Abstract

Objective To determine whether antibiotic prophylaxis at the time of removal of a urinary catheter reduces the risk of subsequent symptomatic urinary tract infection.

Design Systematic review and meta-analysis of studies published before November 2012 identified through PubMed, Embase, Scopus, and the Cochrane Library; conference abstracts for 2006-12 were also reviewed.

Inclusion criteria Studies were included if they examined antibiotic prophylaxis administered to prevent symptomatic urinary tract infection after removal of a short term (≤14 days) urinary catheter.

Results Seven controlled studies had symptomatic urinary tract infection after catheter removal as an endpoint; six were randomized controlled trials (five published; one in abstract form) and one was a non-randomized controlled intervention study. Five of these seven studies were in surgical patients. Studies were heterogeneous in the type and duration of antimicrobial prophylaxis and the period of observation. Overall, antibiotic prophylaxis was associated with benefit to the patient, with an absolute reduction in risk of urinary tract infection of 5.8% between intervention and control groups. The risk ratio was 0.45 (95% confidence interval 0.28 to 0.72). The number needed to treat to prevent one urinary tract infection was 17 (12 to 30).

Conclusions Patients admitted to hospital who undergo short term urinary catheterization might benefit from antimicrobial prophylaxis when the catheter is removed as they experience fewer subsequent urinary tract infections. Potential disadvantages of more widespread antimicrobial prophylaxis (side effects and cost of antibiotics, development of antimicrobial resistance) might be mitigated by the identification of which patients are most likely to benefit from this approach.

Discussion

In our meta-analysis of pooled data from seven studies (six of which were randomized), there were significantly fewer symptomatic urinary tract infections in patients receiving prophylaxis during removal of a urinary catheter than in those not receiving prophylaxis. Our finding in favor of antibiotic prophylaxis, however, must be tempered by possible publication bias toward positive studies, the limitations of the included studies, and practical considerations about encouraging more widespread antibiotic use.

Indwelling urinary catheters pose several risks to patients, including urethral trauma, discomfort, and urinary tract infection.³¹ In an era of increasingly constrained fiscal resources and evolving antibiotic resistance, evidence based antimicrobial prescribing is essential to promote antimicrobial stewardship.³² Unfortunately, there is no consensus on whether clinicians should prescribe antibiotic prophylaxis to patients when an indwelling urinary catheter is removed.

Conclusions

This meta-analysis of available data indicates an overall benefit of antibiotic prophylaxis at the time of removal of a urinary catheter to prevent subsequent urinary tract infections. The number needed to treat indicates that 17 patients would need to receive prophylaxis to prevent one symptomatic urinary tract infection. We know little, however, about the potential negative consequences of implementing antibiotic prophylaxis in this setting in a wider frame or indeed which types of patients would be most likely to benefit. Increasing antimicrobial resistance, healthcare costs for antibiotics, and the potential for side effects of antibiotic administration are disadvantages that merit careful review. From a public health standpoint, we should be careful not to encourage antibiotic use when it might not be necessary. The healthcare provider of a catheterized patient, however, might consider antibiotic prophylaxis before catheter removal, after taking individual risk factors into account. Future studies should better characterize who is at risk of developing symptomatic urinary tract infection after catheter removal (whether bacteriuric or not) and then examine antibiotic prophylaxis in those at greatest risk.

What is already known on this topic

• Catheterization of the urinary tract is associated with an increased risk of bacteriuria and symptomatic urinary tract infection
• Antibiotic administration at the time of removal of a urinary catheter might effectively reduce urinary tract infections, but guidelines for catheter associated infections note insufficient evidence to support this practice
• Antibiotic prophylaxis at the time of urinary catheter removal in general surgery, prostatectomy, and medical patients effectively reduced the incidence of symptomatic urinary tract infections with a number needed to treat of 17
• The effect size of antibiotic prophylaxis in this meta-analysis was stable to sensitivity analyses with exclusion of non-randomized trials and two studies in non-surgical patients

What this study adds.

Source: BMJ

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�� �� -border-alt:none windowtext 0in; padding:0in’>12 ^1314 16 Although other studies have examined the links between acute kidney injury and mortality and end stage renal disease in people admitted to hospital with myocardial infarction treated with either invasive or medical management,^18 33 these studies have not compared renal outcomes on the basis of treatment strategies.

Our findings show that acute kidney injury is a relatively common complication in people with non-ST elevation acute coronary syndrome and chronic kidney disease and increases substantially with lower baseline estimated glomerular filtration rate. However, the difference in the incidence of acute kidney injury between people who receive early invasive management and similar patients treated conservatively is relatively small. Importantly, despite the modestly higher risk of acute kidney injury associated with early invasive management at all levels of estimated glomerular filtration rate, our findings suggest that this strategy is not associated with higher risks of more clinically relevant renal outcomes (including acute dialysis or progression to end stage renal disease), which occurred much less often at all levels of baseline estimated glomerular filtration rate, regardless of treatment strategy. Since early invasive management seemed to be consistently associated with a long term survival advantage at all levels of baseline estimated glomerular filtration rate, these findings (interpreted in light of their consistency with results from randomised trials showing that early invasive management improves long term survival in high risk patients^3 4) suggest that restricting or delaying access to invasive coronary procedures may not avoid most cases of clinically relevant acute kidney injury and could deny high risk individuals (including those with pre-existing chronic kidney disease) important benefits.

There are several potential mechanisms for the higher risk of acute kidney injury associated with early invasive management. People who received early invasive management were more likely to receive coronary angiography, percutaneous coronary intervention, coronary artery bypass grafting surgery, and angiotensin converting enzyme inhibitors or angiotensin receptor blockers, placing them at risk of acute kidney injury from contrast exposure, perioperative ischaemia, and haemodynamic effects. Furthermore, patients who received invasive management had a longer hospital stay and more measurements of creatinine during follow-up, which may have increased the probability that acute kidney injury would be ascertained. However, the magnitude of the increased risk associated with invasive management strategies was small, suggesting that patients’ characteristics such as age, comorbidity, pre-existing chronic kidney disease, drug use (including diuretics and inhibitors of the renin angiotensin system), and haemodynamic instability are more important contributors to the risk of acute kidney injury in patients with acute coronary syndrome than whether or not they are managed invasively or medically.

The better survival associated with early invasive management of non-ST elevation acute coronary syndrome in this cohort are in keeping with the clinical benefits of angiography and revascularisation reported in clinical trials, including subgroups with pre-existing chronic kidney disease.^2 3 4 Although episodes of acute kidney injury have been linked to an increased risk of end stage renal disease,^18 19 34 we did not observe a higher risk of end stage renal disease in people with otherwise similar characteristics who received early angiography despite the higher risk of acute kidney injury, even among strata with lower baseline estimated glomerular filtration rate. Radiocontrast associated acute kidney injury is typically manifested by a small change in serum creatinine levels, rarely leads to acute dialysis, and is usually reversible.¹⁰ Our findings suggest that the majority of such additional episodes of acute kidney injury associated with invasive procedures may confer relatively low risks of progression to end stage renal disease, although further studies are needed to help predict those at risk of progressive chronic kidney disease after acute kidney injury.

Conclusion

In conclusion, early invasive management of non-ST elevation acute coronary syndrome is associated with a small increase in the risk of acute kidney injury compared with a conservative management approach but is not associated with higher risks of in-hospital acute kidney injury requiring dialysis or long term risk of end stage renal disease. Given the improvement in cardiovascular outcomes and long term survival observed with early invasive management, these results suggest that invasive treatments should not be withheld solely because of concern they might increase the risk of kidney injury.

What is already known on this topic

• Acute kidney injury after invasive coronary procedures is associated with adverse outcomes, including end stage renal disease and death
• Fear of precipitating contrast induced acute kidney injury possibly contributes to underuse of invasive treatments for acute coronary syndrome in people at high risk of kidney disease
• Comparisons of renal outcomes between people treated with invasive versus conservative management are lacking
• People who received early invasive management for non-ST segment elevation acute coronary syndrome were modestly more likely to develop acute kidney injury
• After early invasive management the risks of requiring dialysis and long term risk of end stage renal disease were similar, and patients had better long term survival than those treated conservatively
• These findings were consistent across varying levels of baseline kidney function, suggesting similar relative risks and benefits of early invasive management in people with and without pre-existing kidney disease

What this study adds

Source: BMJ