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Outcomes after detection of metastatic carcinoma of the colon and rectum in a national hospital system |
Wade T P, Virgo K S, Li M J, Callander P W, Longo W E, Johnson F 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 Technologies for detecting and treating metastatic carcinoma of the colon and rectum were studied. The diagnostic technologies considered (either in isolation or in combination with one or more of the other technologies) were serum carcinoembryonic antigen analysis, computed tomography, liver biopsy, sigmoidoscopy and colonoscopy. The surgical technologies for treating the disease were colectomy and hepatic resection.
Economic study type Cost-effectiveness analysis.
Study population The study population comprised 12,150 patients with a diagnosis of carcinoma of the colon and rectum, of whom 6,607 were listed with hepatic metastases.
Setting The large, nationwide hospital system operated by the US Department of Veterans Affairs (DVA) was the setting for the study. The economic study was carried out in the USA.
Dates to which data relate Effectiveness and resource-use data were based on the years 1988 to 1994.1992 prices were used.
Source of effectiveness data The evidence for final outcomes was derived from a single study.
Link between effectiveness and cost data The costing was undertaken retrospectively on the same patient sample as that used in the effectiveness study.
Study sample Of 2,040 patients with ICD-9-CM diagnostic codes indicating metachronous, isolated colorectal hepatic metastases (who had no previous metastases or other current carcinoma site), 887 had either CT scan alone (n=114) or liver biopsy, or both (n=773) as the method of diagnosis but did not undergo resection. This group of 887 unresected patients were compared to the additional 161 patients who underwent hepatic lobar or wedge resections of colorectal metastases and 76 patients who had pulmonary resections. No power calculations were reported.
Study design Retrospective case series conducted in a nationwide hospital system in the United States.
Analysis of effectiveness The analysis of effectiveness was based on intention to treat. Five-year survival was the primary health outcome. (Survival data for those alive at the end of that period were censored). The mean age of patients with isolated hepatic colorectal metastases was 65 years (64 in those who underwent hepatic resection and 66 years in those who did not). The colon was significantly more likely than the rectum to be the site of primary carcinoma in patients who underwent hepatic resection (p<0.001).
Effectiveness results After pulmonary metachronous colorectal metastatectomy, mean patient survival was 38 months with a projected five-year survival rate of 36%, and an operative mortality rate of 3%. After excision of hepatic metastases, mean patient survival was 31 months and the projected five-year survival rate was 26%. The unresected group had a mean survival of 11 months and a projected five-year survival rate of 2%. Mean survival was significantly increased (p<0.001) in patients having hepatic resection compared to all unresected subgroups and in the 222 patients who did not undergo resection and who received inpatient chemotherapy (mean survival, 14 months) compared to the 665 patients who did not (10.5 months, p<0.01).
Clinical conclusions The authors concluded that the results confirmed the conclusions derived from previous studies of the value and safety of hepatic resection for colorectal hepatic metastases. Although resection was applied in only 2.4% of patients who had colorectal metastases, and only 30% survived for five years, resection was again confirmed as the standard therapy.
Measure of benefits used in the economic analysis Lives saved and years of additional life saved were used as the outcome measure in the economic analysis.
Direct costs In spite of the 5-year period analysed, costs were not discounted with the quantities of resource use being analysed separately. Cost data for surveillance strategies were compiled using Medicare-allowed charges. Neither the costs of additional diagnostic examinations beyond the surveillance studies nor the expenses of any therapy were included in the analyses. The authors surveyed members of the Society of Surgical Oncology and the American Society of Colon and Rectal Surgery for their most commonly used schedule of follow-up examinations. The price year was 1992.
Indirect Costs No indirect costs were considered.
Sensitivity analysis No sensitivity analyses were performed.
Estimated benefits used in the economic analysis Of the 237 patients selected for potentially curative resection of their metastases, 70 were projected to be five-year survivors. 161 patients with hepatic resection (gaining 20 months of added life relative to resection) and 76 patients undergoing pulmonary resection (gaining 28 months of added life relative to no resection).
Cost results Five year charges for follow-up of patients with carcinoma of the colon and rectum range from $600 for minimal methods, using only two barium enemas, to $16,000 for an intensive strategy that includes repeated CT scans and colonoscopy. However, the survey of members of the Society of Surgical Oncology and the American Society of Colon and Rectal Surgery revealed that the schedule most often used by these specialists averaged $6,709 per patient. On this basis, the authors present a best estimate of follow-up charges expended on the 10,000 DVA patients as $67 million (for all patients cured by colectomy) plus $23.5 million (for patients who have recurrences after a mean of 21 months), for a total of $90.5 million.
Synthesis of costs and benefits The follow-up cost per five-year survivor is $1.3 million ($90.5 million divided by the 70 projected survivors). The follow-up cost for each year of additional life produced by resection of distant metastases was estimated to be $203,000 ($90.5 million divided by 446; 161 patients times 20 months of added life plus 76 patients times 28 months of added life divided by 12 months per year).
Authors' conclusions The authors concluded that despite these high costs, postoperative surveillance after curative colectomy should not be ended as it would result in 1,344 patients losing 20 to 28 months of added life and 448 patients not being cured. Rather, they suggest that a randomized, prospective trial is required to determine which tests and what regimen can best identify distant metastatic carcinoma of the colon and rectum at an early enough stage and allow the only curative treatment (resection) to be promptly provided to those patients who will benefit.
CRD COMMENTARY - Selection of comparators The reason for the choice of the comparator is clear.
Validity of estimate of measure of benefit Despite their careful data-analysis, the retrospective design used by the investigators is likely to be accompanied by various sources of bias. That is implicitly recognised by the authors in the conclusions.
Validity of estimate of costs Resource quantities were not reported separately from prices and inadequate details of the methods of quantity/cost estimation were given. No discounting was applied to costs.
Other issues The conclusions were justified, given the uncertainty in the data. The issue of the generalisability of the results to other countries was not addressed.
Bibliographic details Wade T P, Virgo K S, Li M J, Callander P W, Longo W E, Johnson F E. Outcomes after detection of metastatic carcinoma of the colon and rectum in a national hospital system. Journal of the American College of Surgeons 1996; 182(4): 353-361 Indexing Status Subject indexing assigned by NLM MeSH Carcinoma /economics /secondary /surgery; Colectomy; Colorectal Neoplasms /economics /pathology /surgery; Hospitals, Veterans; Humans; Liver Neoplasms /secondary; Lung Neoplasms /secondary; Medical Records; Retrospective Studies; Survival Analysis; Treatment Outcome AccessionNumber 21996000522 Date bibliographic record published 31/10/1998 Date abstract record published 31/10/1998 |
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