success.

He also pointed out that the probability of maintaining dryness at 1 year is 52% and this declines to 38% at two years. Long-term implantation with another injection agent, macroplastique, also shows a marked decline in success, from 68-75% to 48% at 17 months to 2 years.

“Existing data show that cure/dry rates with injectables are not as good when compared to minimally invasive sling techniques,” said Dr. Winters. “The cost of repeat injections and continued need for undergarments after collagen makes it more expensive than AUS.”

Injection techniques also vary surgeon to surgeon, making reproducibility low. Further, collagen is not an ideal agent, thanks to cost and long-term safety issues such as migration, sterile abscesses, detrusor overactivity and urinary retention, noted Dr. Winters.

In presenting her case for the use of injectables as a first-line treatment for SUI, Dr. Dee Fenner pointed out that women with Intrinsic Sphincter Deficiency (ISD) have a high failure rate with urethral support operations—50% versus 15% when ISD is not present.

The urethral vesical junction, when open, is a predictor of ISD, noted Dr. Fenner, who is associate professor and director, division of gynecology, department of obstetrics and gynecology, University of Michigan, Ann Arbor, MI

There are more than 300 surgeries described for ISD. What is it and why is it important? asked Dr. Fenner. “ISD is a concept made into a diagnosis,” she told delegates. “It’s tied up with our technology and treatment strategies and is responsible for many operative failures.”

The concept is that poor function of the vesical neck sphincter can cause SUI despite normal support, she added. Tests for ISD include a Q-tip angle of 30 degrees or less; leak point pressure of below 60; and urethral closure pressure of below 20.

What exactly does collagen do? “We thought we were going to be closing up the bladder neck with some kind of obstruction,” said Dr. Fenner. She cited a study by Monga and Stanton (Br J Obstet Gynaecol 1997; 104: 158-62) which suggests, however, that periurethral collagen injection works because it prevents the bladder neck from opening during stress.

Collagen injection for ISD provides a bulking agent for a gaping vesical junction, but the collagen does begin to degrade in about 12 weeks, noted Dr. Fenner, adding that neovascularization and deposition of fibroblast and host collagen occurs within the implants. Patients for whom collagen injection is contraindicated include those with untreated UTI, unmanaged DI, and hypersensitivity to collagen, she said.

Evidence in the literature in favour of periurethral collagen injection includes a study by Richardson et al (Urology 1995: 46: 378-81) in 42 women treated for ISD. In that study, 83% were cured or improved at a mean followup of 46 months, noted Dr. Fenner. The median number of treatments was two and the mean amount injected for 28.3 cc.

Similarly, a study by Monga et al, (Br J Urol 1995; 76: 156-60) in 60 patients with a mean age of 60 years revealed a subjective and objective success rate at 24 months of 68% and 48%, respectively. There was a mean of 1.6 collagen injection sessions and a mean total of 19 ml of collagen injected per patient.

Finally, in a study by Hershcorn et al (J Urol 1996;156: 1305-9) of periurethral collagen injection in 187 women with a mean age of 63 years, a KM survival curve showed the probability of remaining dry was 71%, 58% and 46% at 1 to 3 years. The mean volume per session was 3.8 cc and the mean number of sessions was 2.5 in successful cases.

What about the woman in her early to mid-50s? asked Dr. Winters. Is an injectable a viable option to offering a mid-urethral sling? “While injectables fit in nicely for a number of women, particularly those with mixed incontinence,” he said, “for the 50-something women with urethral hypermobility and stress incontinence, we don’t know the answer.”