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
Authors: Hilton Paul , Armstrong Natalie , Brennand Catherine , Howel Denise , Shen Jing , Bryant Andrew , Tincello Douglas G , Lucas Malcolm G , Buckley Brian S , Chapple Christopher R , Homer Tara , Vale Luke , McColl Elaine ,   on behalf of the INVESTIGATE studies group
Published: February 2015

Background

The position of invasive urodynamic testing in the diagnostic pathway for urinary incontinence (UI) is unclear. Systematic reviews have called for further trials evaluating clinical utility, although a preliminary feasibility study was considered appropriate.

Objectives

To inform the decision whether or not to proceed to a definitive randomised trial of invasive urodynamic testing compared with clinical assessment with non-invasive tests, prior to surgery in women with stress UI (SUI) or stress predominant mixed UI (MUI).

Design

A mixed-methods study comprising a pragmatic multicentre randomised pilot trial; economic evaluation; survey of clinicians’ views about invasive urodynamic testing; qualitative interviews with clinicians and trial participants.

Setting

Urogynaecology, female urology and general gynaecology units in Newcastle, Leicester, Swansea, Sheffield, Northumberland, Gateshead and South Tees.

Participants

Trial recruits were women with SUI or stress predominant MUI who were considering surgery after unsuccessful conservative treatment. Relevant clinicians completed two online surveys. Subsets of survey respondents and trial participants took part in separate qualitative interview studies.

Interventions

Pilot trial participants were randomised to undergo clinical assessment with non-invasive tests (control arm); or assessment as controls, plus invasive urodynamic testing (intervention arm).

Main outcome measures

Confirmation that units can identify and recruit eligible women; acceptability of investigation strategies and data collection tools; acquisition of outcome data to determine the sample size for a definitive trial. The proposed primary outcome for the definitive trial was International Consultation on Incontinence Modular Questionnaire (ICIQ) Female Lower Urinary Tract Symptoms (ICIQ-FLUTS) (total score) 6 months after surgery or the start of non-surgical treatment; secondary outcomes included: ICIQ-FLUTS (subscales); ICIQ Urinary Incontinence Short Form; ICIQ Lower Urinary Tract Symptoms Quality of Life; Urogenital Distress Inventory; EuroQol-5D; costs, quality-adjusted life-years (QALYs) and incremental cost per QALY, Short Form 12; 3-day bladder diary.

Results

Of 284 eligible women, 222 (78%) were recruited; 165/219 (75%) returned questionnaires at baseline and 125/200 (63%) who were sent questionnaires at follow-up. There were few missing data items in returned questionnaires, with individual outcome scales calculable for 81%–94%. Most women underwent surgery; management plans were changed in 19 (19%) participants following invasive urodynamic testing. Participant Costs Questionnaires were returned by 53% 6 months after treatment; complete data to undertake cost–utility analysis were available in 27% (intervention) and 47% (control). While insufficient to recommend changes in practice, the results suggest further research would be valuable. All clinicians responding to the survey had access to invasive urodynamic testing, and most saw it as essential prior to surgery in women with SUI with or without other symptoms; nevertheless, 70% considered the research question underlying INVESTIGATE important and most were willing to randomise patients in a definitive trial. Participants interviewed were positive about the trial and associated documentation; the desire of some women to avoid invasive urodynamic testing contrasted with opinions expressed by clinicians through both survey and interview responses.

Conclusions

All elements of a definitive trial and economic evaluation were rehearsed; several areas for protocol modification were identified. Such a trial would require to 400–900 participants, depending on the difference in primary outcome sought.

Future work

A definitive trial of invasive urodynamic testing versus clinical assessment prior to surgery for SUI or stress predominant MUI should be undertaken.

Trial registration

Current Controlled Trials ISRCTN71327395.

Funding

The National Institute for Health Research Health Technology Assessment programme.