Synthetic sling or artificial urinary sphincter for men with urodynamic stress incontinence after prostate surgery: the MASTER non-inferiority RCT

Background: Stress urinary incontinence is common in men after prostate surgery and can be difficult to improve. Implantation of an artificial urinary sphincter (AUS) is the most common surgical procedure for persistent stress urinary incontinence, but it requires specialist surgical skills, and revisions may be necessary. The sphincter is relatively expensive and its operation requires adequate patient dexterity. New surgical approaches include the male synthetic sling, which is emerging as a possible alternative; however, robust randomised data comparing safety and efficacy with AUS are lacking. Objective: To compare the clinical effectiveness and cost-effectiveness of the male synthetic sling with AUS surgery in men with persistent stress urinary incontinence after prostate surgery. Design: Multicentre, non-inferiority randomised controlled trial (RCT), with a parallel non-randomised cohort (NRC) and embedded qualitative component. Allocation by remote web-based randomisation (1:1), minimised on previous prostate surgery (radical prostatectomy or TURP), radiotherapy (yes/no) and centre. Surgeons/participants were unblinded. NRC allocation followed participant/surgeon preference. Setting: 28 UK NHS urological centres. Participants: Men with urodynamic stress incontinence after prostate surgery deemed appropriate for surgery. Exclusions: prior sling/AUS, unresolved bladder neck contracture/urethral stricture, insufficient dexterity to operate AUS, inability to consent/complete documentation. Interventions: Male synthetic sling versus AUS. Main outcome measures: Clinical primary outcome: participant-reported continence at 12 months post randomisation (ICIQ-UI SF Q3 and Q4), non-inferiority margin 15%. Economic primary outcome: cost-effectiveness as incremental cost per QALY at 24 months post randomisation. Results: 380 men were randomised (190 per group); 99/100 were included in the NRC. The sling was non-inferior to AUS for continence at 12 months (ITT absolute risk difference -0.034, 95% CI -0.117 to 0.048; non-inferiority p=0.003). ICIQ-UI SF improved in both groups from baseline to 12 months (sling 16.1 to 8.7; AUS 16.4 to 7.5; mean difference at 12 months 1.30, 95% CI 0.11 to 2.49; p=0.032, favouring AUS). Serious adverse events were few (sling n=8; AUS n=15; one AUS participant had three SAEs). Quality-of-life improved and satisfaction was high in both groups; several secondary outcomes statistically favoured AUS. Reoperation within 24 months was more frequent after sling (10.5%) than AUS (2.1%); most sling revisions converted to AUS. Economic evaluation: slings cost less than AUS but yielded slightly fewer QALYs over 24 months (incremental cost -£2497, 95% CI -£3167 to -£1875; incremental QALYs -0.006, 95% CI -0.06 to 0.054). The ICER indicated a cost saving of £425,870 per QALY lost; probability that slings are cost-effective at a £30,000/QALY threshold was 99%. Long-term modelling showed reduced cost savings and greater QALY loss over time, lowering cost-effectiveness probability to 42% at 10 years. Limitations: Follow-up beyond 24 months not available. More specific surgical/device-related pain outcomes were not included. Conclusions: Continence rates and symptoms improved from baseline in both groups, with the sling non-inferior to AUS on the primary outcome. Overall, secondary and post hoc analyses tended to favour AUS. Both procedures were associated with high satisfaction and quality-of-life improvements. Slings were less costly over 24 months but with small QALY loss. Future work: Five-year follow-up on further surgery, satisfaction and quality of life; consider additional pain questionnaire. Trial registration: ISRCTN49212975. Funding: NIHR Health Technology Assessment programme; full report in Health Technology Assessment 2022;26(36).