Study design, materials and methods
CATHETER II was a pragmatic three-arm open-label multi-centre superiority RCT with internal pilot and embedded qualitative component. The trial methodology was in accordance with CONSORT (Consolidated Standards of Reporting Trials) guidelines and the protocol has been published (1).
A community-based study in the UK recruiting from 21 centres in primary, community, and secondary care and remotely via targeted advertisements. 80 adults with LTC (any type/route) ≥28 days in situ and with no plans to discontinue and the ability to self-manage the washout and study documentation with or without the help of a carer. All 80 participants received standard LTC care and were randomly allocated (26:27:27) to receive weekly saline washouts or weekly citric acid washouts or no prophylactic washouts for up to 24 months.
The primary outcome was catheter blockage requiring intervention per 1000 catheter days. Secondary outcomes included symptomatic catheter-associated urinary tract infection (S-CAUTI) requiring antibiotics, adverse events, participants’ quality of life (QoL) and day-to-day activities, acceptability and adherence to intervention.
Results
Recruitment commenced in December 2019 and was paused in March 2020 due to COVID-19 pandemic regulations. Recruitment resumed in September 2020 and ended in August 2022. Follow up continued up to August 2023. Baseline Characteristics are detailed in Table 1. The mean (SD) age was 65 (17) with those in the control group slightly older and similar numbers of males and females in all three groups. LTC blockages (/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 [0.65(0.24 to 1.77); p-value=0.33 for saline washout and 0.59(0.22 to 1.63); p-value=0.25 for acidic washout], albeit these differences are not statistically significant. Similar results were obtained when the two washout groups were combined in a post-hoc analysis, IRR (0.62(0.26 to 1.49); p- value=0.22).
The S-CAUTI rate was 8/1000 catheter days (control) and 6.72/1000 (acidic washout), IRR 0.98(0.54 to 1.78); p-value=0.93; and 3.71/ 1000 (saline washout), IRR 0.40(0.20 to 0.80); p- value=0.003. Refer Table 2 for detailed results of the outcomes; blockage requiring treatment and S-CAUTI.
Participants in both washout groups had better QoL scores in EQ-5D-5L (0.056(-0.022 to 0.134); p-value=0.11 and 0.053(-0.024 to 0.131); p-value=0.12) and ICECAP-A (Adult version) (-0.076(-0.221 to 0.068); p-value=0.24 and -0.086(-0.214 to 0.042); p-value=0.13) than control. However, both findings were not statistically significant. Treatment satisfaction scores were generally high in both washout groups. The trial was terminated before reaching target recruitment (n=600) primarily due to COVID pandemic-related difficulties in recruitment of primary and secondary care centres with research capacity.
Interpretation of results
The early closure and small sample size of the CATHETER II RCT 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, improvement in QoL, day-to-day activities, acceptability of the prophylactic washouts with selfcare, without a concomitant rise in S- CAUTI.