Midurethral slings for women with stress urinary incontinence: an evidence-based analysis.
OBJECTIVE
The objective of the current review was to evaluate the safety, efficacy, and cost-effectiveness of midurethral slings compared with traditional surgery.


BACKGROUND
This assessment was undertaken in order to update and expand upon the health technology & policy assessment of tension-free vaginal tape (TVT, Gynecare Worldwide, a division of Ethicon Inc, a Johnson & Johnson company, Somerville, New Jersey) sling procedure for stress urinary incontinence published by the Medical Advisory Secretariat in February 2004. Since the publication of the 2004 assessment, a number of TVT-like sling alternatives have become available which employ the same basic principles as TVT slings: minimally invasive, midurethral placement, self-fixing, and tension-free. This update will evaluate the efficacy and safety of midurethral slings.


OBJECTIVE
Normal continence is controlled by the nervous system and involves co-ordination between bladder, urethra, urethral sphincter, and pelvic floor. Incontinence occurs when the relationship among the above components is compromised, either due to physical damage or nerve dysfunction. (1) Stress urinary incontinence is the most common form of urinary incontinence in women. It is characterized by the "complaint of involuntary leakage on effort or exertion, or on sneezing or coughing" when there is increased abdominal pressure without detrusor (bladder wall) contraction. (2) There are 2 factors which define stress urinary incontinence: a weakening in the support of the proximal urethra, causing urethral hyper-mobility and deficiency in the sphincter, causing urethral leakage. Both factors are thought to coexist. (1) Accurate tests are not available to distinguish these 2 types of stress urinary incontinence. Urinary incontinence is estimated to affect about 250,000 Canadian women and 8 million American women aged 65 and over. (3;4) The prevalence of stress urinary incontinence is very difficult to measure because women with stress urinary incontinence may not tell their health practitioner about their symptoms due to embarrassment associated with stress urinary incontinence. A cross-sectional postal survey of 15,904 adults aged 40 and over who were registered with a local GP in Leicestershire, United Kingdom, revealed that 18% to 34% of respondents had symptoms of SUI. (5) Just over 9% reported symptoms "sometimes," while almost 3% reported symptoms "most of the time." Stress urinary incontinence was most common for women in their 50s. A more recent study suggests that 24% of women aged 18 to 44 years and 37% of women aged 45 and over have symptoms of stress urinary incontinence. (6) Stress urinary incontinence has been associated with a broad range of psychosocial stress and disablement, such as difficulties with activities of daily living, avoidance of social activities, fear of unpleasant odour, and embarrassment. (7) Economic burden may include the cost of pads, drugs, and devices, and the inability to participate in the work force in severe cases.  MIDURETHRAL SLINGS: Suburethral slings differ according to several criteria including placement, approach, method of fixation, and sling material. This review will evaluate slings which fulfill all of the following criteria: Midurethral placement (as opposed to bladder neck placement)Self-fixing (no sutures, bone anchors, etc.)Minimally invasive (using local, epidural, or general anesthesia)"Tension-free" placementThe different types of midurethral slings available vary according to 3 main parameters: Implant material, i.e., monofilament, multifilament, elastic, non-elastic, smooth, serrated, etc.,Delivery instruments, i.e., needles, curved trocars, disposable, reusable, etc.,Surgical approachAs any one, or any combination of these parameters may vary across the different sling brands, it is difficult to ascribe observed differences in efficacy and safety across slings to any one factor.


METHODS
The literature published between January 2000 and February 2006 was searched in the following databases: OVID Medline, In Process and Other Non-Indexed Citations, Embase, Cochrane Database of Systematic Reviews and CENTRAL, INAHTA. The database search was supplemented with a search of relevant Web sites, and a review of the bibliographies of selected papers. The search strategy can be viewed in Appendix 1.


METHODS
General population with SUIRandomized controlled studies, health technology assessments, guidelinesFemale subjectsMidurethral, self-fixing, and minimally invasive slings/tapesEnglish languageThe search strategy yielded 391 original citations. Studies were excluded for a variety of reasons, such as using traditional, suburethral slings as opposed to midurethral slings, not including patients with stress urinary incontinence, including males in the study, case reports, and not reporting the outcomes of interest. There were 13 randomized controlled trials identified that compared midurethral slings to other midurethral slings or traditional surgery. (8-20) (Table 1) Three of the randomized controlled trials (15;17;20) have had subsequent updated articles of longer term results. (21-23) The results of the randomized controlled trials have been stratified into 2 groups: TVT versus colposuspension and comparisons of midurethral slings. No randomized controlled trials were identified that compared a midurethral sling other than TVT to colposuspension.


RESULTS



RESULTS
At this time, there does not appear to be one procedure that is more effective than another at curing stress urinary incontinence. TVT appears to have similar cure rates to open colposuspension; and the various midurethral sling types seem to have similar cure rates.  PROCEDURE TIME AND LENGTH OF HOSPITAL STAY: The procedure time and the length of hospital stay for TVT are significantly shorter than the procedure time and length of stay for colposuspension. The procedure time and length of hospital stay for all midurethral slings appears to be similar.


RESULTS
The most frequently reported complications were bladder perforations, de novo voiding difficulties and device problems.
Quality of life was not consistently reported in all of the randomized controlled trials. In the studies that reported quality of life there does not appear to be a significant difference in quality of life scores between the sling procedures.