|
Cost-effectiveness of a single colonoscopy in screening for colorectal cancer |
Sonnenberg A, Delco F |
|
|
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 single or repeated colonoscopy for the screening of colorectal cancer (CRC). Single colonoscopy was performed at 65 years of age, while repeated colonoscopy was performed every 10 years starting at the age of 50.
Economic study type Cost-effectiveness analysis.
Study population The study population was the general population in the USA.
Setting The setting was the community. The economic study was carried out in the USA.
Dates to which data relate The effectiveness and resource use data were derived from studies published between 1982 and 1998. The price year was 1998.
Source of effectiveness data The effectiveness evidence was derived from a review of published studies.
Modelling A Markov model was used to assess the lifetime costs and life-years gained with the two screening strategies in a hypothetical cohort of 100,000 individuals. Each cycle of the model lasted one year. The health states included in the model were colonoscopy, CRC, polypectomy, post-colonoscopy status, non-compliance and death. Compliance was assumed to be 100% in the base model.
Outcomes assessed in the review The primary health outcomes estimated from the published studies were:
the yearly incidence of adenomas,
the screening interval for colonoscopy,
the surveillance interval after polypectomy,
the compliance rate with initial colonoscopy and repeated colonoscopy,
the efficacy of colonoscopy in CRC prevention,
the bleeding rate after colonoscopy or polypectomy,
the perforation rate after colonoscopy, sigmoidoscopy or polypectomy, and
mortality from CRC.
Study designs and other criteria for inclusion in the review The inclusion and exclusion criteria were not specified. No other details of the primary studies were provided. However, the authors reported that one of the primary studies was a multi-centre trial. Some of the other studies were official statistics.
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 The effectiveness evidence was obtained from eight primary studies.
Methods of combining primary studies The effectiveness estimates were combined using narrative methods.
Investigation of differences between primary studies Results of the review The ranges for sensitivity analyses are shown in brackets.
The yearly incidence of adenomas was 1% (range: 0 - 6).
The screening interval for colonoscopy was 10 years (range: 3 - 10).
The surveillance interval after polypectomy was 3 years (range: 1 - 5).
The compliance rate was 100% (45% point estimate) with initial colonoscopy and 100% (80% point estimate) with repeated colonoscopy.
The efficacy of colonoscopy in CRC prevention was 75% (range: 50 - 75).
The bleeding rate was 0.15% after colonoscopy and 2% after polypectomy.
The perforation rate was 0.2% after colonoscopy, 0.38% after polypectomy and 0.01% after sigmoidoscopy.
The mortality from CRC was 40%.
Measure of benefits used in the economic analysis The benefit measure used in the economic analysis was the life-year saved with the two screening strategies, compared with the no-screening option. The life-years were estimated using modelling and a 3% discount rate was applied. The proportion of CRC cases prevented with the two screening strategies over no screening was also reported.
Direct costs A 3% discount rate was applied as the lifetime costs were assessed. The unit costs were not reported separately from the quantities of resources. The cost items included in the economic evaluation were colonoscopy, polypectomy, bleeding, perforation and medical care for CRC. The costs also included the possibility of hospitalisation for bleeding or perforation after endoscopy with or without polypectomy. However, the cost components were not reported. The costs of CRC care were estimated using the most up-to-date data available. The cost/resource boundary adopted was that of the third-party payer, as the costs were estimated using Medicare reimbursement rates. The price year was 1998.
Statistical analysis of costs The costs were treated deterministically in the base-case.
Indirect Costs The indirect costs were not included in the analysis.
Sensitivity analysis Several one-way sensitivity analyses were conducted to address the issue of variability in the data used in the decision model. The compliance rates, efficacy of colonoscopy, costs and screening age were varied within reasonable ranges, which were determined from the literature.
Estimated benefits used in the economic analysis The proportion of CRC cases prevented over no screening was 23% with single colonoscopy and 75% with repeated colonoscopy.
The life-years saved over no screening were 2,604 with single colonoscopy and 7,952 with repeated colonoscopy.
Cost results The costs of colonoscopy were $41,091,209 with single colonoscopy and $189,667,598 with repeated colonoscopy.
The costs of care for CRC were $136,452,922 with no screening, $103,124,901 with single colonoscopy, and $34,113,230 with repeated colonoscopy.
The overall costs in the cohort of patients were $136,452,922 with no screening, $144,216,110 with single colonoscopy, and $223,780,828 with repeated colonoscopy.
Synthesis of costs and benefits An incremental cost-effectiveness analysis was conducted to combine the costs and benefits of the screening strategies.
The incremental cost per life-year saved over no screening was $2,981 with single colonoscopy and $10,983 with repeated colonoscopy.
The incremental cost per life-year saved of repeated colonoscopy over single colonoscopy was $14,878.
Any reduction in compliance rates affected the cost-effectiveness ratio of repeated colonoscopy. The cost-effectiveness of both strategies was reduced by a lower efficacy of colonoscopy in preventing CRC.
The estimated cost-effectiveness ratios were also sensitive to variations in the costs. In terms of the impact of age on single colonoscopy when compared with no screening, beyond the age of 70 years the screening strategy was cost-saving. This means that the costs spent on screening were outweighed by the costs saved by less cancer care.
Authors' conclusions A single colonoscopy performed at the age of 65 years was a cost-effective screening strategy for colorectal cancer (CRC) in the general population. However, repeated colonoscopy every 10 years, starting at the age of 50, saved considerably more life-years at an extra incremental cost of $14,878 over single colonoscopy.
CRD COMMENTARY - Selection of comparators The authors reported the rationale for the choice of the comparators, which appears to have been justified. While colonoscopy had already been compared with other screening strategies, such as flexible sigmoidoscopy and annual faecal occult blood tests, no comparison between repeated and single colonoscopy had been published. You should decide whether they represent widely used screening programmes in your own setting.
Validity of estimate of measure of effectiveness The analysis of effectiveness used data derived from published studies. However, no formal systematic review of the literature was undertaken. The authors did not state the inclusion or exclusion criteria used to judge the studies, and details of the study designs were unclear. The effectiveness estimates were combined using narrative methods. It was not stated whether the authors took into account any differences between the primary studies.
Validity of estimate of measure of benefit The benefit measure in the economic analysis was the life-years saved. These were appropriately derived using modelling and were discounted at an appropriate rate. The authors stated that a potential drawback of the decision model was the fact that it did not consider the presence of other competing medical risks, such as diabetes and coronary artery disease, in those patients who underwent screening. If individuals were more likely to die from other diseases they would gain less life-years from any screening strategy. The use of life-years permits the benefits of this particular screening to be compared with those of other interventions funded in the health care system.
Validity of estimate of costs The perspective adopted in the analysis was clearly stated. It appears that all the relevant cost components have been included in the study. The costs were appropriately discounted and the price year was reported, thus facilitating reflation exercises to other settings. However, a detailed breakdown of the costs was not given and the unit costs were not reported separately from the resource quantities. Although the costs were treated deterministically in the base-case, sensitivity analyses were conducted on the cost estimates used in the decision model. The costs were derived using actual data, which reflected reimbursement rates.
Other issues The authors compared their findings with those from other studies. The issue of the generalisability of the study results to other settings was not addressed, but several sensitivity analyses were conducted. The study referred to the general population and this was reflected in the conclusions of the analysis.
Implications of the study The main implication of the analysis is that repeated colonoscopy every 10 years represents a medically appealing strategy, but single screening at the age of 65 years is the most cost-effective screening option. However, it should be noted that these conclusions were sensitive to factors such as the compliance rate and cost of the strategies.
Bibliographic details Sonnenberg A, Delco F. Cost-effectiveness of a single colonoscopy in screening for colorectal cancer. Archives of Internal Medicine 2002; 162: 163-168 Indexing Status Subject indexing assigned by NLM MeSH Aged; Colonoscopy /economics; Colorectal Neoplasms /diagnosis /economics; Cost-Benefit Analysis; Decision Support Techniques; Humans; Life Tables; Markov Chains; Mass Screening /economics; Middle Aged AccessionNumber 22002008029 Date bibliographic record published 31/05/2003 Date abstract record published 31/05/2003 |
|
|
|