SIMS: Single-Incision Mini-Slings versus Standard Midurethral Slings
SIMS was a pragmatic, open-label noninferiority trial in women undergoing primary sling surgery for stress-predominant urinary incontinence, comparing adjustable anchored Ajust or Altis single-incision mini-slings with retropubic or transobturator standard midurethral slings. Mini-slings met the prespecified noninferiority margin for patient-reported improvement at 15 months after randomization.[1]
- Design and population
- Multicenter noninferiority randomized trial. Women aged 18 years or older with predominant stress urinary incontinence after failed or declined conservative treatment; no previous SUI surgery, stage 2 or greater anterior/apical prolapse, or planned concomitant surgery.
- Arms
- Adjustable anchored single-incision mini-sling (Ajust or Altis) versus standard retropubic or transobturator tension-free midurethral sling
- Report and follow-up
- 2022 · Primary endpoint at 15 months after randomization (approximately 1 year after surgery); follow-up through 36 months after randomization.
| Endpoint | Results | Effect | Finding |
|---|---|---|---|
| Much or very much improved at 15 months; adjusted risk difference in percentage points | 212/268 (79.1%) vs 189/250 (75.6%) | difference 4.6; CI -2.7–11.8; P <0.001 for noninferiority | Met |
Harms: Dyspareunia at 36 months among women assigned direct questions: 17/145 (11.7%) vs 7/145 (4.8%); Tape or mesh exposure through 36 months: 9/276 (3.3%) vs 5/261 (1.9%); Groin or thigh pain at 36 months: 39/276 (14.1%) vs 39/261 (14.9%)
ISRCTN93264234 · Report DOI
Design
At 21 UK hospitals, 600 women were randomized; four post-randomization exclusions left 298 in each arm. Eligible women had failed or declined conservative treatment. Prior surgery for stress urinary incontinence, stage 2 or greater anterior or apical prolapse, predominant overactive bladder symptoms, and planned concomitant surgery were exclusions. The surgeon selected the specific device within the assigned strategy, and neither patients nor surgeons were blinded.[1][2]
The primary endpoint was a response of “much improved” or “very much improved” on the Patient Global Impression of Improvement (PGI-I) questionnaire at 15 months after randomization, approximately one year after surgery. The noninferiority margin was 10 percentage points. Cystoscopy and postoperative voiding assessment were specified for both arms; participating surgeons had experience with both approaches, and trial clinicians observed mini-sling procedures at most centers before recruitment.[1][2]
Results
PGI-I success at 15 months was 212/268 (79.1%) after a mini-sling and 189/250 (75.6%) after a standard sling: adjusted risk difference 4.6 percentage points (95% CI −2.7 to 11.8; P < 0.001 for noninferiority).[1] At 36 months, success was 177/246 (72.0%) and 157/235 (66.8%), respectively; adjusted risk difference 5.7 points (95% CI −1.3 to 12.8), also within the 10-point margin.[1][2]
Objective success on a 24-hour pad test, defined as less than 8 g gain, was 102/119 (85.7%) versus 83/110 (75.5%) at 15 months, with an adjusted risk difference of 5.2 percentage points (95% CI −5.9 to 16.2).[1] Only about 36% of participants completed the pad test, limiting this comparison.[2] In the companion NHS economic analysis through 36 months, mean cost was £1696 versus £1702 (adjusted mean difference −£6, 95% CI −£228 to £208), and mean quality-adjusted life-years were 2.347 versus 2.342 (difference 0.005, 95% CI −0.068 to 0.073).[1][2]
Surgery and treatment delivery
Among women who underwent surgery, 62/276 (22.5%) in the mini-sling arm received Ajust and 195/276 (70.7%) received Altis.[1][2] In the standard-sling arm, 119/261 (45.6%) received a retropubic tape and 138/261 (52.9%) a transobturator tape; the remaining procedures included crossovers.[1][2] Surgery was performed in 276/298 (92.6%) and 261/298 (87.6%), while 257/298 (86.2%) in each arm received the assigned procedure.[1][2]
Local anesthesia with or without sedation was used in 201/276 (72.8%) mini-sling operations and 16/261 (6.1%) standard-sling operations.[1] Cough stress testing guided intraoperative sling adjustment in 180/276 (65.2%) and 15/261 (5.7%).[1] Mean procedure time was 39.2 minutes (n=273) versus 41.3 minutes (n=258); the adjusted mean difference was −2.2 minutes (95% CI −5.9 to 1.6).[1] Cystoscopy was performed in both arms.[1][2]
Adverse events
At 36 months, groin or thigh pain was reported by 39/276 (14.1%) mini-sling recipients and 39/261 (14.9%) standard-sling recipients.[1] Tape or mesh exposure through 36 months occurred in 9/276 (3.3%) and 5/261 (1.9%); the risk difference was 1.3 percentage points (95% CI −1.7 to 4.4).[1][2] Further surgery for stress urinary incontinence occurred in 7/276 (2.5%) and 3/261 (1.1%), and any additional surgical treatment in 24/276 (8.7%) and 12/261 (4.6%).[1][2]
Among women assigned direct sexual-function questions, dyspareunia at 36 months was reported by 17/145 (11.7%) in the mini-sling arm and 7/145 (4.8%) in the standard-sling arm.[1] Baseline dyspareunia in this subgroup was 25/145 (17.2%) and 21/145 (14.5%), respectively.[1] Intraoperative bladder injury occurred in 0/276 (0%) and 9/261 (3.4%); self-catheterization at 36 months was reported by 3/276 (1.1%) and 4/261 (1.5%).[1][2]
Limitations
Surgeons chose among devices and routes within each assigned strategy, so this comparison pools Ajust and Altis against two standard sling routes. Anesthesia and cough-test adjustment also differed substantially between arms. Outcomes were unblinded and largely patient reported; the trial had limited power for uncommon harms and follow-up ended at 36 months.[1][2]
In conversation
Same setting TOMUS (2010)
The standard-sling arm combined retropubic and transobturator operations, while the mini-sling arm used predominantly Altis; the estimate describes those assigned strategies and their operative mix.[1]
Guidelines and approvals
- AUA/SUFU (2023 amendment, statement 13). For index patients selecting midurethral sling surgery, clinicians may offer a retropubic, transobturator, or single-incision sling .[3]
- EAU (2026 edition). Inform women offered Ajust or Altis that short-term efficacy appears equivalent to conventional midurethral slings , and inform women offered a single-incision sling that long-term efficacy remains uncertain .[4]
Report history
| Published | Report | Cutoff | Headline results | Citation |
|---|---|---|---|---|
| 2022-03-30 | Primary clinical report through 36 months · primary | — | Much or very much improved at 15 months; adjusted risk difference in percentage points: 212/268 (79.1%) vs 189/250 (75.6%); difference 4.6; CI -2.7–11.8; P <0.001 for noninferiority Met Much or very much improved at 36 months; adjusted risk difference in percentage points: 177/246 (72.0%) vs 157/235 (66.8%); difference 5.7; CI -1.3–12.8 Met Pad weight gain <8 g at 15 months; adjusted risk difference in percentage points: 102/119 (85.7%) vs 83/110 (75.5%); difference 5.2; CI -5.9–16.2 | Abdel-Fattah M, Cooper D, Davidson T, et al. Single-Incision Mini-Slings for Stress Urinary Incontinence in Women. *N Engl J Med.* 2022;386(13):1230-1243. DOI |
| 2022-12-01 | NIHR full trial and health economics report · secondary | — | Mean per-patient cost through 36 months; adjusted mean difference in GBP: £1696 vs £1702; difference -6; CI -228–208 Mean QALYs through 36 months; adjusted mean difference: 2.347 vs 2.342; difference 0.005; CI -0.068–0.073 | Abdel-Fattah M, Cooper D, Davidson T, et al. Single-incision mini-slings versus standard synthetic mid-urethral slings for surgical treatment of stress urinary incontinence in women: The SIMS RCT. *Health Technol Assess.* 2022;26(47):1-190. DOI |
References
1. Abdel-Fattah M, Cooper D, Davidson T, et al. "Single-Incision Mini-Slings for Stress Urinary Incontinence in Women." N Engl J Med. 2022;386(13):1230-1243. doi:10.1056/NEJMoa2111815
2. Abdel-Fattah M, Cooper D, Davidson T, et al. "Single-incision mini-slings versus standard synthetic mid-urethral slings for surgical treatment of stress urinary incontinence in women: The SIMS RCT." Health Technol Assess. 2022;26(47):1-190. doi:10.3310/BTSA6148
3. American Urological Association; Society of Urodynamics, Female Pelvic Medicine & Urogenital Reconstruction. Surgical Treatment of Female Stress Urinary Incontinence: AUA/SUFU Guideline (2023 amendment). Statement 13.
4. European Association of Urology. EAU Guidelines on Non-neurogenic Female LUTS. Limited update, March 2026. Section 4.2.4.c.2.