Hypothesis / aims of study
In our unit Urethral Bulking Agents (UBA) have traditionally been offered as salvage procedures for Stress Urinary Incontinence (SUI). Current guidance (1) favours them as a second line option based on expert opinion, however, with growing concerns about mesh-tapes, more women have opted for UBA as a primary procedure. Our aim was to compare the success of UBA in patients that had undergone a previous procedure for Stress Urinary Incontinence (salvage-UBA) to the SUI surgery naïve (primary-UBA).
Study design, materials and methods
Patients having their first UBA treatment (2010–2018) were identified prospectively on departmental audit databases. Trakcare ® electronic notes were then reviewed retrospectively. We have taken a Maximum Urethral Closure Pressure (MUCP) of ≤30cm H20 as an indicator of Intrinsic Sphincter Deficiency (ISD).
UBA were offered under local anaesthesia. Women underwent an initial treatment with a follow-up appointment at 3-months, where they were offered a further ‘top-up’ treatment. Voiding was assessed prior to discharge. Satisfactory voiding was achieved if residual bladder scan volumes were <150ml. Patients with voiding dysfunction, were either taught Clean Intermittent Self Catheterisation (CISC) and discharged, or admitted for intermittent drainage if they were unable to perform CISC.
Primary outcome was patient reported improvement on a 4-point scale: ‘cured, improved, no change, worse’ as utilised on the British Society of Urogynaecologists audit database. Treatment ‘success’ was defined as ‘cured’ or ‘improved’.
Secondary Outcomes included: investigative results, ‘top-up’ injection requirement, complications, duration of treatment success and further management. Paired and Unpaired t-tests were used to calculate p-values for assessing significant differences.
170 patients were identified over this time period: 132 primary-UBA and 38 salvage-UBA. There has been a four-fold rise in the number of procedures performed since 2010 (Fig. 1). In 2012, almost half (47%) of all UBA were salvage-type, whilst in the last year the majority (92%) were primary. Average age was 59 years and was the same in both groups. A statistically significantly higher BMI was noted in the salvage group (34.9 versus 30.2 p=0.007*).
Complete follow-up was obtained for 114 patients (n= 28 Salvage, n= 86 Primary). Median follow-up time was 20 months.
Initial success at follow-up following 1st injection was 10% higher in salvage-UBA than primary-UBA; 76% versus 66.3% respectively (Table 1).
Similar top-up rates were seen; 14%(n=4) versus 15%(n=13) respectively for both groups. Despite initial success, 36% (n=10) of salvage-UBA versus 26% (n=22) of primary-UBA required a 2nd treatment course when initial injections wore off. Median time to 2nd treatment course was 11.5 months with salvage-UBAs and 10 months with primary-UBAs
The mean MUCP was lower in the salvage group (36.5cmH20, n=21) than in the primary group (46.1cm H20, n=32). This was not statistically (p=0.092) significant, however, when patient reported outcomes were assessed based on MUCP ≤30cm H20; success was 60%. This rose to 68% with MUCP >30cmH2O. Urinary retention rates were higher in the salvage-UBA group (21% versus 14%). The median duration of CISC use was 3 days (range 1-14 days).
20 patients proceeded to alternative SUI surgery: These were more common following salvage procedures (38%) than primary procedures (25%).
Interpretation of results
UBA offer a success rate of 66% for primary versus 76% salvage-UBA suggesting benefit in both but higher initial success for the salvage group. The complication rate for urinary retention is 7% higher in salvage-UBA, however is short-lived with median duration of catheter use just 2-3 days. Salvage-UBA did tend to lose their effect over time with 36% proceeding to have a 2nd treatment course and 38% choosing an alternative surgical procedure.