Small study finds that hydrophilic catheters decrease use of antibiotics to treat UTI in people with spinal cord injury who use self-intermittent catheterisation compared with non-coated catheters
- 1Faculty of Nursing and Faculty of Medicine, University of Alberta, Alberta, Canada
- 2School of Health Sciences, University of Southampton, Southampton, UK
- Correspondence to Katherine N Moore
Faculty of Nursing and Faculty of Medicine, University of Alberta, Alberta T6G 2G3 Canada;
Although intermittent catheterisation is considered best practice for patients with neurogenic bladders and incomplete emptying, one major challenge for successful users is control of symptomatic urinary tract infections (UTIs). In addition to such consequences as days missed from school or work, visits to the laboratory, antibiotic use, risk of resistance and costs to the healthcare system, there is the possibility of upper tract damage resulting in renal impairment. Thus, products or methods that may reduce the incidence of UTIs need to be considered. Regional factors mean that some patients use sterile single-use disposable catheters and others reuse their catheters after washing them with soap and water. It would seem reasonable to assume that good technique and sterility of catheterisation are important in reducing UTIs. However, evidence is lacking to support sterile single-use over clean reused catheters.1 2
Attention has been paid recently to the potential for single-use hydrophilic catheters to reduce UTIs. Laboratory research suggests that compared with a PVC catheter, the hydrophilic coating protects against urethral irritation and results in less potential mucosal injury and foci for infectious organisms, but this research has not, as yet, translated into relevant clinical findings. One study suggested a reduced incidence of UTIs up to Day 15, but subject attrition was disappointingly high and further long-term benefits were not evident.3 Overall, the benefit of hydrophilic catheters or sterile single-use PVC catheters has not been proven because of small study sample sizes, attrition and short-term follow-up. The study by Cardenas and colleagues is a welcome supplement to the current evidence and will be added to the next update of the Cochrane review.
Cardenas and colleagues compare the incidence of symptomatic UTIs between users of single-use PVC catheters and users of single-use hydrophilic coated catheters. Necessary sample size was calculated at 30 per group, so the researchers aimed for an initial enrolment of 40 per group to allow for attrition; unfortunately, they were unable to achieve full sample size. The results did not indicate any difference between groups in terms of the primary outcome, symptomatic UTIs; however, the small sample size limits the conclusion, and it is therefore difficult to say with certainty that there is no difference between groups. The authors note that antibiotic prescriptions were higher in the non-hydrophilic catheter group, a finding that could be explored further.
Properly powered clinical intervention trials on continence management are challenging and often frustrating experiences for researchers. Although it is easy to criticise enrolment and follow-up in this and other studies, the reality is that clinical intervention studies are expensive, often have unexpected issues, frequently take longer to conduct than expected and often do not achieve required sample size. Indeed, the Cochrane Collaboration developed, in part, precisely to address this issue: when small trials which in themselves do not have statistically significant results are combined in a meta-analysis (provided outcome measures were similar), they provide guidance on the direction of evidence.
There are some points worth considering in the design and conduct of this study. The authors followed the recommended reporting format for a randomised controlled trial (Consort Statement) and used appropriate statistical tests. It is not clear whether the analysis accounted for dropouts (intention to treat). The authors note two limitations in addition to sample size: self-reported symptoms potentially leading to recall bias and the inclusion of few women. It is notable that there were more women in the control group (11, or 48%) than in the treatment group (5, or 23%), and being a woman was significantly associated with having a UTI. The authors do not report the gender of those experiencing UTIs during the study, but this gender imbalance between groups is a possible source of bias; that is, the lower number of women in the hydrophilic catheter group (rather than the type of catheter) may account for the lower number of UTIs.
Further points for consideration are the randomisation method and how blinding occurred in data analysis. Follow-up was monthly for only 3 months and then every 3 months, potentially missing symptoms or generating issues of recall. More frequent follow-up (at least monthly for the 12 months of the study) and direct contact with the research nurse when any symptoms of a presumed UTI occurred would have helped to improve data reliability. A further limitation is the absence of a completed participant opinion questionnaire on the two products; although cost is the typical impetus behind product choice, studies on continence products have shown varying opinions among users, and given a choice users would make wise decisions on the basis of both products and cost.3
This study on its own will not change practice. It does, however, add to the number of trials conducted on intermittent catheterisation and UTI, and it supports the limited current research that no trials on their own provide convincing evidence of product differences among single-use PVC, single-use hydrophilic and multiuse PVC catheters. A large multicentre trial is needed on this topic. This is particularly important because of cost differences between hydrophilic catheters and PVC catheters. A further question is whether reused PVC catheters place the patient at greater risk for UTIs. To date, there is insufficient evidence to state that the incidence of UTIs is higher in individuals who reuse their catheters.
It is unknown whether hydrophilic catheters are better than single-use PVC catheters (or reused catheters) in terms of control of UTIs, ease of use, individual acceptance or cost-effectiveness. Studies are needed that systematically explore the incidence of UTIs, prescription use, days missed from school or work, diagnostic testing, users' experiences with the different catheters, their opinions on reuse and their ability to adhere to a catheterisation protocol. Current practice is based on best opinion.
Competing interests None.