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Antimicrobial prophylaxis prior to shock wave lithotripsy in patients with sterile urine before treatment: a meta-analysis and cost-effectiveness analysis |
Pearle M S, Roehrborn C G |
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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 Antimicrobial prophylaxis prior to shock wave lithotripsy (SWL) in patients with sterile urine before treatment.
Economic study type Cost-effectiveness analysis.
Study population A hypothetical cohort of male and female patients with sterile urine cultures prior to treatment.
Setting Hospital. The economic study was carried out in Dallas, Texas.
Dates to which data relate The main effectiveness data were taken from previously published studies (randomized controlled trials and clinical series) published between 1988 and 1995. Resource and cost data were mainly derived from 1988-96 sources. The price year was not stated.
Source of effectiveness data The incidence of post-SWL urinary tract infection (UTI), probability of a post-SWL UTI and relative risk of post-SWL UTI were based on a review of previously completed studies.
Outcomes assessed in the review The outcomes assessed were incidence of post-SWL urinary tract infection (UTI), median probability of a post-SWL UTI andrelative risk of post-SWL UTI. The risk of serious UTIs resulting in inpatient treatment was also included in the analysis.
Study designs and other criteria for inclusion in the review All available studies (RCTs and non-RCTs) in the literature regarding antibiotic prophylaxis prior to SWL in patients with sterile urine cultures prior to treatment were selected. Articles were excluded from the analysis if either raw data were not provided or subgroup analysis was incomplete.
Sources searched to identify primary studies MEDLINE was searched and additional relevant literature was obtained by reviewing the reference lists for the articles selected from the MEDLINE search.
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 14 studies were included in the review.
Methods of combining primary studies Investigation of differences between primary studies The authors investigated the differences between the primary studies focussing on the differences in the number of patients in treatment and non-treatment arms, stone location, mean stone size, endoscopic manipulation prior to SWL, type of lithotriptor, type of anaesthesia, prophylactic antimicrobial regimen, timing of the urine culture after SWL and definition of positive culture.
Results of the review Bayesian meta-analysis determined a 2.1% (95% CI: 0.9% - 3.6%)and 5.7% (95% CI: 3.8% - 8.4%) median risk of urinary tract infection for the with and without prophylaxis groups, respectively. The relative risk of post-SWL UTIs with prophylaxis versus without prophylaxis was 0.45 (95% CI: 0.22 - 0.93, p=0.0005). The risk of serious UTIs resulting in inpatient treatment was 0.1% for prophylaxis and 0.3% for no prophylaxis).
Measure of benefits used in the economic analysis No summary benefits measure was identified. As such the benefits were assumed to be equivalent to efficient outcomes. The measure of benefits was the incidence of post-SWL urinary tract infection (UTI)), median probability of a post-SWL UTI, relative risk of post-SWL UTI and the risk of serious UTIs resulting in inpatient treatment.
Direct costs Treatment schedule (7-days SMX/TMP DS po bid, 7-days Cipro 500mg po bid, IV gentamicin) and different prophylactic regimens (SMX/TMP DS X 3 days, Cipro 500mg X 1, IV gentamicin X 1) costs were included in the analysis. The quantities were analysed separately from the costs. Discounting was not relevant to the time scale of the study. The quantity/cost boundary adopted was the hospital. The price year was not stated.
Statistical analysis of costs Median plus confidence intervals.
Sensitivity analysis No sensitivity analysis was conducted.
Estimated benefits used in the economic analysis Bayesian meta-analysis determined a 2.1% (95% CI: 0.9% - 3.6%)and 5.7% (95% CI: 3.8% - 8.4%) median risk of urinary tract infection for the with and without prophylaxis groups, respectively. The relative risk of post-SWL UTIs with prophylaxis versus without prophylaxis was 0.45 (95% CI: 0.22 - 0.93, p=0.0005). The risk of serious UTIs resulting in inpatient treatment was 0.1% for prophylaxis and 0.3% for no prophylaxis).
Cost results The prophylaxis (SMX/TMP x 3 days, Cipro 500 mg x 1, IV gentamicin x 1) and treatment costs (per 1000 patients) were $3,084.00, $3,934.00 and $ 40,294.00($7,009.06, $7,859.06 and $44,219.06 inclusive of the risk of serious UTIs resulting in inpatient treatment) and $4,054, $4,904 and $41,264 ($7,979.26, $8,829.26 and $54,189.26 inclusive of the risk of serious UTIs resulting in inpatient treatment) in the 7-days SMX/TMP DS po bid and7-days Cipro 500mg po bid, respectively. The treatment for UTI only costs were $391 ($12,166.02 inclusive of the risk of serious UTIs resulting in inpatient treatment) and $3,024 ($14,799.42 inclusive of the risk of serious UTIs resulting in inpatient treatment) in the 7-days SMX/TMP DS po bid and7-days Cipro 500mg po bid, respectively. The cost of SWL is estimated to be $8,000 per patient.
Synthesis of costs and benefits A synthesis of the estimated benefits and costs was not provided. An incremental analysis was performed. The incremental cost per 1,000 patients was estimated to range from$1,029 to $39,903 for the three prophylaxis regimens within two schedules of 7-days SMX/TMP DS po bid, 7-days Cipro 500mg po bid. For the same three prophylaxis regimens and schedules, but taking into account the risk of serious UTIs resulting in inpatient treatment, the incremental costs ranged from -$6,820 to $32,053. In other words for some strategies there was a net cost and for those which took into account inpatient treatment there was, for some regimens, a cost saving.
Authors' conclusions Antibiotic prophylaxis prior to SWL in patients with sterile pretreatment urine cultures was shown to be efficacious in reducing the rate of post-SWL UTIs. The exclusion of inpatient episodes for sepsis and acute pyelonephritis, however,makes the strategy no longer cost-effective. The prophylaxis becomes both efficacious and cost-effective (i.e. the dominant strategy), by using literature-derived incidence estimates for post-SWL urosepsis or pyelonephritis necessitating inpatient treatment.
CRD COMMENTARY - Selection of comparators The reason for the choice of the comparator is clear. The use of preoperative antimicrobial agents to avoid high and low-risk complications associated with SWL patients is a common prophylactic approach. It should be noted, however, that the authors were not able to comment upon the efficacy of anysingle regimen as the literature review involved eight different prophylactic regimens. You, asuser of this database, should consider whether these are widely used health technologies in your setting.
Validity of estimate of measure of benefit The estimate of measure of benefit used in the economic analysis is likely to be internally valid and the data do not appear to have been used selectively. A benefit measure which considered quality of life and health states such as febrile days would, however,have enhanced the validity of the benefits.
Validity of estimate of costs The resource quantities were reported separately from the prices. Adequate details of methods of quantity/cost estimation were given. Important costs do not appear to have been omitted.
Other issues The authors' conclusions are likely to be justified, given the uncertainties in the data. The issue of generalisability to other settings or countries was addressed and appropriate comparisons made with other studies. The results do not appear to have been presented selectively.
Implications of the study More research is required to compare the efficacy of various prophylactic regimens in order to identify an inexpensive but effective approach.
Bibliographic details Pearle M S, Roehrborn C G. Antimicrobial prophylaxis prior to shock wave lithotripsy in patients with sterile urine before treatment: a meta-analysis and cost-effectiveness analysis. Urology 1997; 49(5): 679-686 Indexing Status Subject indexing assigned by NLM MeSH Antibiotic Prophylaxis /economics; Cost-Benefit Analysis; Humans; Lithotripsy /adverse effects /economics; Urinary Tract Infections /epidemiology /etiology /prevention & Urine /microbiology; control AccessionNumber 21997000689 Date bibliographic record published 31/12/1998 Date abstract record published 31/12/1998 |
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