The clinical evaluation of women with UI includes patient history, physical examination and measures of incontinence severity. An understanding of those patient factors associated with treatment failure and success can help us more robustly counsel patients regarding realistic expectations from midurethral sling surgery for stress incontinence. In this analysis we hypothesized that objective and subjective outcome measures capture different post-operative processes and those that failed objectively may be a more “severe” failure or have a greater degree of failure. Objective measures may be a more sensitive reflection of the sling procedures mechanism of action, with the dynamic urethral kinking that occurs with the TVT serving as a fulcrum reflecting surgical technique and quality of host tissue in-growth. (20
) An understanding of the types of patients at risk for these types of failures may help us more effectively target patients for these or other treatment options. Subjective failures may capture urge symptoms, less severe leakage or other perceived leakage that may or may not be related to sling function in preventing SUI.
In our study, women who had prior UI surgery had nearly twice the odds of overall failure compared to women having their first surgery for SUI. Previous incontinence surgery as a risk factor for failure after MUS has been described by several authors (2
) and may be due to scarring, nerve damage during periurethral dissection, or more severe neuromuscular compromise. We observed that women with less urethral mobility (Q-tip max straining angle <30 ° had about twice the odds of overall failure than patients with more urethral mobility (Q tip angle ≥30 degrees) despite the fact that pre-operative urethral hypermobility was not associated with objective failure. Others have reported similar findings. (21
) For example, Liapis et al (21
) observed that women with a less mobile urethra (maximum Q-tip straining angle < 30°) undergoing TVT for recurrent SUI had a 50% failure rate compared to 10% failure rate in patients with greater mobility (Q-tip excursion ≥30°). Therefore, patients with less mobility may have a more neurologically impaired baseline urethral function and and other treatments such as bulking agents may be a more appropriate consideration.
For every 10 point increase in the baseline MESA urge incontinence score the odds of overall failure nearly doubled. In addition, for every 10 point increase in urge incontinence bother as measured by the UDI, the odds of objective failure increased by nearly 10%. We and others have also previously described this association. (23
) To this point, Holmgren reported the long-term cure rate after TVT in women with mixed urinary incontinence (MUI) was 30% at 8 years compared to an 85% cure rate in women with pure SUI.(24
) However, others have found the presence of urge symptoms in stress-predominant MUI does not negatively impact success. (25
) Whether patients with more urgency incontinence symptoms reflects a more complex neuromuscular dysfunction is not clear. Nonetheless, patients with MUI should be strongly counseled about the possibility of lower cure rates and perhaps more robust perioperative treatment with behavioral and/or medical therapy should be considered.
We found that greater pad weight at baseline increased the odds of both overall failure and objective failure after MUS and this has been corroborated by others.(2
) In the current study pad weight was the only clinical measure associated with both overall and objective surgical failure. Perhaps the use of pad testing should be used more frequently in the evaluation of our patients considering midurethral sling surgery for stress incontinence.
Concomitant prolapse surgery was not associated with overall failure, but did decrease the odds of objective as compared to subjective failure by nearly 50%. Similarly, a large retrospective study showed that concomitant pelvic organ prolapse (POP) surgery decreased the likelihood of failure of retropubic or transobturator MUS (3
). These data conflict with another study that reported concurrent POP surgery increased the odds of developing any recurrent incontinence.(1
Strengths of the study included its multicenter design including sites throughout the United States, with a variety of urology and urogynecology surgeons making our study more generalizable. We included extensive preoperative clinical and demographic variables, used clearly defined validated outcome measures and had a high rate of ascertainment at 12 month post-surgery. In the patient evaluation process for urinary incontinence, after obtaining the baseline clinical evaluation and examination, urodynamic testing is often used to confirm the diagnosis or provide additional functional and/or severity information. This current report only focuses on those demographic and clinical factors that may predict failure.
In conclusion, women with prior incontinence surgery, urethral hypomobility, and more severe urge urinary incontinence symptoms demonstrated greater overall odds of failure 12 months after undergoing RMUS or TMUS surgery. Pad weight testing seems to be a powerful predictor of failure. Although surgical history and urethral mobility are not modifiable risk factors, this information will assist in counseling patients regarding the efficacy of these procedures, help identify patients who may benefit from additional or alternate therapies and assist in setting appropriate expectations for women with increased odds for treatment failure.