Management of ureteral calculi: a cost comparison and decision making analysis Lotan Y, Gettman M T, Roehrborn C G, Cadeddu J A, Pearle M S 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 The use of observation (OBS), ureteroscopy (URS), or shock wave lithotripsy (ESWL) for the treatment of patients with ureteral calculi. Type of intervention Treatment. Economic study type Cost-effectiveness analysis. Study population The study population comprised a hypothetical patient with a ureteral stone at any location, which required treatment, and who was an adequate candidate for OBS, URS, or ESWL. Setting The setting was outpatient secondary care. The economic study was carried out in Texas, USA. Dates to which data relate The effectiveness data were derived from studies published between 1986 and 1999. No dates for the collection of resource use data were reported. The costs were estimated in 1998, 2000 and 2001 values, but a price year was not reported. Source of effectiveness data The effectiveness evidence came from a review of published studies and authors' assumptions. Modelling A decision tree model was constructed to evaluate the total costs associated with the three treatments for ureteral calculi (initial treatment and follow-up care). The time horizon of the model was not reported, nor was the length of follow-up. Secondary, tertiary and quaternary treatment options after failure were considered, as were different stone locations (proximal, mid and distal ureter). Outcomes assessed in the review The outcomes assessed in the review were the success rates (percentage of stone-free patients) associated with the three treatments, stratified by location (proximal, mid and distal ureter). Two ESWL options, HM3 and other, were considered. Page: 1 / 5
Study designs and other criteria for inclusion in the review The authors did not state the design of each primary study included in the review, but described some of them (a metaanalysis). No specific inclusion or exclusion criteria were reported. Sources searched to identify primary studies MEDLINE was searched from 1966 to publication of the article, to identify relevant primary studies. For URS, the search was limited to articles published in the last decade due to recent developments in the technique. 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 Sixty-one primary studies were included in the review. Methods of combining primary studies The method used to combine the primary studies (weighted average) was reported only for URS and ESWL. Investigation of differences between primary studies Results of the review For the proximal ureter, the percentage of stone-free patients was 12% (range: 6-22) with OBS, 80% (range: 66-99) with URS, 83% (range: 73-96) with HM3 ESWL, and 84% (range: 59-96) with other ESWL. For the mid ureter, the percentage of stone-free patients was 22% (range: 0-46) with OBS, 92% (range: 75-100) with URS, 89% (range: 53-97) with HM3 ESWL, and 78% (range: 51-92) with other ESWL. For the distal ureter, the percentage of stone-free patients was 45% (range: 36-71) with OBS, 95% (range: 86-100) with URS, 89% (range: 78-97) with HM3 ESWL, and 82% (range: 59-97) with other ESWL. Methods used to derive estimates of effectiveness The authors made some assumptions that were used both to derive the effectiveness estimates and to construct the decision tree. Estimates of effectiveness and key assumptions It was assumed that: following the failure of any of the three treatments, an open or laparoscopic procedure was performed with 100% success; the success rate per treatment modality was linear (i.e. the success rate was the same independently of whether the treatment was initial or secondary); Page: 2 / 5
after two ESWL failures, URS was performed at least once before resorting to an open procedure; and all patients who underwent URS, but none who underwent ESWL, had a stent placed at the end of the procedure. Measure of benefits used in the economic analysis No summary benefit measure was used in the economic evaluation. The analysis is therefore classified as a costconsequences analysis. Direct costs Discounting was not conducted. However, it was unclear whether it was relevant since the time horizon of the model was not reported. The unit costs were not analysed separately from the quantities of resources. The health services included in the economic evaluation were operating room, operating room supplies, day surgery, recovery room, laboratory costs, professional fees, anaesthesia costs and emergency room visits. Complications were not considered in the analysis because the incidence was low. The costs of the initial diagnosis were not included since they were considered to be identical in the three treatment groups. The cost/resource boundary adopted in the study was not explicitly stated, but it appears that the direct costs have been estimated from the perspective of the health care payer. The costs were estimated using Medicare reimbursement rates for professional fees and data from a large metropolitan county hospital in Dallas (TX) for hospital costs. Resource use was derived from published data and the authors' assumptions. The price year was not stated. Statistical analysis of costs The costs were treated deterministically. Indirect Costs The indirect costs (i.e. productivity losses) were included in the analysis, only in the observation branch of the decision tree. They were estimated from the 1998 Census of Population and Housing from the United States Census Bureau. The average American worker wage was $105 in 1998 dollars. The source of lost days was not reported. No discounting was carried out. Currency US dollars ($). Sensitivity analysis One- and two-way sensitivity analyses were conducted to address the issue of variability in the data. The model inputs varied were the success rates and individual costs. Threshold analyses were also conducted. Finally, a two-way sensitivity analysis was used to create a universal table comparing the treatment costs of URS and ESWL at various individual treatment costs and success rates. The ranges used were those derived from the literature. Estimated benefits used in the economic analysis See the 'Effectiveness Results' section. Cost results For proximal ureteral stones, the total costs were $2,943 with OBS, $3,344 with URS, $4,819 with HM3 ESWL, and $4,784 with other ESWL. For mid ureteral stones, the total costs were $2,245 with OBS, $2,878 with URS, $4,545 with HM3 ESWL, and $4,865 Page: 3 / 5
with other ESWL. For distal ureteral stones, the total costs were $1,532 with OBS, $2,785 with URS, $4,533 with HM3 ESWL, and $4,729 with other ESWL. Sensitivity analyses demonstrated that URS remained the least costly option under a variety of scenarios. From the threshold analysis, the costs of URS would have to increase by more than $1,400 (proximal), $1,700 (mid) or $1,850 (distal), and the success rate would have to decrease by more than 28% (proximal), 36% (mid) or 39% (distal), before cost equivalence between ESWL and URS would be achieved. Synthesis of costs and benefits The costs and benefits were not combined. Authors' conclusions Ureteroscopy (URS) represented the cheapest treatment strategy for ureteral calculi at all locations when observation (OBS) failed. Since the selection of the treatment strategy depends not only on the costs, but also on other factors (e.g. stone size, patient preferences and surgeon skills), the authors provided a table to enable individual surgeons and decisions-makers to determine the appropriate cost impact of each treatment strategy given institution-specific characteristics (procedural cost and success rate). CRD COMMENTARY - Selection of comparators The authors stated that several treatment strategies were available for patients suffering from ureteral calculi. The authors did not explicitly justify their choice of the comparators, but the three procedures considered in the study were likely to represent the most commonly used treatment options. You should decide whether they represent valid comparators in your own setting. Validity of estimate of measure of effectiveness The analysis of effectiveness used a review of the literature. However, the methods and conduct of the review were not reported satisfactorily. The designs of the primary studies were not described and details of the sample populations and clinical characteristics (e.g. stone size and patient co-morbidities) were not reported. The method used to combine the primary studies was only reported for some of the techniques. Further, the issue of the validity of the primary studies was not addressed. Some outcome measures that were unavailable in the literature were derived from authors' assumptions, and this introduced more uncertainty. However, extensive sensitivity analyses were conducted to deal with uncertainty and variability in the data. Validity of estimate of measure of benefit No summary benefit measure was used in the analysis. A cost-consequences analysis was therefore conducted. Validity of estimate of costs The perspective adopted in the study was not explicitly stated. The direct costs were estimated from the payer perspective and the indirect costs were considered for one strategy only. Thus, it is difficult to confirm that a societal perspective was adopted. If this were the case, productivity losses would have been included in all of the treatment strategies. It was likely that indirect costs were also incurred under other approaches. The rationale for the approach adopted was unclear. The source of the data was reported for the costs but not for resource use. The price year was also not reported, thus hindering reflation exercises in other settings. The unit costs and resource use were not provided separately, which may hinder the generalisability to other settings. Sensitivity analyses were conducted to address the issue of variability in the data, but the costs were treated Page: 4 / 5
Powered by TCPDF (www.tcpdf.org) deterministically in the base-case. Thus, the cost estimates appear to have been specific to the study setting and only the total costs were varied. The authors acknowledged that the costs might vary across institutions. The length of follow-up was not reported and it was not possible to assess the relevance of discounting. Some assumptions about resource use were made in the decision model, but these were not justified. Some categories of costs were explicitly excluded from the economic evaluation, although the authors justified this. The authors stated that variations in average wages might dramatically shift the threshold point at which cost equivalence between OBS and the remaining strategy is achieved. Other issues The authors made some comparisons of their findings with those from other studies, but differences in stone size were found in the literature. In addition, OBS was not considered a valid option in most of the studies. Some limitations of the study were noted and discussed. For example, the authors noted that it was assumed that all procedures were carried out in an outpatient setting, but a small fraction of the patients could require inpatient hospitalisation. However, the inclusion of such costs was unlikely to change the conclusions of the analysis. Finally, most of the assumptions made in the decision model (for both effectiveness and costs) may not be realistic under institution-specific scenarios. Implications of the study The study results suggested that OBS is the cheapest strategy for treating patients with ureteral calculi, but if low success rates are observed then URS represents an alternative efficient option. Source of funding None stated. Bibliographic details Lotan Y, Gettman M T, Roehrborn C G, Cadeddu J A, Pearle M S. Management of ureteral calculi: a cost comparison and decision making analysis. Journal of Urology 2002; 167(4): 1621-1629 PubMedID 11912376 Indexing Status Subject indexing assigned by NLM MeSH Cost-Benefit Analysis; Decision Trees; Humans; Ureteral Calculi /economics /therapy AccessionNumber 22002000613 Date bibliographic record published 31/05/2004 Date abstract record published 31/05/2004 Page: 5 / 5