SNM is an established therapy for refractory overactive bladder (OAB) and non-obstructive urinary retention (NOUR), with evidence supporting its long-term effectiveness. However, maintenance of the therapy can be limited by adverse events (AEs) which are under-reported. We report the long-term outcomes of SNM following a structured management protocol, with the aim to optimise and sustain the therapy.
This is a prospective, real world, single-centre cohort study of patients with OAB or NOUR who received permanent SNM (Medtronic and Axonics) after a successful tined-lead trial (Jan 2013–Dec 2022). AEs included return of symptoms and complications (battery site pain, lower limb pain and infection). Management protocol included reprogramming (basic, advanced, and salvage) and operations (battery-site local anaesthetic and steroid injection; battery re-siting and explantation). Primary outcome was therapeutic success, defined as 50% or greater clinical improvement from baseline symptoms; secondary outcomes were cumulative incidences of AE and reoperation, and success rates of management. Kaplan–Meier survival and multivariable Cox regression analyses were performed with missing data imputed.
Of 579 patients trialled, 400 (69%) received permanent SNM (OAB, n= 208; NOUR, n= 192). The median follow-up was 6.3 (IQR: 3.7-8.4) years. The 8-year therapeutic success was 52.3% (95% CI: 46.5–68.8%), although devices were explanted in 165 (41%) at median of 8.4 (IQR: 7.5-10.2) years. The 8-year incidences of AE and reoperation were 82.5% and 57.0% respectively with no significant difference between OAB and NOUR groups. (Figure 1) Male gender was the only risk predictor of AE (HR 0.68, 95%CI: 0.49,0.94, p=0.018), whereas age, maximal urethral closure pressure, detrusor overactivity, bladder capacity, post-void residual did not predict therapeutic success or AE. Success rates were 44%, 33%, and 21% for basic, advanced, and salvage reprogramming; 71% for battery re-siting, and 58% for local anaesthetic and steroid injection.
Eight years following implant, over half of the LUTD patients successfully maintained SNM benefit; 4 in 5 patients experienced at least one AE; and 1 in 2 required reoperation. A structured management protocol significantly improves SNM long-term effectiveness.
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