Hypothesis / aims of study
Most electrical muscle stimulation devices for the treatment of stress urinary incontinence use transvaginal electrical stimulation. The Vital Compact is a novel, non-invasive, external electrical muscle stimulation device for the treatment of incontinence. It comprises a portable, handheld, battery-powered controller connected to a 2-part wrap-around garment which holds hydrogel adhesive skin-contact electrodes in place on the buttocks and thighs. The aim of this study was to compare the efficacy and safety of the Vital Compact external electrical muscle stimulation device with an FDA-cleared intravaginal device (itouch sure) for the treatment of stress urinary incontinence in women.
Study design, materials and methods
This was a prospective, randomized, single-blind, multicenter, noninferiority study performed at 12 sites in the USA. Women with stress urinary incontinence whose condition had not improved using pelvic floor muscle training (Kegel exercises) were randomized to undergo treatment with either the Vital Compact or itouch sure device for 12 weeks. Treatment was administered by the subjects at home using the device in accordance with the relevant instructions for use, which specified that the Vital Compact device was used for 30 minutes once daily for 5 days/week, and the itouch sure device was used for 20 minutes once daily every day.
The primary endpoint was the proportion of subjects who achieved “significant improvement” (>50% reduction in pad weight from baseline) in the provocative pad weight test at 12 weeks. Key secondary efficacy endpoints included the mean change from baseline to week 12 for urine leakage in the provocative pad weight test and the 24-hour pad weight test, number of incontinence episodes/day, Incontinence Quality of Life questionnaire (I-QOL) score, number of pads used/day, and the proportion of patients achieving dryness (<1 g on the provocative pad weight test) at week 12. These endpoints were to be analysed in hierarchical fashion, provided the primary endpoint was met. Safety and tolerability were also assessed. The study sample size was 180 patients: assuming a success rate of 52% for the itouch sure  and 71% for the Vital Compact, 87 subjects/group provided 90% power using a one-sided type I error rate of 0.025 and a noninferiority margin of 5%.
Between April 2015 and April 2017, 89 women were randomized into the Vital Compact group and 91 to the itouch sure group. Baseline incontinence characteristics were similar between the groups (table).
At week 12 a “significant improvement” in the provocative pad weight test was seen in most subjects in both the Vital Compact group (56.3%) and the itouch sure group (63.0%), although noninferiority was not established because the lower bound of the 95% confidence interval for the treatment difference did not exceed the -5% noninferiority margin (difference 6.7%, 95% CI 21.7% to 8.4%). Nonetheless, statistically significant improvements from baseline in mean urine leakage in the provocative pad weight test and 24-hour pad weight test, number of incontinence episodes and pads used per day, and I-QOL score were seen with both devices at week 12 (table). In accordance with the prespecified hierarchical statistical analysis plan between-group differences were not tested statistically, but there were no clinically significant differences in the level of improvement seen in the two groups. At week 12, 87.2% of the Vital Compact group and 86.8% of the itouch sure group were in the dry or mild categories of stress incontinence severity, compared to 54.5% and 60.7% at baseline (all of which had been in the mild category), representing an improvement of 32.7% for Vital Compact and 26.1% for itouch sure.
A higher proportion of the Vital Compact group than the itouch sure group used the device for ≥75% of target use (81.6% versus 67.0%) and mean±SD percent target use was higher in the Vital Compact group (86.25±28.75%) than in the itouch sure group (76.50±25.029%). Adverse events were predominantly mild or moderate. No serious device-related adverse events occurred. Few subjects discontinued the study due to adverse events (Vital Compact 3.4%, itouch sure 4.4%) and only 2 subjects, both in the Vital Compact group, discontinued due to device-related adverse events (device discomfort, skin irritation). The most common device-related adverse event with the Vital Compact was device discomfort (9.0%); in most cases this was managed by modifying the stimulation intensity. The most common device-related adverse events in the itouch sure group were urinary tract/vaginal infections (7.7%); no infections occurred in the Vital Compact group.
Interpretation of results
The two devices provided broadly similar, clinically meaningful, improvements in a range of subjective and objective measures of stress urinary incontinence. Noninferiority versus the itouch sure was not established for the primary endpoint, possibly in part because of underpowering. Both devices were well tolerated. The Vital Compact was associated with fewer infections than the itouch sure. Compliance with treatment appeared to be better with the Vital Compact