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Use of silver-hydrogel urinary catheters on the incidence of catheter-associated urinary tract infections in hospitalized patients
Use of silver-hydrogel urinary catheters on the incidence of catheter-associated urinary tract infections in hospitalized patients Kwan Kew Lai, DMD, MDa Sally A. Fontecchio, RN, BSN, CICb Worcester and Boston, Massachusetts Background: Urinary tract infections (UTIs) account for 40% of all nosocomial infections, and about 80% of these are associated with the use of urinary catheters. They not only contribute to excess morbidity and mortality, but they also significantly add to the cost of hospitalization. Clinical trials with silver-coated urinary catheters have shown conflicting results. However, recent trials with silver-hydrogel urinary catheters have shown a reduction in nosocomial UTIs, and these catheters appear to offer cost savings. Method: The University of Massachusetts Medical Center is a teaching, tertiary hospital with 18% of its beds in intensive care units. The silver-hydrogel urinary catheters were introduced in October 1997. The rate of catheter-associated UTIs with silver-hydrogel urinary catheter use was compared with a historical baseline UTI rate that was established for January 1996 and January 1997 with the standard, noncoated catheters. The cost of a nosocomial catheter-associated UTI was estimated by calculating the hospital charges resulting from all urinary catheter-associated UTIs in 1 month. A cost-analysis of silver-hydrogel urinary catheter use was performed. Results: The rate of catheter-associated UTIs for noncoated catheters was 4.9/1000 patient-days compared with 2.7/1000 patientdays for the silver-hydrogel catheters, a reduction of 45% (P = .1). The average cost (calculated with hospital charges) of a catheterassociated UTI at our institution was estimated to be $1214.42, with a median of $613.72. The estimated cost-saving ranged from $12,563.52 to $142,314.72. Conclusions: The use of silver-hydrogel urinary catheters resulted in a nonsignificant reduction in catheter-associated UTIs and a modest cost-saving. (Am J Infect Control 2002;30:221-5.)
Urinary tract infections (UTIs) account for 40% of all nosocomial infections, and about 80% of these are associated with the use of urinary catheters.1,2 One out of every 4 hospitalized patients receive an indwelling urinary catheter, and the incidence of nosocomial UTIs is approximately 5% per day, with associated bacteremia in 4% of patients.2-4 Excess duration of hospital stay due to nosocomial UTIs has From the University of Massachusetts Medical School and UMass Memorial Medical Center,a Worcester, and Brigham and Women’s Hospital,b Boston. Presented in part at the 37th Annual Meeting of the Infectious Disease Society of America, Philadelphia, Pennsylvania, November 18-21, 1999. Reprint requests: Kwan Kew Lai, DMD, MD, UMass Memorial Medical Center, 55 Lake Avenue North, Worcester, MA 01655. Copyright © 2002 by the Association for Professionals in Infection Control and Epidemiology, Inc. 0196-6553/2002/$35.00 + 0 17/46/120128 doi:10.1067/mic.2002.120128
been estimated to be 1 to 4 additional days, and the estimated average cost of a nosocomial UTI on a nonICU floor is between $680 to $3803 per infection.2,4,5 When adjusted for inflation from 1992 to 1997 with use of the Consumer Price Index for medical care, the estimated cost in 1997 was $839.18 to $4693.23. Therefore, nosocomial UTIs not only contribute to excess morbidity and mortality, but they also significantly add to the cost of hospitalization. Several clinical trials with silver-coated urinary catheters have shown conflicting results. For example, small clinical trials that used silver-oxide–coated urinary catheters resulted in the reduction of the incidence of bacteriuria in selected patients.6-9 Liedberg and colleagues10 found that a silver-alloy and hydrogel-coated urinary catheter significantly reduced bacteriuria after 5 days of catheterization when compared with the noncoated catheters. However, Riley et al11 performed a large randomized clinical trial with silver-impregnated urinary catheters that failed to show prevention of bacteriuria but 221
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222 Vol. 30 No. 4
Table 1. Rates of nosocomial catheter-associated UTIs with uncoated urinary catheters during the baseline period and the silver-hydrogel urinary catheters during the baseline and evaluation periods Period Baseline (noncoated catheter) Average Evaluation (silver-hydrogel catheter)
Month/Year
No. CAUTIs
Patient-days*
CAUTI Rate/1000 patient-days
48 37 43 23 26 35 21 22 25
8571 8740 8656 8685 9234 9962 8961 8702 9109
5.6 4.2 4.9 2.6 2.8 3.5 2.3 2.5 2.7
1/96 1/97 11/97 1/98 3/98 7/98 8/98
Average CAUTI, Catheter-associated urinary tract infection. *Patient-days = patient-days for entire hospitalized patients.
found a significantly increased incidence of bacteriuria in male patients and a significantly increased incidence of staphylococcal bacteriuria. More recently, Karchmer et al,3 in a randomized, crossover study, reported a reduction in the risk for UTI infection by 21% among study wards in which patients resided randomized to silver-coated catheters and a 32% reduction among patients in whom the catheters were used on the wards. The catheters appeared to offer cost-savings. Given the costs associated with catheter-associated UTIs, decision was made to use silver-coated urinary catheters at the University of Massachusetts Medical Center. These silver-hydrogel catheters provide a hydrophilic coating that inhibits microbial adherence to the catheter surface and migration of bacteria intraluminally and extraluminally.10 Their use began October 1, 1997, and the rates of catheter-associated UTIs after that time were compared with the baseline historical rates associated with uncoated catheters that were collected in January 1996 and January 1997. We performed a cost-benefit analysis to see whether it was cost-effective to use these catheters.
was performed during the evaluation periods in November 1997 and January, March, July, and August 1998 with use of Centers for Disease Control and Prevention-defined criteria for UTIs. The medical records of patients with urine cultures positive for a UTI and urinalyses were reviewed. Patient-days were used to determine nosocomial UTI rates. To estimate the cost of a catheter-associated UTI, all patients with UTI associated with catheters in the month of January 1997 were studied. Because these patients came from all over the hospital, they represented the general population of hospitalized patients. Medical records were reviewed closely for laboratory, microbiologic, and other diagnostic tests; procedures; antibiotics; and medical supplies used for the diagnosis and treatment of catheter-associated UTIs. Additional days of hospital stay associated with the catheter-associated UTIs were determined. The cost of a coated catheter was $8 more than that of a noncoated catheter. Charges for these associated costs were obtained and tallied to obtain the average cost of catheter-associated UTI at the medical center. The rates of catheter-associated UTIs per 1000 patientdays were analyzed with the Mann-Whitney test.
METHODS A historical hospital-wide baseline nosocomial catheterassociated UTI rate for the University of Massachusetts Medical Center was previously established for noncoated, standard urinary catheters in January 1996 and January 1997. Patient-days of all hospitalized patients were used as the denominator. The medical center began using the silver-hydrogel catheters (Bardex IC Foley catheter; Bard, Covington, Ga) in October 1997. Surveillance for nosocomial catheter-associated UTIs
RESULTS The University of Massachusetts Medical Center is a 375-bed hospital, with about 18% of its beds in intensive care units. It is a tertiary, teaching center. It has medical, surgical, burn, trauma, bone marrow transplant, and pediatric intensive care units. The rates of catheter-associated UTIs for the baseline and evaluation periods are shown in Table 1. The average historical baseline catheter-associated UTI rate was
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Table 2. Cost-estimate of catheter-associated UTIs calculated with hospital charges Cost ($)
Case 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Average Median
Age/Sex
LOS (days)
Cost of extra LOS
Supplies
57/M 19/M 71/F 53/M 83/F 24/F 59/F 86/F 78/M 83/F 75/F 66/M 51/F 44/F 69/F 75/F 58/F 61/F 81/M 63 61
35 45 12 5 9 50 7 8 15 14 30 28 18 15 9 5 5 5 27 18 14
0 0 550.63 487.94 0 0 570.50 550.63 2038.32 2377.58 1977.59 3031.95 0 491.10 0 0 5020.64 1159.76 0 960.88 491.10
0 0 0 0 45.00 0 0 0 0 0 0 0 0 0 0 0 191.01 0 0 12.42 0
Micro Other Diagnostic laboratory laboratory tests 129.40 103.66 51.54 38.29 22.52 217.46 0 38.29 69.52 116.91 96.00 31.37 69.82 127.30 31.37 53.82 64.25 71.74 106.59 75.78 69.52
50.59 44.25 18.48 5.47 11.81 105.35 54.17 9.44 20.67 55.71 18.24 21.94 39.12 5.69 5.82 30.45 617.65 25.34 33.46 61.77 25.34
38.61 0 29.13 0 0 26.91 0 0 26.91 0 0 0 0 30.55 0 26.91 184.65 30.55 107.62 26.41 0
IV/Med
Total cost
136.43 18.96 0 3.25 0 158.61 46.77 15.36 204.28 15.76 60.32 140.20 153.05 0 24.59 0 384.64 9.64 94.06 77.11 24.59
355.03 166.87 649.78 534.95 79.33 508.33 671.44 613.72 2359.70 2565.96 2152.15 3225.46 261.99 654.64 61.78 111.18 6462.84 1297.03 341.73 1214.42 613.72
IV/Med, Intravenous/medications; LOS, length of stay. Average charge of a catheter-associated UTI = $1214.42; median charge = $613.72.
4.9 per 1000 patient-days. The average rate for catheter-associated UTIs during the evaluation period when silver-hydrogel urinary catheters were used was 2.7 per 1000 patient-days, a reduction of 45% (P = .1). Assuming that 43 catheter-associated UTIs were observed monthly when the uncoated catheters were used, the medical center would have 516 catheter-associated UTIs per year. If the silverhydrogel catheters were used, the hospital would have approximately 300 catheter-associated UTIs per year, a total of 216 fewer infections annually.
Cost analysis On the basis of an in-depth cost-analysis of a randomly selected group of patients with catheter-associated UTIs, the average cost (calculated with hospital charges) of a catheter-associated UTI at the medical center was estimated to be $1,214.42 (median, $613.72) (Table 2). The cost of catheter-associated UTIs with the uncoated catheters was $626,640.72 per year compared with $364,326 for the silverhydrogel catheters. Estimated cost for hospital-wide use of the silver-hydrogel urinary catheters was approximately $120,000 annually. This amounted to a net saving of $142,314.72 per year as a result of the reduction in the rate of catheter-associated UTIs
when silver-hydrogel catheters were used. When the median cost of $613.72 per UTI was used, there was a cost-saving of $12,563.52 when the cost of silvercoated catheters was taken into account. On the basis of the estimated cost of a UTI of $839 to $4693.23 from the literature that was then adjusted to 1997 US dollars, the net saving was estimated to be $61,224.00 to $893,737.60.
DISCUSSION When compared with a historical control, the use of silver-hydrogel urinary catheters resulted in a 45% reduction in the incidence of catheter-associated UTIs. The reduction did not reach statistical significance. The cost-analysis showed a cost-saving of $142,314.72 when the average cost of a UTI at this institution was used but only $12,563.52 when the median cost was used. This lower estimation of costsaving is in keeping with the lower–cost-saving estimate of $14,456 (range, $14,456 to $573,293) in the crossover study performed at the University of Virginia Health System with the silver-hydrogel catheters.3 When the literature’s estimated cost of a UTI is used, the cost-saving is estimated to be between $61,262.88 to $893,737.60.
224 Vol. 30 No. 4 Several clinical trials have shown conflicting results with the use of silver-coated catheters.6-10 Saint and colleagues12 performed a meta-analysis to estimate the efficacy of silver-alloy–coated urinary catheters in the prevention of UTI. They found that silver-alloy urinary catheters were significantly more protective against bacteriuria than were silver oxide catheters. Even though silver-alloy catheters cost about $6 more than the standard catheters, they concluded that they may be worth the extra cost given that catheter-associated UTI is the most common nosocomial infection. The more recent clinical trials with silver-hydrogel urinary catheters both in abstract and published forms all indicated a reduction in the incidence of catheter-associated UTI.3,13-16 Verleyen and colleagues15 performed 2 randomized prospective studies to evaluate the incidence of bacteriuria during short- and long-term catheterization with silverhydrogel catheters after urologic procedures compared with the noncoated catheters. They found that there was a significant delay in onset of bacteriuria in patients who underwent short-term catheterization with the silver-hydrogel catheters (median catheterization time, 5 days; range, 2 to 7 days) but found no difference in patients who underwent longterm catheterization (catheterization time, 14 days). Bologna and colleagues16 recently published the results of a multicenter trial with the silver-hydrogel urinary catheter in patients in intensive care units. They found a trend toward a reduction in nosocomial UTIs with the use of the silver-hydrogel catheters, but only in 1 institution was the reduction of statistical significance. The cost-analysis in this institution demonstrated a cost-saving of $98,021. Similarly, Karchmer and colleagues3 showed a reduction in the incidence of UTI and that the silver-coated catheters appeared to be cost-effective, with estimated savings ranging from $14,456 to $537,293. With use of a decision model, Saint et al17 evaluated a simulated cohort of 1000 hospitalized patients receiving general medical, surgical, urologic, and intensive care services and requiring short-term catheterization. With use of the incidence of symptomatic UTI, bacteremia, and direct medical costs as outcomes, they found that the silver-alloy catheters reduced the incidence of symptomatic UTI and bacteremia and resulted in cost-savings. There are several limitations to the current study. It was not a randomized, double-blind, controlled study but a study that compared the rates of catheter-associated UTIs with use of the silver-coated
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catheters with that of a historical control with noncoated catheters. Demographic data and risk factors for UTIs were not gathered for these 2 groups of patients to see whether they were comparable. There might be uncontrolled confounding variables in the 2 patient populations that might affect the results. Secondly, we used hospital-days instead of devicedays as the denominator for UTI rates, and therefore the UTI rates might not be the rates truly attributed to the use of urinary catheters. Thirdly, the health care workers were inserviced before the new catheters were introduced. We tried to minimize the potential bias that might be caused by this education by monitoring for catheter-associated UTIs over several periods, including periods that were far removed from the education sessions. Furthermore, the personnel were not aware of the study. Lastly, extrapolating UTI rates for 2 months to the whole year might not represent the true rates since patient population varied from month to month. However, the catheterassociated UTI rates in the coated group did not vary greatly from month to month, except for March 1998, when the rate was 3.5. The rates of UTI obtained at the beginning of the study were very similar to those at the end after almost 1 year of use. Data for the month of January 1998, during the study period were collected to coincide with the same month of the baseline period to minimize the potential contribution from “the time of the year.” That rate was very similar to the rates of the other study months, with the exception of March 1998. We did not look at the etiologic agents of the catheter-associated UTIs. Maki and colleagues13 found that this catheter was most effective in preventing catheter-associated UTIs caused by enterococci, coagulase-negative staphylococci, and Candida but has little effect on catheter-associated UTIs caused by gram-negative bacilli. However, they still found a reduction, with an overall incidence of 21.2% in the control group and 15.4% in patients with the silver-hydrogel catheters, and concluded that the catheters are a major advance for prevention of catheter-associated UTI. There are several questions that remain unanswered. Do the silver-hydrogel urinary catheters benefit patients catheterized short term versus long term? Verleyen and colleagues15 concluded that they were superior to noncoated catheters in patients with short-term catheterization. However, their study was performed in a very small, specialized group of patients with urologic surgical trauma. Should they be used universally throughout the hospital or
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reserved for patients at high risk for catheter-associated UTI, such as critically ill, elderly, diabetic, and female patients? What about the duration of the effectiveness of the silver coating of the catheters? Some of these questions may best be answered by a large-scale randomized, double-blind, placebo-controlled study involving patients in intensive care and non–intensive care settings and perhaps patients in long-term–care facilities who require urinary catheterization. The authors would like to thank Zita Melvin, Anita Kelley, and Suzanne Hedstrom for data collection.
References 1. Haley RW, Culver DH, White JW, Morgan WM, Emori TG. The nationwide nosocomial infection rate: a new need for vital statistics. Am J Epidemiol 1985;121:159-67. 2. Jarvis WR. Selected aspects of the socioeconomic impact of nosocomial infection: morbidity, mortality, cost, and prevention. Infect Control Hosp Epidemiol 1996;17:552-7. 3. Karchmer TB, Giannetta ET, Muto CA, Strain BA, Farr BM. A randomized crossover study of silver-coated urinary catheters in hospitalized patients. Arch Intern Med 2000;160:3294-8. 4. Public health focus: surveillance, prevention, and control of nosocomial infections. MMWR Morb Mortal Wkly Rep 1992;41:783-7. 5. Saint S. Clinical and economic consequences of nosocomial catheter-related bacteriuria. Am J Infect Control 2000;28:68-75. 6. Schaeffer AJ, Story KO, Johnson SM. Effect of silver oxide/tricholoroisocyanuric acid antimicrobial urinary drainage system on catheter-associated bacteriuria. J Urol 1988;139:69-73.
7. Akiyama H, Okamoto S. Prophylaxis of indwelling urethral catheter infection. Clinical experience with a modified Foley catheter and drainage system. J Urol 1979;121:40-2. 8. Lunderberg T. Prevention of catheter-associated urinary tract infections by use of silver-impregnated catheters. Lancet 1986;2:1031. 9. Johnson JR, Roberts PL, Olsen RJ, Moyer KA, Stamm WE. Prevention of catheter-associated urinary tract infection with a silver oxide-coated urinary catheter: clinical and microbiologic correlates. J Infect Dis 1990;162:1145-50. 10. Liedberg H, Lundberg T, Ekman P. Refinements in the coating of urethral catheters reduce the incidence of catheter-associated bacteriuria. An experimental and clinical study. Eur Urol 1990;17:236-40. 11. Riley DK, Classen DC, Stevens LE, Burke JP. A large randomized clinical trial of silver-impregnated urinary catheter: lack of efficacy and staphylococcal superinfection. Am J Med 1995;98:349-56. 12. Saint S, Elmore JG, Sullivan SD, Emerson SS, Koepsell TD. The efficacy of silver alloy-coated urinary catheters in preventing urinary tract infection: a meta-analysis. Am J Med 1998;105:236-41. 13. Maki DG, Knasinski V, Halvorson K, Tambyah PA. A novel silver-hydrogelimpregnated indwelling urinary catheter reduces CAUTIs: a prospective double-blind trial. [Abstract 10.] Infect Control Hosp Epidemiol 1998;19:682. 14. Ramirez R, Dobin A, Britten E, Wadman S. A silver opportunity for reducing nosocomial urinary tract infections [Abstract S28]. Infect Control Hosp Epidemiol 1998;17:700. 15. Verleyen P, De Ridder D, Van Poppel H, Baert L. Clinical application of the Bardex IC Foley catheter. Eur Urol 1999;36:240-6. 16. Bologna RA, Tu LM, Polansky M, Fraimow HD, Gordon DA, Whitmore KE. Hydrogel-silver ion-coated urinary catheter reduces nosocomial urinary tract infection rates in intensive care unit patients: a multicenter study. Urology 1999;54:982-7. 17. Saint S, Veenstra DL, Sullivan SD, Chenoweth C, Fendrick M. The potential clinical and economic benefits of silver alloy urinary catheters in preventing urinary tract infection. Arch Intern Med 2000;160:2670-5.
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Urinary tract infections (UTIs) account for 40% of all nosocomial infections, and about 80% of these are associated with the use of urinary catheters.1,2 One out of every 4 hospitalized patients receive an indwelling urinary catheter, and the incidence of nosocomial UTIs is approximately 5% per day, with associated bacteremia in 4% of patients.2-4 Excess duration of hospital stay due to nosocomial UTIs has From the University of Massachusetts Medical School and UMass Memorial Medical Center,a Worcester, and Brigham and Women’s Hospital,b Boston. Presented in part at the 37th Annual Meeting of the Infectious Disease Society of America, Philadelphia, Pennsylvania, November 18-21, 1999. Reprint requests: Kwan Kew Lai, DMD, MD, UMass Memorial Medical Center, 55 Lake Avenue North, Worcester, MA 01655. Copyright © 2002 by the Association for Professionals in Infection Control and Epidemiology, Inc. 0196-6553/2002/$35.00 + 0 17/46/120128 doi:10.1067/mic.2002.120128
been estimated to be 1 to 4 additional days, and the estimated average cost of a nosocomial UTI on a nonICU floor is between $680 to $3803 per infection.2,4,5 When adjusted for inflation from 1992 to 1997 with use of the Consumer Price Index for medical care, the estimated cost in 1997 was $839.18 to $4693.23. Therefore, nosocomial UTIs not only contribute to excess morbidity and mortality, but they also significantly add to the cost of hospitalization. Several clinical trials with silver-coated urinary catheters have shown conflicting results. For example, small clinical trials that used silver-oxide–coated urinary catheters resulted in the reduction of the incidence of bacteriuria in selected patients.6-9 Liedberg and colleagues10 found that a silver-alloy and hydrogel-coated urinary catheter significantly reduced bacteriuria after 5 days of catheterization when compared with the noncoated catheters. However, Riley et al11 performed a large randomized clinical trial with silver-impregnated urinary catheters that failed to show prevention of bacteriuria but 221
Lai and Fontecchio
222 Vol. 30 No. 4
Table 1. Rates of nosocomial catheter-associated UTIs with uncoated urinary catheters during the baseline period and the silver-hydrogel urinary catheters during the baseline and evaluation periods Period Baseline (noncoated catheter) Average Evaluation (silver-hydrogel catheter)
Month/Year
No. CAUTIs
Patient-days*
CAUTI Rate/1000 patient-days
48 37 43 23 26 35 21 22 25
8571 8740 8656 8685 9234 9962 8961 8702 9109
5.6 4.2 4.9 2.6 2.8 3.5 2.3 2.5 2.7
1/96 1/97 11/97 1/98 3/98 7/98 8/98
Average CAUTI, Catheter-associated urinary tract infection. *Patient-days = patient-days for entire hospitalized patients.
found a significantly increased incidence of bacteriuria in male patients and a significantly increased incidence of staphylococcal bacteriuria. More recently, Karchmer et al,3 in a randomized, crossover study, reported a reduction in the risk for UTI infection by 21% among study wards in which patients resided randomized to silver-coated catheters and a 32% reduction among patients in whom the catheters were used on the wards. The catheters appeared to offer cost-savings. Given the costs associated with catheter-associated UTIs, decision was made to use silver-coated urinary catheters at the University of Massachusetts Medical Center. These silver-hydrogel catheters provide a hydrophilic coating that inhibits microbial adherence to the catheter surface and migration of bacteria intraluminally and extraluminally.10 Their use began October 1, 1997, and the rates of catheter-associated UTIs after that time were compared with the baseline historical rates associated with uncoated catheters that were collected in January 1996 and January 1997. We performed a cost-benefit analysis to see whether it was cost-effective to use these catheters.
was performed during the evaluation periods in November 1997 and January, March, July, and August 1998 with use of Centers for Disease Control and Prevention-defined criteria for UTIs. The medical records of patients with urine cultures positive for a UTI and urinalyses were reviewed. Patient-days were used to determine nosocomial UTI rates. To estimate the cost of a catheter-associated UTI, all patients with UTI associated with catheters in the month of January 1997 were studied. Because these patients came from all over the hospital, they represented the general population of hospitalized patients. Medical records were reviewed closely for laboratory, microbiologic, and other diagnostic tests; procedures; antibiotics; and medical supplies used for the diagnosis and treatment of catheter-associated UTIs. Additional days of hospital stay associated with the catheter-associated UTIs were determined. The cost of a coated catheter was $8 more than that of a noncoated catheter. Charges for these associated costs were obtained and tallied to obtain the average cost of catheter-associated UTI at the medical center. The rates of catheter-associated UTIs per 1000 patientdays were analyzed with the Mann-Whitney test.
METHODS A historical hospital-wide baseline nosocomial catheterassociated UTI rate for the University of Massachusetts Medical Center was previously established for noncoated, standard urinary catheters in January 1996 and January 1997. Patient-days of all hospitalized patients were used as the denominator. The medical center began using the silver-hydrogel catheters (Bardex IC Foley catheter; Bard, Covington, Ga) in October 1997. Surveillance for nosocomial catheter-associated UTIs
RESULTS The University of Massachusetts Medical Center is a 375-bed hospital, with about 18% of its beds in intensive care units. It is a tertiary, teaching center. It has medical, surgical, burn, trauma, bone marrow transplant, and pediatric intensive care units. The rates of catheter-associated UTIs for the baseline and evaluation periods are shown in Table 1. The average historical baseline catheter-associated UTI rate was
June 2002 223
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Table 2. Cost-estimate of catheter-associated UTIs calculated with hospital charges Cost ($)
Case 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Average Median
Age/Sex
LOS (days)
Cost of extra LOS
Supplies
57/M 19/M 71/F 53/M 83/F 24/F 59/F 86/F 78/M 83/F 75/F 66/M 51/F 44/F 69/F 75/F 58/F 61/F 81/M 63 61
35 45 12 5 9 50 7 8 15 14 30 28 18 15 9 5 5 5 27 18 14
0 0 550.63 487.94 0 0 570.50 550.63 2038.32 2377.58 1977.59 3031.95 0 491.10 0 0 5020.64 1159.76 0 960.88 491.10
0 0 0 0 45.00 0 0 0 0 0 0 0 0 0 0 0 191.01 0 0 12.42 0
Micro Other Diagnostic laboratory laboratory tests 129.40 103.66 51.54 38.29 22.52 217.46 0 38.29 69.52 116.91 96.00 31.37 69.82 127.30 31.37 53.82 64.25 71.74 106.59 75.78 69.52
50.59 44.25 18.48 5.47 11.81 105.35 54.17 9.44 20.67 55.71 18.24 21.94 39.12 5.69 5.82 30.45 617.65 25.34 33.46 61.77 25.34
38.61 0 29.13 0 0 26.91 0 0 26.91 0 0 0 0 30.55 0 26.91 184.65 30.55 107.62 26.41 0
IV/Med
Total cost
136.43 18.96 0 3.25 0 158.61 46.77 15.36 204.28 15.76 60.32 140.20 153.05 0 24.59 0 384.64 9.64 94.06 77.11 24.59
355.03 166.87 649.78 534.95 79.33 508.33 671.44 613.72 2359.70 2565.96 2152.15 3225.46 261.99 654.64 61.78 111.18 6462.84 1297.03 341.73 1214.42 613.72
IV/Med, Intravenous/medications; LOS, length of stay. Average charge of a catheter-associated UTI = $1214.42; median charge = $613.72.
4.9 per 1000 patient-days. The average rate for catheter-associated UTIs during the evaluation period when silver-hydrogel urinary catheters were used was 2.7 per 1000 patient-days, a reduction of 45% (P = .1). Assuming that 43 catheter-associated UTIs were observed monthly when the uncoated catheters were used, the medical center would have 516 catheter-associated UTIs per year. If the silverhydrogel catheters were used, the hospital would have approximately 300 catheter-associated UTIs per year, a total of 216 fewer infections annually.
Cost analysis On the basis of an in-depth cost-analysis of a randomly selected group of patients with catheter-associated UTIs, the average cost (calculated with hospital charges) of a catheter-associated UTI at the medical center was estimated to be $1,214.42 (median, $613.72) (Table 2). The cost of catheter-associated UTIs with the uncoated catheters was $626,640.72 per year compared with $364,326 for the silverhydrogel catheters. Estimated cost for hospital-wide use of the silver-hydrogel urinary catheters was approximately $120,000 annually. This amounted to a net saving of $142,314.72 per year as a result of the reduction in the rate of catheter-associated UTIs
when silver-hydrogel catheters were used. When the median cost of $613.72 per UTI was used, there was a cost-saving of $12,563.52 when the cost of silvercoated catheters was taken into account. On the basis of the estimated cost of a UTI of $839 to $4693.23 from the literature that was then adjusted to 1997 US dollars, the net saving was estimated to be $61,224.00 to $893,737.60.
DISCUSSION When compared with a historical control, the use of silver-hydrogel urinary catheters resulted in a 45% reduction in the incidence of catheter-associated UTIs. The reduction did not reach statistical significance. The cost-analysis showed a cost-saving of $142,314.72 when the average cost of a UTI at this institution was used but only $12,563.52 when the median cost was used. This lower estimation of costsaving is in keeping with the lower–cost-saving estimate of $14,456 (range, $14,456 to $573,293) in the crossover study performed at the University of Virginia Health System with the silver-hydrogel catheters.3 When the literature’s estimated cost of a UTI is used, the cost-saving is estimated to be between $61,262.88 to $893,737.60.
224 Vol. 30 No. 4 Several clinical trials have shown conflicting results with the use of silver-coated catheters.6-10 Saint and colleagues12 performed a meta-analysis to estimate the efficacy of silver-alloy–coated urinary catheters in the prevention of UTI. They found that silver-alloy urinary catheters were significantly more protective against bacteriuria than were silver oxide catheters. Even though silver-alloy catheters cost about $6 more than the standard catheters, they concluded that they may be worth the extra cost given that catheter-associated UTI is the most common nosocomial infection. The more recent clinical trials with silver-hydrogel urinary catheters both in abstract and published forms all indicated a reduction in the incidence of catheter-associated UTI.3,13-16 Verleyen and colleagues15 performed 2 randomized prospective studies to evaluate the incidence of bacteriuria during short- and long-term catheterization with silverhydrogel catheters after urologic procedures compared with the noncoated catheters. They found that there was a significant delay in onset of bacteriuria in patients who underwent short-term catheterization with the silver-hydrogel catheters (median catheterization time, 5 days; range, 2 to 7 days) but found no difference in patients who underwent longterm catheterization (catheterization time, 14 days). Bologna and colleagues16 recently published the results of a multicenter trial with the silver-hydrogel urinary catheter in patients in intensive care units. They found a trend toward a reduction in nosocomial UTIs with the use of the silver-hydrogel catheters, but only in 1 institution was the reduction of statistical significance. The cost-analysis in this institution demonstrated a cost-saving of $98,021. Similarly, Karchmer and colleagues3 showed a reduction in the incidence of UTI and that the silver-coated catheters appeared to be cost-effective, with estimated savings ranging from $14,456 to $537,293. With use of a decision model, Saint et al17 evaluated a simulated cohort of 1000 hospitalized patients receiving general medical, surgical, urologic, and intensive care services and requiring short-term catheterization. With use of the incidence of symptomatic UTI, bacteremia, and direct medical costs as outcomes, they found that the silver-alloy catheters reduced the incidence of symptomatic UTI and bacteremia and resulted in cost-savings. There are several limitations to the current study. It was not a randomized, double-blind, controlled study but a study that compared the rates of catheter-associated UTIs with use of the silver-coated
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catheters with that of a historical control with noncoated catheters. Demographic data and risk factors for UTIs were not gathered for these 2 groups of patients to see whether they were comparable. There might be uncontrolled confounding variables in the 2 patient populations that might affect the results. Secondly, we used hospital-days instead of devicedays as the denominator for UTI rates, and therefore the UTI rates might not be the rates truly attributed to the use of urinary catheters. Thirdly, the health care workers were inserviced before the new catheters were introduced. We tried to minimize the potential bias that might be caused by this education by monitoring for catheter-associated UTIs over several periods, including periods that were far removed from the education sessions. Furthermore, the personnel were not aware of the study. Lastly, extrapolating UTI rates for 2 months to the whole year might not represent the true rates since patient population varied from month to month. However, the catheterassociated UTI rates in the coated group did not vary greatly from month to month, except for March 1998, when the rate was 3.5. The rates of UTI obtained at the beginning of the study were very similar to those at the end after almost 1 year of use. Data for the month of January 1998, during the study period were collected to coincide with the same month of the baseline period to minimize the potential contribution from “the time of the year.” That rate was very similar to the rates of the other study months, with the exception of March 1998. We did not look at the etiologic agents of the catheter-associated UTIs. Maki and colleagues13 found that this catheter was most effective in preventing catheter-associated UTIs caused by enterococci, coagulase-negative staphylococci, and Candida but has little effect on catheter-associated UTIs caused by gram-negative bacilli. However, they still found a reduction, with an overall incidence of 21.2% in the control group and 15.4% in patients with the silver-hydrogel catheters, and concluded that the catheters are a major advance for prevention of catheter-associated UTI. There are several questions that remain unanswered. Do the silver-hydrogel urinary catheters benefit patients catheterized short term versus long term? Verleyen and colleagues15 concluded that they were superior to noncoated catheters in patients with short-term catheterization. However, their study was performed in a very small, specialized group of patients with urologic surgical trauma. Should they be used universally throughout the hospital or
June 2002 225
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reserved for patients at high risk for catheter-associated UTI, such as critically ill, elderly, diabetic, and female patients? What about the duration of the effectiveness of the silver coating of the catheters? Some of these questions may best be answered by a large-scale randomized, double-blind, placebo-controlled study involving patients in intensive care and non–intensive care settings and perhaps patients in long-term–care facilities who require urinary catheterization. The authors would like to thank Zita Melvin, Anita Kelley, and Suzanne Hedstrom for data collection.
References 1. Haley RW, Culver DH, White JW, Morgan WM, Emori TG. The nationwide nosocomial infection rate: a new need for vital statistics. Am J Epidemiol 1985;121:159-67. 2. Jarvis WR. Selected aspects of the socioeconomic impact of nosocomial infection: morbidity, mortality, cost, and prevention. Infect Control Hosp Epidemiol 1996;17:552-7. 3. Karchmer TB, Giannetta ET, Muto CA, Strain BA, Farr BM. A randomized crossover study of silver-coated urinary catheters in hospitalized patients. Arch Intern Med 2000;160:3294-8. 4. Public health focus: surveillance, prevention, and control of nosocomial infections. MMWR Morb Mortal Wkly Rep 1992;41:783-7. 5. Saint S. Clinical and economic consequences of nosocomial catheter-related bacteriuria. Am J Infect Control 2000;28:68-75. 6. Schaeffer AJ, Story KO, Johnson SM. Effect of silver oxide/tricholoroisocyanuric acid antimicrobial urinary drainage system on catheter-associated bacteriuria. J Urol 1988;139:69-73.
7. Akiyama H, Okamoto S. Prophylaxis of indwelling urethral catheter infection. Clinical experience with a modified Foley catheter and drainage system. J Urol 1979;121:40-2. 8. Lunderberg T. Prevention of catheter-associated urinary tract infections by use of silver-impregnated catheters. Lancet 1986;2:1031. 9. Johnson JR, Roberts PL, Olsen RJ, Moyer KA, Stamm WE. Prevention of catheter-associated urinary tract infection with a silver oxide-coated urinary catheter: clinical and microbiologic correlates. J Infect Dis 1990;162:1145-50. 10. Liedberg H, Lundberg T, Ekman P. Refinements in the coating of urethral catheters reduce the incidence of catheter-associated bacteriuria. An experimental and clinical study. Eur Urol 1990;17:236-40. 11. Riley DK, Classen DC, Stevens LE, Burke JP. A large randomized clinical trial of silver-impregnated urinary catheter: lack of efficacy and staphylococcal superinfection. Am J Med 1995;98:349-56. 12. Saint S, Elmore JG, Sullivan SD, Emerson SS, Koepsell TD. The efficacy of silver alloy-coated urinary catheters in preventing urinary tract infection: a meta-analysis. Am J Med 1998;105:236-41. 13. Maki DG, Knasinski V, Halvorson K, Tambyah PA. A novel silver-hydrogelimpregnated indwelling urinary catheter reduces CAUTIs: a prospective double-blind trial. [Abstract 10.] Infect Control Hosp Epidemiol 1998;19:682. 14. Ramirez R, Dobin A, Britten E, Wadman S. A silver opportunity for reducing nosocomial urinary tract infections [Abstract S28]. Infect Control Hosp Epidemiol 1998;17:700. 15. Verleyen P, De Ridder D, Van Poppel H, Baert L. Clinical application of the Bardex IC Foley catheter. Eur Urol 1999;36:240-6. 16. Bologna RA, Tu LM, Polansky M, Fraimow HD, Gordon DA, Whitmore KE. Hydrogel-silver ion-coated urinary catheter reduces nosocomial urinary tract infection rates in intensive care unit patients: a multicenter study. Urology 1999;54:982-7. 17. Saint S, Veenstra DL, Sullivan SD, Chenoweth C, Fendrick M. The potential clinical and economic benefits of silver alloy urinary catheters in preventing urinary tract infection. Arch Intern Med 2000;160:2670-5.
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