INVESTIGATE-I (INVasive Evaluation before Surgical Treatment of Incontinence Gives Added Therapeutic Effect?): a mixed-methods study to assess the feasibility of a future randomised controlled trial of invasive urodynamic testing prior to surgery for stress urinary incontinence in women.

Urinary incontinence (UI), while rarely life-threatening, may seriously influence the physical, psychological and social well-being of affected individuals.(1-4) The impact on the families and carers may be profound and the resource implications for the health service considerable.(5) Prevalence figures for UI range from 5% to 69% in women aged 15 years and older, with most studies in the range 25-45%. 6 More severe UI is reported in 4-7% of women aged under 65 years, and around 5 million women over 20 years of age in England and Wales may be affected.(7) Although absolute prevalence rates vary widely, the distribution of UI subtypes appears more consistent, with stress UI (SUI) or mixed UI (MUI) accounting for 65-85% of cases.(8) Isolated SUI accounts for approximately half of all incontinence, with most studies reporting 10-39% prevalence; MUI is the next most common, with prevalence figures of 7.5-25.0%; isolated urgency UI appears to be relatively uncommon, with 1-7% prevalence.(6)