Cost perspectives of laparoscopic and open appendectomy Moore D E, Speroff T, Grogan E, Poulose B, Holzman M D

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1 Cost perspectives of laparoscopic and open appendectomy Moore D E, Speroff T, Grogan E, Poulose B, Holzman M D 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 laparoscopic appendectomy for the treatment of acute appendicitis. Type of intervention Treatment. Economic study type Cost-effectiveness analysis. Study population The target population included patients with acute appendicitis. Setting The setting was tertiary care. The economic study was carried out in Tennessee, USA. Dates to which data relate The effectiveness evidence was taken from the period 1990 to Health service resource use and costs were taken from the period 1998 to The price year was not reported. Source of effectiveness data The effectiveness data were derived from published studies. Modelling A decision-analysis model was created to perform the cost comparison of the two procedures. A decision tree was constructed over a 30-day time horizon. The objective of the model was to evaluate cost outcomes only. The authors justified this approach, stating that the time horizon for an appendectomy and recovery is usually no longer than one month and it would not be clinically meaningful to measure the effectiveness in the model. Some effectiveness data were incorporated in the model, but as a necessity to derive the total costs. Outcomes assessed in the review The outcomes included in the model were the probabilities of conversion to open appendectomy, wound infection, intraabdominal abscess, and the days to return to normal activity. Study designs and other criteria for inclusion in the review A review of the literature that compared laparoscopic and open appendectomy was performed. In particular, this Page: 1 / 6

2 included randomised controlled trials, meta-analyses, and studies in which the Medicare database was used for the cost analysis. Sources searched to identify primary studies MEDLINE was searched for all articles dating from 1990 to 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 The baseline values were taken from two meta-analyses (Golub et al. 1998, and Chung et al. 1999, see 'Other Publications of Related Interest' below for bibliographic details). The ranges were derived from the studies that comprised these two meta-analyses and included 11 additional primary studies. Methods of combining primary studies Investigation of differences between primary studies Results of the review The point estimates of the parameters used in the model were: 0.10 for open conversion (range: 0-27); 0.03 for wound infection of laparoscopic appendectomy (range: 0-10); 0.07 for wound infection of open appendectomy (range: 0-15); 0.10 for wound infection of conversion (range: 0-23); 0.02 for intra-abdominal abscess of laparoscopic appendectomy (range: 0-24); 0.01 for intra-abdominal abscess of open appendectomy (range: 0-10); and 0.01 for intra-abdominal abscess of conversion (range: 0-10). The days for returning to normal activity were 11 for laparoscopic appendectomy (range: 9-20) and 18 for open appendectomy (range: 14-32). Methods used to derive estimates of effectiveness Some authors' assumptions were used to supplement the published literature. Estimates of effectiveness and key assumptions Page: 2 / 6

3 It was assumed that all modelled outcomes occurred in the first 30 days after the procedure. In addition, the authors assumed that the only possible outcomes after the procedure were uneventful recovery, the development of wound infection, or the development of an intra-abdominal abscess. Measure of benefits used in the economic analysis No summary measure of benefit was used in the economic evaluation because the authors stated that the 30-day time horizon would not be clinically meaningful in terms of measuring the effectiveness. As such, the only outcomes considered further were cost outcomes. Direct costs The direct hospital costs included were physician services, room, and board, supplies, operating room expenses and inpatient medications. These were obtained from published literature (Long et al. 2001, see 'Other Publications of Related Interest' below for bibliographic details). The costs associated with complications were derived from published literature (Messick et al see 'Other Publications of Related Interest' below for bibliographic details) and approximated using Medicare costs. Discounting was not carried out as the costs were incurred during less than 2 years. The quantities and the costs were not analysed separately. The estimation of the quantities and costs was derived using modelling. The price year was not reported. Statistical analysis of costs No statistical analysis of the costs was reported. Indirect Costs The indirect costs were included for the societal perspective. These were the costs associated with lost productivity during hospitalisation and subsequent recovery. The indirect costs were valued using standard methods on the basis of gender- and age-specific average hourly wage rates from the Bureau of Labour Statistics Current Population Survey. Discounting was not carried out as the costs were incurred during less than 2 years. The quantities and the costs were not analysed separately. The estimation of the quantities and costs was derived using modelling. The price year was not reported. Currency US dollars ($). Sensitivity analysis A sensitivity analysis was carried out to investigate variability in the data. One-way sensitivity analyses were performed for each probability in the model, and the threshold value at which the optimal strategy changed was identified. The ranges were derived from published literature. Estimated benefits used in the economic analysis Not relevant. Cost results From the hospital perspective, the baseline analysis showed that an open appendectomy cost $5,171 and a laparoscopic appendectomy $6,118. From the societal perspective, the baseline analysis showed that an open appendectomy cost $12,055 and a laparoscopic appendectomy $10,400. Page: 3 / 6

4 From the hospital perspective, laparoscopic appendectomy would become the optimal strategy only if the wound infection rate for open appendectomy exceeded 23%, or if the intra-abdominal abscess rate exceeded 13%. In both cases, the authors stated that this was highly unlikely to occur in most centres. From the societal perspective, open appendectomy would become the optimal strategy only if more than 29% of laparoscopic appendectomies required open conversion, or if the intra-abdominal abscess rate exceeded 17%. Both of these threshold values were outside of the usual range. Also, from this perspective, the threshold analysis showed that if it takes longer than 14 days for a patient to return to normal activity after laparoscopic appendectomy, open appendectomy was preferred. Synthesis of costs and benefits Not relevant. Authors' conclusions The decision analysis model helped to elucidate the factors that contribute in the determination of the optimal economic strategy for appendectomy. The open appendectomy is the optimal strategy from the hospital perspective, while laparoscopic appendectomy is the optimal strategy from the societal perspective. CRD COMMENTARY - Selection of comparators The authors justified their choice of the comparators on the grounds of the discordance found among studies evaluating the cost of both strategies. You should judge whether these strategies are relevant in your setting, or whether other comparators could also be relevant. Validity of estimate of measure of effectiveness The effectiveness evidence was incorporated to derive strategies (total expected costs), and no aggregate measure of effectiveness was used by the authors. The effectiveness evidence was mainly derived from two meta-analyses (Golub et al and Chung et al. 1999), as well as randomised clinical trials. These are adequate sources from which to estimate effectiveness. It was unclear if a systematic review of the literature was undertaken. Although a more ad-hoc review approach is common practice with models, it does not always ensure that the best data available are used in the model. The authors used data from the available studies selectively. It was not possible to be certain that all the relevant literature was identified, although it is certain that meta-analyses were used to derive the effectiveness of both procedures. The estimates of effectiveness were derived credibly from the studies identified. The authors used data from published sources and their own assumptions. The authors justified their assumptions with reference to the medical literature. The estimates were investigated in sensitivity analyses using ranges from the literature. Validity of estimate of measure of benefit The authors did not derive a summary measure of health benefit. The reader is referred to the comments in the 'Validity of estimate of measure of effectiveness' field (above). Validity of estimate of costs The authors reported that the costs were estimated from both a hospital perspective and a societal perspective. Although the indirect costs were appropriately included for the societal perspective, it was unclear whether all the other direct costs were included and some might have been omitted from the analysis. However, these omissions were unlikely to have affected the authors' conclusions as the costs were common to both strategies. The resource use quantities and prices were taken from published sources but were not reported separately. Sensitivity analyses of the costs were not conducted. Discounting was not carried out, but this was appropriate as the time horizon was less than 2 years. The costs were not reflated and the price year was not reported, which will hinder any future reflation exercise. Page: 4 / 6

5 Other issues The authors' conclusions reflected the scope of their analysis. The authors did not make appropriate comparisons of their findings with those from other studies. They also did not explicitly address the issue of the generalisability of the results. However, they did recognise that they did not build into the model the ability to account for differences in body habitus, gender, or co-morbidities. In addition, they also stated that the study was subject to other limitations common to all decision analysis models in that it combined data from numerous sources and, specifically, that they chose to construct a more general model that did not look at differences in outcomes based on whether the appendix was perforated or gangrenous. These important clinical parameters have been shown, in some studies, to alter procedural outcomes. Implications of the study Although from the hospital perspective open appendectomy appears to be the optimal strategy, laparoscopic appendectomy seems to be optimal from the societal perspective. Decision analyses can help in the understanding of a wide range of clinical scenarios and patient characteristics, and can help detect contributing factors in the determination of the optimal strategy for appendectomy. Source of funding None stated. Bibliographic details Moore D E, Speroff T, Grogan E, Poulose B, Holzman M D. Cost perspectives of laparoscopic and open appendectomy. Surgical Endoscopy 2005; 19(3): PubMedID DOI /s Other publications of related interest Golub R, Siddiqui F, Pohl D. Laparoscopic versus open appendectomy: a meta-analysis. J Am Coll Surg 1998;186: Chung RS, Rowland DY, Li P, et al. A meta-analysis of randomised controlled trials of laparoscopic versus conventional appendectomy. Am J Surg 1999;177: Long KH, Bannon MP, Zietlow SP, et al. A prospective randomised comparison of laparoscopic appendectomy with open appendectomy: clinical and economic analyses. Surgery 2001;129: Messick CR, Mamdani M, McNichol IR, et al. Pharmacoeconomic analysis of ampicillin-sulbactan versus cefoxitin in the treatment of intra-abdominal infection. Pharmacotherapy 1998;18: Indexing Status Subject indexing assigned by NLM MeSH Appendectomy /economics /methods; Costs and Cost Analysis; Decision Support Techniques; Humans; Laparoscopy /economics AccessionNumber Page: 5 / 6

6 Powered by TCPDF ( Date bibliographic record published 30/04/2006 Date abstract record published 30/04/2006 Page: 6 / 6