|
The potential clinical and economic benefits of silver alloy urinary catheters in preventing urinary tract infection |
Saint S, Veenstra D L, Sullivan S D, Chenoweth C, Fendrick A M |
|
|
Record Status This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Silver alloy catheters in hospitalised patients requiring short-term urinary catheterisation.
Economic study type Cost-effectiveness analysis.
Study population The study population was a hypothetical cohort of patients admitted to hospitals on general medical, surgical, urological, and intensive care wards requiring the short-term use (2-10 days) of indwelling urethral catheters. This cohort was chosen because most patients in the clinical trials evaluating the effectiveness of silver-coated catheters belonged to these groups, 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 catheterisation in the trials was approximately 7 day (range: 3 - 21 days).
Setting The setting was a hospital. The economic analysis was carried out in the USA.
Dates to which data relate Effectiveness data were obtained from literature published between 1981 and 1998. The estimation of some of the resource use data (such as the increased hospital days attributed to symptomatic urinary tract infection (UTI) and bacteremia) was based on data from literature published between 1980 and 1992. The price year was 1998.
Source of effectiveness data The evidence for the effectiveness outcomes was based on a literature review.
Modelling A decision-analytic model (using DATA 3.5; Treeage) was developed to estimate the costs and effects associated with each preventive strategy. The time horizon of the model was the period of hospitalisation.
Outcomes assessed in the review The outcomes obtained from the literature were as follows:
probability of receiving systemic antimicrobial agents;
probability of developing bacteriuria in the control group (patients not receiving systemic antimicrobial agents and given standard noncoated catheters for 2-10 days);
probability of developing symptomatic UTI without bacteremia after developing bacteriuria;
probability of bacteremia after developing bacteriuria;
probability of remaining asymptomatic and not requiring treatment after developing bacteriuria;
relative risk of bacteriuria if receiving systemic antimicrobial agents;
relative risk of bacteriuria if given silver alloy catheters.
Study designs and other criteria for inclusion in the review It was reported that the relative risk reduction of bacteriuria (or protective effect) associated with antimicrobial use was derived from 5 studies that adjusted for several factors (such as sex and duration of catheterisation) that might affect the probability of developing bacteriuria. The relative risk reduction (or protective effect) associated with silver catheter use came from a meta-analysis of 5 randomised controlled trials. The baseline risk of bacteriuria over the hospital stay in the control group was statistically pooled from several prospective studies.
Sources searched to identify primary studies Criteria used to ensure the validity of primary studies Methods used to judge relevance and validity, and for extracting data Number of primary studies included A total of 17 studies, including a meta-analysis of 5 randomised controlled trials were used.
Methods of combining primary studies A meta-analysis of 5 randomised trials was used. Quantitative pooling of data from other studies was undertaken. Quantitative pooling was performed for several variables, in which case the base-case estimate was the summary estimate, with the range representing the 95% confidence intervals. However, for some variables this range was broadened.
Investigation of differences between primary studies Results of the review The baseline values (range used in sensitivity analyses) for the outcomes were:
probability of receiving systemic antimicrobial agents, 0.80 (0.65 - 0.97);
probability of developing bacteriuria in the control group, 0.26 (0.18 - 0.34);
probability of developing symptomatic UTI without bacteremia after developing bacteriuria, 0.24 (0.08 - 0.35);
probability of bacteremia after developing bacteriuria, 0.04 (0 - 0.06);
probability of remaining asymptomatic and not requiring treatment after developing bacteriuria, 0.72 (0.56 - 0.92);
relative risk of bacteriuria if receiving systemic antimicrobial agents, 0.35 (65% relative risk reduction) (0.27 - 0.47);
relative risk of bacteriuria if given silver alloy catheters, 0.55 (45% relative risk reduction) (0.38 - 0.72).
Measure of benefits used in the economic analysis The measure of benefits was the incidence of symptomatic UTI and bacteremia for a hypothetical cohort of 1,000 patients.
Direct costs Costs were not discounted because of the short time frame of the cost analysis. Some resource use data were reported separately. Cost items were reported separately. The cost analysis covered the costs of silver alloy catheter tray, standard catheter tray, urinalysis, urine culture and sensitivity, blood culture, day on inpatient ward, and antimicrobial agents. Cost estimates were obtained from a number of different sources. Cost-to-charge ratio was used to convert the Current Procedural Terminology-based charges to costs. All costs were given in 1998 US dollars. The cost estimates of the study were conservative in that they did not include the extra costs associated with physician or nursing time and routine blood tests (complete blood cell count or chemistry panels) and only included the minimum number of laboratory tests and antimicrobial regimens required to diagnose and treat symptomatic UTI or bacteremia in a patient.
Statistical analysis of costs Costs were treated stochastically and the uncertainty surrounding the parameters was investigated through probabilistic sensitivity analysis using Monte-Carlo simulation. The distributions assigned to the costs were not reported.
Indirect Costs Indirect costs were not included.
Sensitivity analysis A set of one-way sensitivity analyses was performed on the input parameters. Threshold values for the influential parameters were reported. A dynamic sensitivity analysis was also conducted using Monte Carlo simulation to assess the effect of uncertainty in all of the variables simultaneously.
Estimated benefits used in the economic analysis 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 1,000 patients (number needed to treat = 74) and a 44% relative decrease in the incidence of bacteremia from 4.5 to 2.5 cases per 1,000 patients (number needed to treat = 500) compared with standard catheters.
Cost results The use of silver alloy catheters resulted in estimated cost savings of $4.09 per patient compared with standard catheter use ($20.87 versus $16.78).
Synthesis of costs and benefits Costs and benefits were not combined since the silver-coated catheter strategy was the dominant strategy. The one-way sensitivity analyses revealed that this strategy remained dominant throughout the ranges evaluated. In the 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 patients.
Authors' conclusions Using silver alloy catheters in hospitalised patients requiring short-term urinary catheterisation reduces the incidence of symptomatic UTI and bacteremia, and is likely to produce cost savings compared with standard catheters.
CRD COMMENTARY - Selection of comparators A justification was given for the choice of the comparator. It was stated to be the standard procedure in the context in question. You, as a database user, should consider whether this is a relevant health technology in your own setting.
Validity of estimate of measure of benefit The internal validity of the effectiveness data is likely to be high given the use of a meta-analysis of randomised trials, and prospective studies, where available. However, more information on the sources searched to identify the literature review, and the methods used to quality appraise the review and other studies would have been helpful.
Validity of estimate of measure of benefit:
The estimation of benefits was modelled. The instrument used to derive a measure of health benefit, a decision-analytic model, was appropriate for the study question.
Validity of estimate of costs Positive aspects of the cost analysis were that adequate details of the methods of cost estimation were given and it appears that all important direct cost elements were included in the cost analysis. Moreover, some quantities were reported separately from costs, the price year and the perspective adopted in the cost analysis were specified, and the cost calculations were based on true costs rather than charges, although they were based on cost-to-charge ratio rather than on direct measurement of actual costs. In addition, sensitivity analysis was performed on cost data and the cost data was treated stochastically. However, the effects of alternative procedures on indirect costs were not addressed.
Other issues The authors' conclusions appear to be justified given the extensive sensitivity analysis performed. The issue of generalisability was addressed by noting that the results of this study are not generalisable to all patients requiring indwelling catheters. The use of silver-coated catheters in those requiring catheterisation for less than two days (for example in the case of peripartum or some postoperative patients) and in those requiring long-term catheterisation (for example, patients with spinal cord injury) may not lead to cost savings. Appropriate comparisons with other economic evaluations were not reported. Further limitations of the study acknowledged by the authors were that all of the trials included in this study used bacteriuria as an outcome measure rather than symptomatic UTI or bacteremia. Studies evaluating those outcomes would be helpful for a more precise determination of the ultimate clinical benefit of silver catheters, but would require many patients.
Implications of the study The authors make detailed suggestions. To make the most effective use of this new catheter, health care systems should estimate the average duration of catheterisation for patients admitted to the different hospital wards, providing either silver-coated or standard catheters. This study found that most indwelling catheters were used between 2 and 10 days in all catheterised 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 in the obstetric ward and in the operating room. Further studies are needed to identify more clearly those patient groups likely to derive the greatest benefit from silver-coated catheters. However, given the difficulties in preventing catheter-related UTI and the potential clinical and economic benefit associated with silver alloy catheters, this relatively simple intervention, the authors suggested, should be strongly considered in the appropriate clinical settings.
Bibliographic details Saint S, Veenstra D L, Sullivan S D, Chenoweth C, Fendrick A M. The potential clinical and economic benefits of silver alloy urinary catheters in preventing urinary tract infection. Archives of Internal Medicine 2000; 160: 2670-2675 Indexing Status Subject indexing assigned by NLM MeSH Alloys; Anti-Infective Agents /therapeutic use; Bacteremia /etiology; Cost-Benefit Analysis; Decision Making; Decision Trees; Hospital Costs; Hospitalization /economics; Humans; Incidence; Monte Carlo Method; Multivariate Analysis; Outcome Assessment (Health Care); Risk; Sensitivity and Specificity; Silver; United States; Urinary Catheterization /adverse effects /economics /instrumentation; Urinary Tract Infections /complications /economics /etiology /prevention & control AccessionNumber 22000008293 Date bibliographic record published 31/01/2002 Date abstract record published 31/01/2002 |
|
|
|