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Original Investigation |

The Potential Clinical and Economic Benefits of Silver Alloy Urinary Catheters in Preventing Urinary Tract Infection FREE

Sanjay Saint, MD, MPH; David L. Veenstra, PharmD, PhD; Sean D. Sullivan, PhD; Carol Chenoweth, MD; A. Mark Fendrick, MD
[+] Author Affiliations

From the Divisions of General Medicine (Drs Saint and Fendrick) and Infectious Diseases (Dr Chenoweth), Department of Internal Medicine, The University of Michigan Health System, Ann Arbor; and the Department of Pharmacy, University of Washington, Seattle (Drs Veenstra and Sullivan). None of the authors has received financial support from or holds any personal financial interest in the manufacturer of silver alloy urinary catheters.


Arch Intern Med. 2000;160(17):2670-2675. doi:10.1001/archinte.160.17.2670.
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Published online

Background  Catheter-associated urinary tract infection (UTI) is associated with increased morbidity, mortality, and costs. A recent meta-analysis concluded that silver alloy catheters reduce the incidence of UTI by 3-fold; however, clinicians must decide whether the efficacy of such catheters is worth the extra per unit cost of $5.30.

Objective  To assess the clinical and economic impact of using silver alloy urinary catheters in hospitalized patients.

Methods  The decision model, performed from the health care payer's perspective, evaluated a simulated cohort of 1000 hospitalized patients on general medical, surgical, urologic, and intensive care services requiring short-term urethral catheterization (2-10 days). We compared 2 catheterization strategies: silver alloy catheters and standard (noncoated) urinary catheters. Outcomes included the incidence of symptomatic UTI and bacteremia and direct medical costs.

Results  In the base-case analysis, use of silver-coated catheters led to a 47% relative decrease in the incidence of symptomatic UTI from 30 to 16 cases per 1000 patients (number needed to treat = 74) and a 44% relative decrease in the incidence of bacteremia from 4.5 to 2.5 cases per 1000 patients (number needed to treat = 500) compared with standard catheters. Use of silver alloy catheters resulted in estimated cost savings of $4.09 per patient compared with standard catheter use ($20.87 vs $16.78). In a multivariate sensitivity analysis using Monte Carlo simulation, silver-coated catheters provided clinical benefits over standard catheters in all cases and cost savings in 84% of cases.

Conclusions  Using silver alloy catheters in hospitalized patients requiring short-term urinary catheterization reduces the incidence of symptomatic UTI and bacteremia, and is likely to produce cost savings compared with standard catheters.

Figures in this Article

WORLDWIDE, 96 million indwelling urethral catheters are sold annually; 24 million of these are sold in the United States. Approximately 25% of hospitalized patients have a urinary catheter placed at some time during their stay.1 The incidence of bacteriuria in catheterized patients is approximately 5% per day.1 Symptomatic urinary tract infection (UTI) occurs in approximately 20% of those with bacteriuria,2,3 with bacteremia complicating bacteriuria in up to 4% of patients.4,5

Given the morbidity and costs associated with catheter-related UTI,6 preventive measures have been attempted, including the addition of silver coating to urinary catheters. A recent meta-analysis7 concluded that silver alloy catheters significantly reduced bacteriuria by 3-fold compared with standard, noncoated catheters. Clinicians must decide whether the improved efficacy of silver alloy urinary catheters is worth the extra per unit cost of approximately $5. To assist decision makers in evaluating these catheters, we used decision-analytic techniques to assess the incremental clinical and economic impact of using urinary catheters coated with silver alloy in hospitalized patients requiring catheterization.

DECISION MODEL

We compared 2 catheterization strategies: silver alloy catheters and standard, noncoated, urinary catheters (Figure 1). The hypothetical cohort in the decision-analytic model consisted of patients admitted to hospitals on general medical, surgical, urologic, and intensive care services requiring the short-term use (2-10 days) of indwelling urethral catheterization. We chose this cohort because most patients in the clinical trials evaluating the effectiveness of silver-coated catheters included these populations, and these patients are the primary recipients of indwelling catheters in clinical practice. A catheter duration of 2 to 10 days was chosen because most of the trials excluded catheters in place for less than 1 day and the average duration of catheterization in the trials was approximately 7 days (range, 3-21 days). The analysis was performed from the perspective of the health care payer, and the time horizon was defined as the period of hospitalization. Decision-analytic software (DATA 3.5; Treeage, Williamstown, Mass) was used for all analyses.

Place holder to copy figure label and caption

Decision model. Patients requiring urethral catheterization for 2 to 10 days will be given either silver-coated urinary catheters or standard catheters. The square represents the choice between these 2 strategies; circles, chance outcomes. UTI indicates urinary tract infection.

Graphic Jump Location
LIKELIHOOD OF CLINICAL EVENTS

The probabilities and ranges of clinical events used in the decision model are shown in Table 1. The baseline risk of bacteriuria over the hospital stay in the control group (patients not receiving systemic antimicrobial agents and given short-term standard noncoated catheters) was statistically pooled from several prospective studies.817 The probability of developing a symptomatic UTI and bacteremia once bacteriuria developed was derived from the published literature.25,18,19 We assumed that the remaining 72% of patients with asymptomatic bacteriuria did not experience any adverse clinical sequelae or incur costs.

Table Graphic Jump LocationTable 1. Outcome and Cost Estimates Used in the Decision Tree*
PROTECTIVE EFFECT OF SYSTEMIC ANTIMICROBIAL AGENTS AND SILVER CATHETERS

The probability of developing bacteriuria was dependent on the concomitant use of systemic antimicrobial agents and the catheter type. Approximately 80% of hospitalized patients receive antibiotics and are thus at lower risk for UTI.12,20,21 The relative risk reduction of bacteriuria (or protective effect) associated with antimicrobial use of 65% was derived from 5 studies2,9,11,13,20 that adjusted for several factors (eg, sex and duration of catheterization) that affect the likelihood of developing bacteriuria. Similarly, the 45% relative risk reduction (or protective effect) associated with silver catheter use came from a meta-analysis of 5 randomized controlled trials. The probability of bacteriuria in patients with silver catheters who were not receiving systemic antimicrobial agents was a function of the relative risk reduction of silver catheters and the baseline probability of bacteriuria in the control group. The probability of developing bacteriuria for those taking systemic antibiotics was calculated in an analogous manner.

COSTS

The cost estimates used in the model are shown in Table 1. The additional cost of a silver alloy catheter compared with a standard catheter is $5.30 (Marjory Greenhalgh, BA, at C. R. Bard, Inc, Covington, Ga, oral communication, July 2000). Urinalysis, urine culture, and blood culture costs were derived by converting the Current Procedural Terminology–based charges attributed to each of these tests to costs via The University of Michigan Health System's Medicare cost-charge ratio of 0.57. Hospital room costs were derived by multiplying the number of excess hospital days by per diem room costs after estimating the increased hospital days attributed to symptomatic UTI and bacteremia from literature reports.2224 Antimicrobial costs were derived from The University of Michigan Health System pharmacy, Ann Arbor. Costs in 1998 US dollars are reported.

The estimated cost of a symptomatic UTI included the cost of urinalysis, urine culture and sensitivity, 7 days of therapy with a combination of oral trimethoprim and sulfamethoxazole, and one half extra day on the hospital ward. For patients with symptomatic UTI receiving systemic antimicrobial agents, oral norfloxacin was used rather than trimethoprim-sulfamethoxazole since these patients potentially could have acquired an organism resistant to trimethoprim-sulfamethoxazole. The added cost per case of symptomatic UTI for those not already taking systemic antimicrobial agents was $374; for those already taking systemic antimicrobial agents, it was $402. The estimated cost of bacteremia included the cost of urinalysis, urine culture and sensitivity, 2 sets of blood cultures, 3 days of intravenous ampicillin and gentamicin sulfate treatment, 11 days of oral trimethoprim-sulfamethoxazole therapy, and 3 extra days on the hospital ward. Thus, the estimate used in the base-case analysis for the incremental cost of bacteremia was $2041.

OUTCOME ASSESSMENT AND SENSITIVITY ANALYSES

The outcomes estimated using the decision-analytic model for 1000 hospitalized patients requiring short-term catheterization were the incidence of symptomatic UTI and bacteremia and direct medical costs. To determine the effects of specific inputs on the results, we performed a series of 1-way sensitivity analyses using the ranges in Table 1. Notably, the low estimate for the incidence of symptomatic UTI was 8% and that for the incidence of bacteremia was 0%. In addition, the low end of our cost estimates included no extra days of hospitalization due to symptomatic UTI and only one extra ward day due to bacteremia.

To evaluate the impact of the uncertainty in all of the variables simultaneously, we performed a multivariate sensitivity analysis using Monte Carlo simulation.25 Such a calculation provides an estimate of overall uncertainty by simulating the use of 10,000 catheters, where the clinical probabilities and costs are randomly drawn from probability distributions that represent the uncertainty of each of the variables.

CLINICAL AND ECONOMIC OUTCOMES

In the base-case analysis, use of silver-coated catheters led to a 47% relative decrease in the incidence of symptomatic UTI from 30 to 16 cases per 1000 patients (number needed to treat = 74) and a 44% relative decrease in the incidence of bacteremia from 4.5 to 2.5 cases per 1000 patients (number needed to treat = 500) compared with standard catheters. In addition to these clinical advantages, use of silver-coated catheters resulted in an estimated cost savings of $4.09 per patient compared with standard catheter use ($20.87 vs $16.78).

SENSITIVITY AND THRESHOLD ANALYSES

The 1-way sensitivity analyses revealed that the silver-coated catheter strategy remained dominant throughout the ranges evaluated in Table 1. We determined threshold values for the following variables since they were particularly influential in the 1-way sensitivity analyses: baseline incidence of bacteriuria in the control group, probability of developing symptomatic UTI after bacteriuria, efficacy of silver-coated catheters, and cost of a silver-coated catheter. The probability of developing bacteriuria in patients receiving short-term catheterization with standard catheters and not receiving systemic antimicrobial agents would have to be less than 15% for the silver-coated catheters to not be cost saving. Similarly, the probability of symptomatic UTI (without bacteremia) after developing bacteriuria would have to be less than 5% for the silver-coated catheters to no longer provide cost savings. At a relative risk reduction associated with silver-coated catheters of 25% or greater (relative risk, ≤0.75), the clinical and economic superiority of the silver-coated catheter strategy persists. Finally, the cost of a silver-coated catheter would have to average $9.40 more than a standard catheter for silver-coated catheters to not be cost saving. Threshold estimates for all pertinent variables are outlined in Table 2.

Table Graphic Jump LocationTable 2. Threshold Values for Several Individual Variables Used in the Decision-Analysis Model*

The 95% central range of values obtained from the Monte Carlo simulation for silver-coated vs standard catheters revealed a reduced incidence of symptomatic UTI (5-31 cases per 1000 catheterized patients), a reduced incidence of bacteremia (0.8-4.5 cases per 1000 catheterized patients), and a cost difference ranging from a savings of $17.22 to an increase in overall cost of $3.19 per catheterized patient. In the simulation, silver-coated catheters provided clinical benefits over standard catheters in all patients and cost savings in 84% of patients.

Since up to 80% of patients with a nosocomial UTI have an indwelling urinary catheter,5 the best prevention strategy would be to avoid catheterization. However, indwelling urinary catheters are often necessary in hospitalized patients. Because of the high incidence and substantial morbidity associated with nosocomial UTI, silver-coated catheters have been developed to prevent catheter-related UTI in those requiring catheterization. The results estimated by our decision model indicate that using silver-coated catheters for patients requiring short-term urinary catheterization reduces the incidence of symptomatic UTI and bacteremia, and is likely to produce cost savings compared with standard catheters. This combination of clinical benefit and likely decreased costs makes silver alloy urinary catheters attractive for routine use in certain hospitalized patient populations requiring short-term catheterization.

The uncertainty of several of the variables used in our analysis merits discussion. The estimate of symptomatic UTI without bacteremia was based on the only 2 relevant prospective studies we could locate; the point estimates from these studies were 12%2 and 32%.3 We further broadened the range of estimates used in the sensitivity analyses to include an even lower incidence of symptomatic UTI than reported in the literature. The threshold value for incidence of symptomatic UTI was less than half of the lower of these 2 estimates. Similarly, the attributable costs of symptomatic UTI and bacteremia in this patient population are not clear. We thus used a broad range for our sensitivity analyses, including rather low estimates for each. Encouragingly, our threshold analyses indicated that the cost of an episode of symptomatic UTI or bacteremia would have to be a fraction of the base-case estimates for each ($87 and $17, respectively) for the silver-coated catheter strategy to no longer provide cost savings. In addition, we were conservative by not including the extra costs associated with physician or nursing time and routine blood tests (complete blood cell count or chemistry panels) and by only including the minimum number of laboratory tests and antimicrobial regimens required to diagnose and treat symptomatic UTI or bacteremia in a patient. Finally, we used charges to derive costs, which are admittedly only estimates of the actual opportunity costs. We are reassured that the range of costs we used for a day on the inpatient ward, for example, includes the daily cost of an inpatient day at other academic medical centers, including the University of California at San Francisco Medical Center ($550) (S. Flanders, MD, written communication, February 11, 2000) and the University of Washington Medical Center, Seattle ($375).26

The efficacy of silver-coated catheters was based on the results of 5 randomized trials, only one of which was performed in the United States and was published in abstract form.21 In a recently published meta-analysis,7 we found that silver alloy catheters were effective in reducing bacteriuria while silver oxide catheters were not. We statistically pooled the results of the most recent trial21 evaluating silver alloy catheters with the results of the 4 previous silver alloy trials1417 included in the meta-analysis. It was previously demonstrated that estimates of effectiveness derived from meta-analysis are usually appropriate for use within cost-effectiveness analyses.27 Encouragingly, 2 separate before-and-after studies recently performed in the United States found that the reduction in catheter-related UTI (40%28 and 55%29) is similar to the 45% risk reduction we estimated.

All of the trials included in our analysis used bacteriuria as an outcome measure rather than symptomatic UTI or bacteremia. Studies evaluating these latter outcomes would be helpful in more precisely determining the ultimate clinical benefit of silver catheters, but will require many patients. In fact, we believe that ideally a large, multicenter trial randomizing patients to either silver alloy or standard noncoated catheters be performed to confirm our findings. Such a clinical trial should have a formal economic analysis conducted alongside, and should be adequately powered to detect a clinically significant decrease in symptomatic UTI, not just bacteriuria. Such a trial would require 1939 patients in each arm to have 80% power to detect the reduction in symptomatic UTI incidence that we have estimated. Similarly, 14,669 patients in each arm would be required if catheter-related bacteremia becomes the primary outcome of interest. Given the sample size estimates, however, such a study would be expensive and time-consuming. A benefit of decision analysis is to provide estimates of clinical effectiveness by modeling clinical outcomes using established surrogate measures, such as bacteriuria. Thus, until the data outlined become available, our results suggest that silver-coated urinary catheters are likely to provide clinical benefits and cost savings for hospitalized patients requiring short-term catheterization over a reasonable range of cost and effectiveness variables.

The results of our study are not generalizable to all patients requiring indwelling catheters. The use of silver-coated catheters in those requiring less than 2 days of catheterization (eg, peripartum or some postoperative patients) and in those requiring long-term catheterization (eg, patients with injured spinal cords) may not lead to cost savings. Furthermore, it is unlikely that physicians will be able to determine at the time of hospital admission which patients are likely to be catheterized between 2 and 10 days. Thus, to most effectively use this new catheter, health care systems should estimate the average duration of catheterization for patients admitted to the different hospital wards, providing either silver-coated or standard catheters. This type of evaluation at the University of Michigan Medical Center revealed that most indwelling catheters were used between 2 and 10 days in all catheterized adult patient groups except those in the obstetric wards and patients undergoing some surgical procedures. Thus, one potential strategy would be to stock silver-coated catheters throughout the hospital except on the obstetric floor and in the operating room. Further studies are needed, however, to more clearly identify patient groups likely to derive the greatest amount of benefit from these catheters.

Until definitive evidence about the clinical and economic consequences of silver alloy catheters vs standard catheters becomes available, decision makers must decide whether to begin the routine use of these new catheters in their hospitals. Our decision-analytic model suggests that silver alloy catheters are likely to produce clinical and economic benefit, an unusual and attractive combination. Several well-studied methods of preventing catheter-related UTI have been previously proved to be useless, including irrigation of the bladder, instilling antimicrobial agents in the drainage bag, and rigorously cleaning the meatus.30 Given the difficulties in preventing catheter-related UTI and the potential clinical and economic benefit associated with silver alloy catheters, this relatively simple intervention should be strongly considered in the appropriate clinical settings.

Accepted for publication March 8, 2000.

This study was supported in part through a grant from the Association of Practitioners of Infection Control Research Foundation, Washington, DC; a postdoctoral fellowship from Roche, Palo Alto, Calif (Dr Veenstra); and grants HS/HL08368-01A1 and HS07834-03S1 from the National Institutes of Health, Bethesda, Md (Dr Sullivan). Dr Saint was a Robert Wood Johnson Clinical Scholar at the time much of this work was conducted.

Presented in part at the 17th Annual VA Health Services Research & Development National Meeting, Washington, DC, February 24-26, 1999; and at the 22nd Annual Society of General Internal Medicine National Meeting, San Francisco, Calif, April 29-May 1, 1999.

Corresponding author: Sanjay Saint, MD, MPH, Division of General Medicine, Department of Internal Medicine, University of Michigan, 3116 Taubman Center, Campus Box 0376, Ann Arbor, MI 48109-0376 (e-mail: saint@umich.edu).

Haley  RWHooton  TMCulver  DH  et al.  Nosocomial infections in US hospitals, 1975-1976: estimated frequency by selected characteristics of patients. Am J Med. 1981;70947- 959
Hartstein  AIGarber  SBWard  TTJones  SRMorthland  VH Nosocomial urinary tract infection: a prospective evaluation of 108 catheterized patients. Infect Control. 1981;2380- 386
Garibaldi  RAMooney  BREpstein  BJBritt  MR An evaluation of daily bacteriologic monitoring to identify preventable episodes of catheter-associated urinary tract infection. Infect Control. 1982;3466- 470
Bryan  CSReynolds  KL Hospital-acquired bacteremic urinary tract infection: epidemiology and outcome. J Urol. 1984;132494- 498
Krieger  JNKaiser  DLWenzel  RP Urinary tract etiology of bloodstream infections in hospitalized patients. J Infect Dis. 1983;14857- 62
Saint  S Clinical and economic consequences of nosocomial catheter-related bacteriuria. Am J Infect Control. 2000;2868- 75
Saint  SElmore  JGSullivan  SDEmerson  SSKoepsell  TD The efficacy of silver alloy–coated urinary catheters in preventing urinary tract infection: a meta-analysis. Am J Med. 1998;105236- 241
Huth  TSBurke  JPLarsen  RAClassen  DCStevens  LE Randomized trial of meatal care with silver sulfadiazine cream for the prevention of catheter-associated bacteriuria. J Infect Dis. 1992;16514- 18
Huth  TSBurke  JPLarsen  RAClassen  DCStevens  LE Clinical trial of junction seals for the prevention of urinary catheter–associated bacteriuria. Arch Intern Med. 1992;152807- 812
Platt  RPolk  BFMurdock  BRosner  B Reduction of mortality associated with nosocomial urinary tract infection. Lancet. 1983;1893- 897
Platt  RPolk  BFMurdock  BRosner  B Risk factors for nosocomial urinary tract infection. Am J Epidemiol. 1986;124977- 985
Riley  DKClassen  DCStevens  LEBurke  JP A large randomized clinical trial of a silver-impregnated urinary catheter: lack of efficacy and staphylococcal superinfection. Am J Med. 1995;98349- 356
Shapiro  MSimchen  EIzraeli  SSacks  TG A multivariate analysis of risk factors for acquiring bacteriuria in patients with indwelling urinary catheters for longer than 24 hours. Infect Control. 1984;5525- 532
Liedberg  HLundeberg  T Silver alloy coated catheters reduce catheter-associated bacteriuria. Br J Urol. 1990;65379- 381
Liedberg  HLundeberg  T Prospective study of incidence of urinary tract infection in patients catheterized with bard hydrogel and silver-coated catheters or bard hydrogel–coated catheters [abstract]. J Urol. 1993;149405A
Liedberg  HLundeberg  TEkman  P Refinements in the coating of urethral catheters reduces the incidence of catheter-associated bacteriuria: an experimental and clinical study. Eur Urol. 1990;17236- 240
Lundeberg  T Prevention of catheter-associated urinary-tract infections by use of silver-impregnated catheters [letter]. Lancet. 1986;21031
Emori  TGBanerjee  SNCulver  DH  et al.  Nosocomial infections in elderly patients in the United States, 1986-1990: National Nosocomial Infections Surveillance System. Am J Med. 1991;91(suppl 3B)289S- 293S
Horan  TCCulver  DHGaynes  RPJarvis  WREdwards  JRReid  CR Nosocomial infections in surgical patients in the United States, January 1986–June 1992: National Nosocomial Infections Surveillance (NNIS) System. Infect Control Hosp Epidemiol. 1993;1473- 80
Johnson  JRRoberts  PLOlsen  RJMoyer  KAStamm  WE Prevention of catheter-associated urinary tract infection with a silver oxide–coated urinary catheter: clinical and microbiologic correlates. J Infect Dis. 1990;1621145- 1150
Maki  DGKnasinski  VHalvorson  KTambyah  PA A novel silver-hydrogel–impregnated indwelling urinary catheter reduces catheter-related urinary tract infections: a prospective double-blind trial [abstract]. Infect Control Hosp Epidemiol. 1998;19682Abstract 10.
Not Available, Public health focus: surveillance, prevention, and control of nosocomial infections. MMWR Morb Mortal Wkly Rep. 1992;41783- 787
Givens  CDWenzel  RP Catheter-associated urinary tract infections in surgical patients: a controlled study on the excess morbidity and costs. J Urol. 1980;124646- 648
Haley  RWSchaberg  DRCrossley  KBVon Allmen  SDMcGowan  JE  Jr Extra charges and prolongation of stay attributable to nosocomial infections: a prospective interhospital comparison. Am J Med. 1981;7051- 58
Doubilet  PBegg  CBWeinstein  MCBraun  PMcNeil  BJ Probabilistic sensitivity analysis using Monte Carlo simulation: a practical approach. Med Decis Making. 1985;5157- 177
Veenstra  DLSaint  SSullivan  SD Cost-effectiveness of antiseptic-impregnated central venous catheters for the prevention of catheter-related bloodstream infection. JAMA. 1999;282554- 560
Saint  SVeenstra  DLSullivan  SD The use of meta-analysis in cost-effectiveness analysis: issues and recommendations. Pharmacoeconomics. 1999;151- 8
Bologna  RATu  LMPolansky  MFraimow  HDGordon  DAWhitmore  KE Hydrogel/silver ion–coated urinary catheter reduces nosocomial urinary tract infection rates in intensive care unit patients: a multicenter study. Urology. 1999;54982- 987
Lettau  LABlackhurst  DW Silver hydrogel–coated urinary catheters for the prevention of nosocomial urinary tract infection: a collaborative study in 9 community hospitals [abstract]. Clin Infect Dis. 1998;271020
Saint  SLipsky  BA Preventing catheter-related bacteriuria: can we? should we? how? Arch Intern Med. 1999;159800- 808

Figures

Place holder to copy figure label and caption

Decision model. Patients requiring urethral catheterization for 2 to 10 days will be given either silver-coated urinary catheters or standard catheters. The square represents the choice between these 2 strategies; circles, chance outcomes. UTI indicates urinary tract infection.

Graphic Jump Location

Tables

Table Graphic Jump LocationTable 1. Outcome and Cost Estimates Used in the Decision Tree*
Table Graphic Jump LocationTable 2. Threshold Values for Several Individual Variables Used in the Decision-Analysis Model*

References

Haley  RWHooton  TMCulver  DH  et al.  Nosocomial infections in US hospitals, 1975-1976: estimated frequency by selected characteristics of patients. Am J Med. 1981;70947- 959
Hartstein  AIGarber  SBWard  TTJones  SRMorthland  VH Nosocomial urinary tract infection: a prospective evaluation of 108 catheterized patients. Infect Control. 1981;2380- 386
Garibaldi  RAMooney  BREpstein  BJBritt  MR An evaluation of daily bacteriologic monitoring to identify preventable episodes of catheter-associated urinary tract infection. Infect Control. 1982;3466- 470
Bryan  CSReynolds  KL Hospital-acquired bacteremic urinary tract infection: epidemiology and outcome. J Urol. 1984;132494- 498
Krieger  JNKaiser  DLWenzel  RP Urinary tract etiology of bloodstream infections in hospitalized patients. J Infect Dis. 1983;14857- 62
Saint  S Clinical and economic consequences of nosocomial catheter-related bacteriuria. Am J Infect Control. 2000;2868- 75
Saint  SElmore  JGSullivan  SDEmerson  SSKoepsell  TD The efficacy of silver alloy–coated urinary catheters in preventing urinary tract infection: a meta-analysis. Am J Med. 1998;105236- 241
Huth  TSBurke  JPLarsen  RAClassen  DCStevens  LE Randomized trial of meatal care with silver sulfadiazine cream for the prevention of catheter-associated bacteriuria. J Infect Dis. 1992;16514- 18
Huth  TSBurke  JPLarsen  RAClassen  DCStevens  LE Clinical trial of junction seals for the prevention of urinary catheter–associated bacteriuria. Arch Intern Med. 1992;152807- 812
Platt  RPolk  BFMurdock  BRosner  B Reduction of mortality associated with nosocomial urinary tract infection. Lancet. 1983;1893- 897
Platt  RPolk  BFMurdock  BRosner  B Risk factors for nosocomial urinary tract infection. Am J Epidemiol. 1986;124977- 985
Riley  DKClassen  DCStevens  LEBurke  JP A large randomized clinical trial of a silver-impregnated urinary catheter: lack of efficacy and staphylococcal superinfection. Am J Med. 1995;98349- 356
Shapiro  MSimchen  EIzraeli  SSacks  TG A multivariate analysis of risk factors for acquiring bacteriuria in patients with indwelling urinary catheters for longer than 24 hours. Infect Control. 1984;5525- 532
Liedberg  HLundeberg  T Silver alloy coated catheters reduce catheter-associated bacteriuria. Br J Urol. 1990;65379- 381
Liedberg  HLundeberg  T Prospective study of incidence of urinary tract infection in patients catheterized with bard hydrogel and silver-coated catheters or bard hydrogel–coated catheters [abstract]. J Urol. 1993;149405A
Liedberg  HLundeberg  TEkman  P Refinements in the coating of urethral catheters reduces the incidence of catheter-associated bacteriuria: an experimental and clinical study. Eur Urol. 1990;17236- 240
Lundeberg  T Prevention of catheter-associated urinary-tract infections by use of silver-impregnated catheters [letter]. Lancet. 1986;21031
Emori  TGBanerjee  SNCulver  DH  et al.  Nosocomial infections in elderly patients in the United States, 1986-1990: National Nosocomial Infections Surveillance System. Am J Med. 1991;91(suppl 3B)289S- 293S
Horan  TCCulver  DHGaynes  RPJarvis  WREdwards  JRReid  CR Nosocomial infections in surgical patients in the United States, January 1986–June 1992: National Nosocomial Infections Surveillance (NNIS) System. Infect Control Hosp Epidemiol. 1993;1473- 80
Johnson  JRRoberts  PLOlsen  RJMoyer  KAStamm  WE Prevention of catheter-associated urinary tract infection with a silver oxide–coated urinary catheter: clinical and microbiologic correlates. J Infect Dis. 1990;1621145- 1150
Maki  DGKnasinski  VHalvorson  KTambyah  PA A novel silver-hydrogel–impregnated indwelling urinary catheter reduces catheter-related urinary tract infections: a prospective double-blind trial [abstract]. Infect Control Hosp Epidemiol. 1998;19682Abstract 10.
Not Available, Public health focus: surveillance, prevention, and control of nosocomial infections. MMWR Morb Mortal Wkly Rep. 1992;41783- 787
Givens  CDWenzel  RP Catheter-associated urinary tract infections in surgical patients: a controlled study on the excess morbidity and costs. J Urol. 1980;124646- 648
Haley  RWSchaberg  DRCrossley  KBVon Allmen  SDMcGowan  JE  Jr Extra charges and prolongation of stay attributable to nosocomial infections: a prospective interhospital comparison. Am J Med. 1981;7051- 58
Doubilet  PBegg  CBWeinstein  MCBraun  PMcNeil  BJ Probabilistic sensitivity analysis using Monte Carlo simulation: a practical approach. Med Decis Making. 1985;5157- 177
Veenstra  DLSaint  SSullivan  SD Cost-effectiveness of antiseptic-impregnated central venous catheters for the prevention of catheter-related bloodstream infection. JAMA. 1999;282554- 560
Saint  SVeenstra  DLSullivan  SD The use of meta-analysis in cost-effectiveness analysis: issues and recommendations. Pharmacoeconomics. 1999;151- 8
Bologna  RATu  LMPolansky  MFraimow  HDGordon  DAWhitmore  KE Hydrogel/silver ion–coated urinary catheter reduces nosocomial urinary tract infection rates in intensive care unit patients: a multicenter study. Urology. 1999;54982- 987
Lettau  LABlackhurst  DW Silver hydrogel–coated urinary catheters for the prevention of nosocomial urinary tract infection: a collaborative study in 9 community hospitals [abstract]. Clin Infect Dis. 1998;271020
Saint  SLipsky  BA Preventing catheter-related bacteriuria: can we? should we? how? Arch Intern Med. 1999;159800- 808

Correspondence

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Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).
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