Whether nitrofurazone-impregnated catheters have a clinically important impact on the risk of UTI compared to standard catheters is uncertain, but they may be cost-effective for the NHS
- Correspondence to
: Dr Jacqui Prieto
Faculty of Health Sciences, University of Southampton, Level A, South Academic Block (MP 11), Southampton General Hospital, Tremona Road, Southampton, Hampshire SO16 6YD, UK;
Implications for practice and research
This study provides evidence that antimicrobial urethral catheters may not benefit patients admitted to hospital for elective surgery and therefore standard catheters are recommended.
Further research is needed to determine whether antimicrobial urethral catheters would benefit patients hospitalised for medical or critical care reasons.
Around 25% of the hospitalised patients undergo short-term indwelling catheterisation,1 which accounts for up to 80% of healthcare-associated urinary tract infection (UTI).2 The incidence of bacteriuria (bacterial contamination of urine) among catheterised patients is approximately 5% per day1 and infection is estimated to develop in one quarter of patients with bacteriuria.1 The potential of antimicrobial catheters to reduce UTI has been unclear, as although it is known that they can reduce the rate of bacteriuria3 evidence for an associated reduction in morbidity related to symptomatic UTI has been lacking. Antimicrobial catheters are around five times more expensive than standard catheters, yet silver alloy-coated catheters in particular have been promoted for widespread use in the UK National Health Service, despite insufficient evidence of their cost-effectiveness.4
This is a well-designed multicentre randomised controlled trial which compares the incidence of symptomatic UTIs between hospitalised patients undergoing short-term urethral catheterisation with one of three catheter types: silver-alloy-coated latex; nitrofural-impregnated silicone; or standard polytetrafluoroethylene (PTFE)-coated latex. The study was powered sufficiently to detect a 3.3% absolute reduction in UTI, requiring a sample size of 2000 patients per group. Patients were recruited from 24 UK hospitals and although the aim was to recruit widely from surgical, medical and critical care units, it proved too resource-intensive to recruit patients undergoing unplanned catheterisation; so patients admitted for elective surgery who required planned catheterisation became the target population. Symptomatic catheter-associated urinary tract infection (CAUTI) was defined as patient-reported symptoms of UTI accompanied by a confirmed clinician prescription of an antibiotic for UTI, but without the requirement for microbiological confirmation of the diagnosis.
Full sample size was achieved and 6394 patients were included in the primary outcome analysis according to the intention to treat principles. There was no clinically significant difference in the incidence of symptomatic UTI between the intervention and control groups, which were comparable in relation to baseline characteristics, duration of catheter use and response rates to questionnaires. The vast majority (>95%) of patients underwent planned catheterisation as part of an elective intervention. The mean duration of catheterisation was 2–3 days. Economic analysis suggested the potential for nitrofural-impregnated catheters to be cost-effective, but this is uncertain.
This trial provides definitive evidence of the lack of effectiveness of antimicrobial catheters for reducing the risk of symptomatic UTI in hospitalised patients. The findings are particularly important regarding the lack of benefit of silver alloy-coated catheters given the extent to which they have been promoted for use.4 In relation to nitrofural-impregnated catheters, a lower rate of symptomatic UTI was found, but this did not reach the level of difference predetermined by the researchers to be clinically important. In view of this, there appears to be no compelling case to use nitrofural-impregnated catheters in place of standard catheters, particularly given the uncertainty about their cost-effectiveness and the risk that they may contribute towards antimicrobial resistance among urinary pathogens.
The study sample is generally representative of patients undergoing short-term catheterisation for planned surgery. However, while the specialties represented are listed per centre, the number of patients recruited per specialty is not reported. It is possible, therefore, that the representation of certain specialties, for example, obstetrics and gynaecology, is disproportionate within the study sample. Nonetheless, the findings are likely to be of equal relevance to all patients undergoing short-term catheterisation for planned surgery.
Owing to the problems with recruitment experienced by the researchers, it is difficult to ascertain whether the study findings are applicable to patients hospitalised for medical or critical care reasons. Indeed, these patients are generally more seriously unwell than patients undergoing elective surgery, are often hospitalised much longer and are catheterised for a longer duration. In view of this, it is unclear whether they would benefit from use of antimicrobial catheters. However, until more evidence is available, there is no clear reason to use antimicrobial catheters in place of standard catheters.