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An analysis of multiple staging management strategies for carcinoma of the esophagus: computed tomography, endoscopic ultrasound, positron emission tomography, and thoracoscopy/laparoscopy |
Wallace M B, Nietert P J, Earle C, Krasna M J, Hawes R H, Hoffman B J, Reed C E |
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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 The use of the following technologies for the detection of locally advanced or metastatic oesophageal cancer:
computed tomography (CT);
CT plus endoscopic ultrasound-fine-needle aspiration biopsy (CT+EUS-FNA);
CT plus thoracoscopy and laparoscopy (CT+TL);
CT+EUS-FNA+TL;
CT plus positron emission tomography plus EUS-FNA (CT+PET+EUS-FNA);
PET+EUS-FNA.
The tests were performed sequentially and, in the case of finding and confirming metastases, no further test was performed. Oesophageal resection and follow-up treatment was given to those patients for whom local or regional disease was detected. Only palliative care was given to patients for whom distant disease was detected.
Study population The study population was formed by a hypothetical cohort of oesophageal cancer patients from the Medicare-eligible patients (people aged 65 years or older, younger disabled people, or those with end-stage renal disease). Patients who had any prior cancer, who were enrolled in a health maintenance organisation, or whose cancer was detected at death or post-mortem, were excluded.
Setting The setting appears to have been a hospital. The economic study was performed in the USA.
Dates to which data relate The effectiveness data were collected from studies published between 1997 and 2001, and from the opinions of experts. The cost data related to 1 January 1991 to 31 December 1996. The price year was 2000.
Source of effectiveness data The estimates of effectiveness were derived from a review of completed studies and experts' opinions.
Modelling A decision tree was used to compare the cost and effectiveness of the six strategies.
Outcomes assessed in the review The outcomes assessed in the review were:
the sensitivity and specificity of the tests;
the local or regional prevalence and the distant prevalence of patients with oesophageal cancer;
the life expectancies for non-resected oesophageal cancer patients with local, regional or distant disease;
the life expectancies for resected oesophageal cancer patients with local and regional disease;
the probability of death for patients undergoing TL and those undergoing oesophageal resection.
Study designs and other criteria for inclusion in the review 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 At least 8 studies were included in the review. The authors did not report the design of the studies included in the review.
Methods of combining primary studies Investigation of differences between primary studies Results of the review The sensitivity of CT was 0.60 and the specificity was 0.86. The sensitivity of EUS-FNA was 0.93 and the specificity was 1.00. Both the sensitivity and specificity of TL were 1.00. The sensitivity of PET was 0.67 and the specificity was 0.91.
Local or regional disease prevalence was 70%, and distant disease prevalence was 30%.
For patients with local disease, the life expectancies were 3.68 years with resection and 1.30 years without resection. For patients with regional disease, the life expectancies were 1.13 years with resection and 0.70 years without resection. For patients with distant disease who did not undergo resection, the life expectancy was 0.37 years.
Methods used to derive estimates of effectiveness The opinions of experts were used to assess the life expectancy of resected oesophageal cancer patients with distant disease. Also, the surgical mortality related to TL and to oesophageal resection.
Estimates of effectiveness and key assumptions The life expectancy for patients with distant disease who underwent resection was estimated to be 0.42 years.
The surgical mortality related to TL was estimated to be 0.1%, and that associated with oesophageal resection was estimated to be 5%.
Measure of benefits used in the economic analysis Quality-adjusted life-years (QALYs) were used as the health benefit measure. Experts' opinions were employed to obtain the quality of life utilities. Life expectancy was adjusted for quality of life. The values used were 0.70 (unresected patient) and 0.60 (resected patient) for one year of life of a patient with local or regional disease, and 0.50 (unresected patient) and 0.40 (resected patient) for one year of life of a patient with distant disease. The authors did not report whose values were used to assess these utilities, when and how they were valued, or the valuation tool employed to obtain them.
Direct costs The resource quantities and the costs were not reported separately. Although the quantities were not reported, they were collected retrospectively between 1 January 1991 and 31 December 1996. The direct costs included in the analysis appear to have been those of the health service. The categories of costs included were the costs related to the staging procedures, oesophagectomy and postsurgical care, and palliative care. All the costs related to the procedures were obtained from the Medicare reimbursement rates. The costs related to the treatment of patients were derived from the Surveillance, Epidemiology, and End Results (SEER) Medicare linked databases. Some adjustments, which may have been appropriate, were made to take account of the case-mix of patients, age, time and geographic factors. The costs were estimated using actual data, and the authors reported the average costs. The costs were inflated to 2000 prices using the consumer price index. The authors reported that they considered a 0 and a 3% discount rate. Discounting was potentially relevant, as the time horizon considered for the analysis seemed to be until the patients' death (and the life expectancy was longer than 2 years for patients with local disease and resection), but was not conducted.
Statistical analysis of costs No statistical analysis of the costs was reported.
Indirect Costs No indirect costs were reported.
Sensitivity analysis One-way sensitivity analyses were performed to assess the variability in the data. Both the effectiveness and cost estimates were varied. The ranges used for these sensitivity analyses seem to have been appropriate, according to the effectiveness estimators obtained from the review and the experts' opinions.
Estimated benefits used in the economic analysis The average life expectancy for patients under each management strategy was 1.6628 years with CT, 1.6572 years with CT+EUS-FNA, 1.6493 years with CT+TL, 1.6496 with CT+EUS-FNA+TL, 1.6569 with CT+PET+EUS-FNA, and 1.7948 with PET+EUS-FNA.
The average discounted QALYs under each strategy were 0.9630 with CT, 0.9649 with CT+EUS-FNA, 0.9642 with CT+TL, 0.9642 with CT+EUS-FNA+TL, 0.9650 with CT+PET+EUS-FNA, and 1.0336 with PET+EUS-FNA.
The duration of benefits may have been calculated from the initial staging to the patient's death. It is unclear whether the side effects of treatment were considered in the utility values that were applied to the patients' life expectancy.
Cost results The total costs were $42,153 for CT, $40,363 for CT+EUS-FNA, $50,703 for CT+TL, $49,517 for CT+EUS-FNA+TL, $41,929 for CT+PET+EUS-FNA, and $44,521 for PET+EUS-FNA. It was unclear whether these total costs were discounted or not.
Synthesis of costs and benefits As the CT+EUS-FNA strategy was dominant over the CT, CT+TL, CT+EUS-FNA+TL and CT+PET+EUS-FNA strategies (having higher effectiveness at a lower cost), the authors limited the calculation of incremental cost-effectiveness ratios to PET+EUS-FNA (which presented the highest effectiveness) compared to CT+EUS-FNA. The incremental cost-effectiveness ratio was equal to $60,544 per QALY. The authors reported that the sensitivity analyses showed that the results of the study were very robust and changed only under extreme values.
Authors' conclusions The results obtained in the study suggest that oesophageal cancer patients should undergo initial positron emission tomography (PET) staging and, if no metastatic disease is detected, endoscopic ultrasound (EUS). The incremental cost-effectiveness ratio of this strategy was considered by the authors to be in line with other commonly accepted cancer-screening methods. When PET is not available, computed tomography (CT) plus endoscopic fine-needle aspiration biopsy (EUS-FNA) can be used, because it is slightly less effective and less expensive than PET.
CRD COMMENTARY - Selection of comparators Several strategies combining different staging tests were compared with each other. The authors included CT alone as one of the strategies because it was the standard procedure for staging oesophageal cancer in their setting. You should decide if any of the strategies compared in the study are widely used health technologies in your own setting.
Validity of estimate of measure of effectiveness The authors did not state that a systematic review of the literature had been undertaken. The sources searched and the method used to select the data were not reported. It appears that the effectiveness estimates were combined using narrative methods. The impact of differences between the primary studies was not investigated. Some of the effectiveness estimators were derived from experts' opinions. Nevertheless, it was not reported how many experts participated in the effectiveness estimation, how the experts were chosen, or how the experts' opinions were derived. Sensitivity analyses that varied the values of the effectiveness estimators were performed, which increases the validity of the results. On the other hand, the authors acknowledged the limitation of using a decision analytic model to obtain effectiveness estimators, because of the assumptions that have to be made. However, they argued that the assumptions were conservative and the results of the sensitivity analyses showed the robustness of the results.
Validity of estimate of measure of benefit The measure of benefit used in the economic analysis was QALYs, which appears to have been calculated from the initial staging until the patient's death. The QALYs were obtained by applying utility values to the expected life expectancy of oesophageal cancer patients. The utility values were derived from experts' opinions, although the authors did not report the experts participating in the valuation of these utilities, nor the process by which the experts were selected. However, sensitivity analyses that considered the entire range that the utility values could take were performed, and the results demonstrated robustness. The QALYs were discounted, although there is considerable discussion about whether health benefits should be discounted or not. It is unclear whether the costs were also discounted.
Validity of estimate of costs All the categories of costs relevant to the perspective adopted appear to have been included in the analysis. The costs and the quantities were not reported separately. The price year was reported, considering some adjustments. It should be noted that Medicare reimbursements were used as proxies of costs, and these do not reflect true opportunity costs. This limits the generalisability of the results. Discounting appears to have been relevant since the follow-up for some patients was longer than 2 years. However, the authors did not clearly state if they finally discounted the costs or not. As the authors discounted QALYs, but did not seem to discount the costs, it does not appear methodologically correct to discount the benefits but not the costs. If this was the case in this analysis, caution should be taken when interpreting the results since this approach would increase the cost-effectiveness ratios.
Other issues The authors made appropriate comparisons of their findings with those from other studies. The issue of the generalisability of the results was addressed. The authors reported that the results may not be generalisable to other settings or groups of patients (e.g. younger patients, who may have less co-morbidity), as the hypothetical patients considered in the study (from whom the costs were obtained) were enrolled in Medicare and were, therefore (by implication), older than 65 years.
Implications of the study The authors recommend that the findings of this study should be further studied and supported by prospective clinical trials. Moreover, some points in the study were unclear and the study presented some limitations. Therefore, caution should be taken when interpreting the results.
Source of funding Funded in part by a grant from the American Digestive Health Foundation, TAP Pharmaceuticals Outcomes Research Award.
Bibliographic details Wallace M B, Nietert P J, Earle C, Krasna M J, Hawes R H, Hoffman B J, Reed C E. An analysis of multiple staging management strategies for carcinoma of the esophagus: computed tomography, endoscopic ultrasound, positron emission tomography, and thoracoscopy/laparoscopy. Annals of Thoracic Surgery 2002; 74(4): 1026-1032 Other publications of related interest Flamen P, Lerut A, Van Cutsem E, et al. Utility of positron emission tomography for the staging of patients with potentially operable esophageal carcinoma. Journal of Clinical Oncology 2000;18:3202-10.
Kole AC, Plukker JT, Nieweg OE, Vaalburg W. Positron emission tomography for staging of oesophageal and gastroesophageal malignancy. British Journal of Cancer 1998;78:521-7.
Krasna MJ, Reed CE, Nedzwiecki D, et al. CALGB 9380: a prospective trial of the feasibility of thoracoscopy/laparoscopy in staging esophageal cancer. Annals of Thoracic Surgery 2001;71:1073-9.
Reed CE, Mishra G, Sahai AV, Hoffman BJ, Hawes RH. Esophageal cancer staging: improved accuracy by endoscopic ultrasound of celiac lymph nodes. Annals of Thoracic Surgery 1999;67:319-22.
Wright TA, Gray MR, Morris AI, et al. Cost effectiveness of detecting Barrett's Cancer. Gut 1996;39:574-9.
Indexing Status Subject indexing assigned by NLM MeSH Biopsy, Needle; Clinical Trials as Topic; Cost-Benefit Analysis; Costs and Cost Analysis; Decision Support Techniques; Endosonography; Esophageal Neoplasms /diagnosis; Humans; Laparoscopy; Neoplasm Staging /economics /methods; Sensitivity and Specificity; Thoracoscopy; Tomography, Emission-Computed; Tomography, X-Ray Computed AccessionNumber 22002001797 Date bibliographic record published 31/08/2003 Date abstract record published 31/08/2003 |
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