The artificial urinary sphincter (AUS) has been used since 1972 to treat severe urinary incontinence [1] and to date the AMS800 AUS (Boston Scientific) is still the most widely used device. Although AUS implant surgery has proven to be a reliable clinical option for male non-neurogenic incontinence, it is clear that robust scientific data about its exact efficacy, complication profile and long-term patient satisfaction rates are still lacking.

In this study we want to share our 30-year experience with AUS implants in a tertiary referral center. We retrospectively analyzed implant survival and revision-free survival. Long-term functional outcomes and patient satisfaction were evaluated. Also, for all outcomes we wanted to identify potential risk factors for failure.

All patients who underwent artificial urinary sphincter implant for non-neurogenic stress urinary incontinence between June 1989 and January 2020 were included in this single-centre retrospective consecutive series. Both primary and secondary implants were included. 

All implants were AMS 800® (Boston Scientific) and performed by two experienced surgeons.  A perineal approach with placement of a bulbar cuff was performed in nearly all cases. Through a separate inguinal incision, a 61-70 cmH2O abdominal reservoir was implanted. Standard antibiotic prophylaxis was given. Sphincters were deactivated at the end of the surgery. Standard follow-up protocol was activation of the device after six weeks and a first office evaluation after 2 to 3 months. Thereafter, follow-up was on an as-needed basis. 

Patient characteristics, peri-operative data, complication and revision rate were analyzed retrospectively. In April 2020, all patients with a functional artificial urinary sphincter in situ were contacted to evaluate long-term functional outcomes using standardized, validated questionnaires. Logistic regression models were used to identify risk factors for revision surgery, persistence or recurrence of incontinence and patient dissatisfaction.

A total of 263 patients were included in this retrospective series with a mean follow-up of 61 months. The median patient age was 69 years. 86.7% of the patients became incontinent due to radical prostatectomy.  We registered 22 early postoperative complications (5 retentions, 12 scrotal hematomas, 1 infection, 2 wound problems and 2 hematuria cases). A total of 294 sphincters were implanted; 249 patients received one implant, 40 patients received a second implant and 5 patients underwent a third AUS implant. Of these implants, 71 (24.2%) were again explanted.  Explants were mainly due to urethral erosions (51%) and infection (39%). Explant-free survival after 5 years was 75.3% (CI 68.8% - 80.7%)  with a median time to explant of 16.2 years (CI 12.2 – 28.1). A total of 73 patients (24.8%) underwent revision or maintenance surgery. Overall revision-free implant survival was 62.1% (CI: 55.0%-68.4%) after 5 years with a median revision-free implant survival rate of 10.8 years (Figure 1). Previous pelvic irradiation,  a history of stricture disease and previous artificial urinary sphincter implants were independent risk factors for decreased implant survival.  Overall social continence rate (i.e. needing no more than 1 pad/day) after 5 years was 60.3% (CI: 53.2% - 66.7%) and after 10 year social continence rate decreased to 37.9% (CI: 30.1% - 45.6). The median time to becoming socially incontinent was approximately 7 years (CI: 5.7-9.2) (Figure 2).  Prior radiation therapy, anticoagulation therapy, previous AUS implant and other previous anti-incontinence surgery were associated with a higher incontinence risk. In April 2020, a total of 142 patients (54% of the total population) with a functional AUS in situ agreed to complete validated quality of life and incontinence questionnaires.  Socially dry rate in this patient group was about the same as in the overall population (i. e. 51.4%). Of these patients, 92.3%, stated they were satisfied having undergone AUS implant surgery. Interestingly, a higher bladder capacity (each hundred milliliters increase of cystometric bladder capacity) was associated with being satisfied (HR 0.6; CI 0.4-0.9; p=0.02).  Patients who were completely incontinent before AUS implant were significantly more satisfied than other patients (HR 0.1; CI 0.0-0.7; p=0.02).

In our series, 60.3% (CI: 53.2% – 66.7%) of patients were socially continent 5 years after AUS implant and this number decreased to 37.7% (CI: 30.1% - 45.6%) at 10-year follow-up.  In the subset of patients with a functional AUS in situ that were contacted to complete the incontinence- and quality of life questionnaires (n=142), socially dry rates were similar as in the general study population (i.e. 52% with a mean follow-up time of 73 months) but, interestingly, patient satisfaction rates were remarkably high and reached 97.9% (CI: 94.2%-99.8%) at 5 years of follow-up and 87.5% (CI: 76.0%-93.7%) after 10 years. It seems that long-term continence rates after AUS implant are acceptable (but not great) and that patients should be carefully informed about a significant time related decline in continence. On the other hand, long-term patient satisfaction rates remain high.

Already a significant amount of data is available in literature evaluating implant survival and revision-free implant survival.  Our results show a revision-free implant survival of 62% at 5 year follow-up and 49% after 10 years, while overall implant survival is, respectively, 75% and 65%. Interestingly, patients who had a prior AUS and received a first-in-our-centre AUS had a significantly worse implant survival. Based on these findings, patients who are being offered AUS surgery, should be realistically counseled about their significant reintervention/maintenance or explant risk.

In literature, controversy still remains regarding the impact of previous pelvic irradiation on implant survival and continence rates. In our cohort almost half of the patients received prior pelvic radiotherapy which is a fairly high proportion of patients compared to other similar studies.  In univariate analysis (but not in multivariate analysis) prior pelvic radiation therapy was a risk factor for AUS explant (HR 1.9; CI:1.11-3.36; p=0.02) and not achieving social continence (HR 1.73; CI:1.19-2.49; p=0.003).  
In our study, urethral stricture disease and previous AUS implants also seem to compromise AUS survival. Interestingly, patients receiving anticoagulation therapy in our cohort were at increased risk for AUS explant (HR 1.7; CI 1.0-2.9; p=0.04) and anticoagulation therapy also proved to be an independent risk factor for social continence (HR: 0.6; CI: 0.4-0.9; p<0.01) and patient satisfaction (HR 3.9; CI 1.6-13.0; p=0.03). To our knowledge no other previous studies report this association although its exact underlying mechanism remains elusive. Interestingly, patients with pre-operative total incontinence were more likely to be satisfied with their long-term continence outcome (HR 0.12; CI 0.02 - 0.73; p=0.02), probably because a greater continence improvement is achievable in these patients. 

Although retrospective of nature, we believe these results can especially contribute to an improved understanding of long-term complication and revision profile, long-term social continence and patient satisfaction rates and thus will prove useful to guide everyday clinical practice.

A significant proportion of patients undergoing artificial urinary sphincter implant for male non-neurogenic stress incontinence needed revision or explant surgery. Long-term continence rates are acceptable but tend to decrease by time. Nonetheless, if patients can maintain a functional AUS in situ, long-term patient satisfaction rates remain high.

Scott FB, Bradley WE, Timm GW. Treatment of urinary incontinence by an implantable prosthetic urinary sphincter. J Urol 1974;112:75–80. https://doi.org/10.1016/s0022-5347(17)59647-0.