600 women were randomised, 300 per group. The participant mean age was 47.7 years (SD 11.5), and 61.3% had MUI. The trial group characteristics were well-balanced at baseline. Adherence (fully explored in the process evaluation) was comparable between groups in terms of appointment attendance and undertaking the home programme.
Questionnaire response rates at 6 months, 1 and 2 years were 74%, 83%, 77% in the biofeedback PFMT group and 74%, 85%, 79% in the PFMT group. Primary outcome data were available for 460 participants (225 biofeedback PFMT and 235 PFMT). There was no significant difference between the groups in the ICIQ-UI SF score at 2 years (mean for biofeedback PFMT 8.2 (SD 5.1) and PFMT 8.5 (SD 4.9); mean difference -0.09, 95% CI -0.92 to 0.75) (see Table). The results of planned sensitivity analyses produced very similar findings under different assumptions about non-compliance with the intervention and missing data (results not shown). There were no significant subgroup interactions: the treatment effect between groups did not appear to differ by age, UI type, UI severity or therapist type (results not shown). There were no differences between groups in the ICIQ-UI SF score at 6 months (mean difference 0.39, 95% CI -0.33 to 1.12) and 1 year (mean difference 0.57, 95% CI -0.17 to 1.31) (see Table).
Participant reported improvement: At 2 years there was no significant difference between groups in the PGI-I score (OR 1.14, 95% CI 0.75 to 1.72), with 41% (biofeedback PFMT) and 38% (PFMT) reporting they were “very much better” or “much better”.
Exercise adherence: At 2 years, the proportion exercising at least once a week was 52.0% in the biofeedback PFMT group and 46.3% in the PFMT group (OR 1.20 95% 0.83 to 1.74, from post-hoc analysis).
Pelvic floor muscle contraction strength: There was no difference between the groups in the Oxford Score for slow contraction strength at 6 months (OR 1.28, 95% CI 0.86 to 1.89, p=0.22), with 43.8% (biofeedback PFMT) and 39.7% (PFMT) scoring 4 or 5 out of 6.
Uptake of further treatment: By 2 years, similar proportions of women had received surgery for UI (12.3% biofeedback PFMT, 9.3% PFMT, OR 1.25, 95% CI 0.35 to 4.46). Uptake of further non-surgical care/treatment for UI was also comparable between groups (81.7% biofeedback PFMT, 79.7% PFMT, OR 1.35, 95% CI 0.54 to 3.41).
Cost-effectiveness: Biofeedback PFMT was not significantly more expensive than PFMT alone and did not generate significantly higher QALYs. The incremental cost-effectiveness ratio (ICER) was £56,617. The probability that biofeedback PFMT would be cost-effective was 48% and 49% at £20,000 and £30,000 thresholds for willingness to pay (WTP) for a QALY.