CATHETER II: a randomised controlled trial comparing the clinical effectiveness of various washout policies versus no washout policy in preventing catheter-associated complications in adults living with long-term catheters

Objectives: Do weekly prophylactic saline or acidic catheter washouts in addition to standard long-term catheter (LTC) care improve the outcomes of adults with LTC compared with standard LTC care only.

Design: Three-arm superiority open-label randomised controlled trial.

Setting: UK community-based study.

Participants: 80 adults with LTC (any type/route) ≥28 days in situ with no plans to discontinue and able to self-manage the washouts/study documentation with/without a carer.

Interventions: Randomly allocated (26:27:27) to receive standard LTC care with weekly saline or weekly acidic or no prophylactic washouts for up to 24 months.

Primary and secondary outcome measures: The primary outcome was catheter blockage requiring intervention (per 1000 catheter days). Secondary outcomes were symptomatic catheter-associated urinary tract infection (S-CAUTI) requiring antibiotics, adverse events, participants' quality of life and day-to-day activities, acceptability and adherence.

Results: Outcomes reported for 25 saline, 27 acidic and 26 control participants. LTC blockages (per 1000 catheter days) requiring treatment were 9.96, 10.53 and 20.92 in the saline, acidic and control groups, respectively. The incident rate ratio (IRR) favours the washout groups (saline 0.65 (97.5% CI 0.24 to 1.77); p=0.33 and acidic 0.59 (97.5% CI 0.22 to 1.63); p=0.25), although not statistically significant. The S-CAUTI rate (per 1000 catheter days) was 3.71, 6.72 and 8.05 in the saline, acidic and control groups, respectively. The IRR favours the saline group (saline 0.40 (97.5% CI 0.20 to 0.80); p=0.003 and acidic 0.98 (97.5% CI 0.54 to 1.78); p=0.93). The trial closed before reaching target recruitment due to reduced research capacity during the COVID-19 pandemic.

Conclusions: Early closure and small sample size limits our ability to provide a definite answer. However, the observed non-statistically significant differences over control are favourable for lower rates of LTC blockages without a concomitant rise in S-CAUTI. The results support a multinational randomised controlled trial of catheter washouts in patients with LTC to ascertain their clinical and cost-effectiveness.

Trial registration number: ISRCTN17116445.