Randomised Controlled Trial CompAring THE Clinical And CosT-Effectiveness Of VaRious Washout Policies Versus No Washout Policy In Preventing Catheter Associated Complications In Adults Living With Long-Term Catheters: study protocol for the CATHETER II study.

Abstract • Background Various washout policies are widely used in adults living with long-term catheters (LTC). There is currently insufficient evidence on the benefits and potential harms of prophylactic LTC washout policies in prevention of blockages and other LTC-related adverse events, such as urinary tract infections. CATHETER II tests the hypothesis that weekly prophylactic LTC washouts (normal saline or citric acid) in addition to standard LTC care reduces the incidence of catheter blockage requiring intervention compared to standard LTC care only in adults living with LTC.• MethodsCATHETER II is a pragmatic three-arm open multi-centre superiority randomised controlled trial with an internal pilot, economic analysis, and embedded qualitative study. Eligible participants are adults aged ≥18 years, who have had a LTC in use for ≥28 days, have no plans to discontinue the use of the catheter, are able to undertake the catheter washouts, and complete trial documentation or have a carer able to help them. Participants are identified from General Practitioner practices, secondary / tertiary care, community healthcare, care homes and via public advertising strategies. Participants are randomised 1:1:1 to receive a weekly saline (0.9%) washout in addition to standard LTC care, a weekly citric acid (3.23%) washout in addition to standard LTC care or standard LTC care only. Participants and/or carers will receive training to administer the washouts. Patient-reported outcomes are collected at baseline and for 24 months post-randomisation. The primary clinical outcome is catheter blockage requiring intervention up to 24 months post-randomisation expressed per 1000 catheter days. Secondary outcomes include symptomatic catheter-associated urinary tract infection requiring antibiotics, catheter change, adverse events, NHS/ healthcare use, and impact on quality of life. • DiscussionThis study will guide treatment decision-making and clinical practice guidelines regarding the effectiveness of various prophylactic catheter washout policies in men and women living with LTC. This research has received ethical approval from Wales Research Ethics Committee 6 (19/WA/0015).• Trial registration ISRCTN (ISRCTN17116445). Registered prospectively on 06 November 2019, https://doi.org/10.1186/ISRCTN17116445