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Can calcium chemoprevention of adenoma recurrence substitute or serve as an adjunct for colonoscopic surveillance? |
Shaukat A, Parekh M, Lipscomb J, Ladabaum U |
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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. CRD summary This study examined the cost-effectiveness of calcium instead of or in addition to surveillance, in 50-year-old patients immediately after polypectomy, for the prevention of adenoma recurrence and colorectal cancer. The authors concluded that calcium after polypectomy was unlikely to be a reasonable substitute for colonoscopy, but it could be beneficial for patients unwilling or unable to undergo surveillance. On the whole, the methods were valid and, despite limited reporting of the data sources, the authors’ conclusions appear to be robust. Type of economic evaluation Cost-effectiveness analysis Study objective This study examined the cost-effectiveness of calcium as a substitute for or addition to surveillance in 50-year-old patients immediately after polypectomy to prevent adenoma recurrence and colorectal cancer. Interventions The strategies were no intervention; elemental calcium 1,200mg per day from age 50 to 80 years; colonoscopy from age 50 to 80 years, every five years or every three years for large adenomas; and calcium plus colonoscopy. Methods Analytical approach:A Markov model, with a lifetime horizon, was developed to assess the clinical and economic impact of the strategies. The authors stated that the perspective of the third-party payer was taken.
Effectiveness data:The clinical evidence was identified through a search of MEDLINE in March 2006. Various sources of evidence were selected, including the National Polyp Study, chemoprevention trials, and a meta-analysis carried out by the authors of this study. Some assumptions were also required. The key clinical input was the efficacy of calcium in chemoprevention, which was the relative risk of adenoma at three years with calcium compared with without. These data were from randomised controlled trials.
Monetary benefit and utility valuations:Not considered.
Measure of benefit:Life-years (LYs) were the summary benefit measure and they were discounted at 3% per year.
Cost data:The economic analysis included the costs of colonoscopy (with or without lesion removal), calcium, management of endoscopy complications, and treatment of colorectal cancer by stage (localised, regional, or distant). The costs were derived from Medicare fee schedules (including professional fees and procedural reimbursement), health maintenance organisations, and diagnosis-related groups. These data were used in a previous decision analysis and were supplemented with estimates from more recent reports. All costs were in US dollars ($) and the price year was 2006. A 3% annual discount rate was applied.
Analysis of uncertainty:Deterministic sensitivity analyses were carried out on all the model inputs, using plausible ranges of values derived from publications. Results The expected LYs were 18.642 with no intervention, 18.654 with calcium, 18.729 with colonoscopy, and 18.729 with calcium and colonoscopy. The costs were $2,796 with no intervention, $3,392 with calcium, $4,579 with colonoscopy, and $5,426 with calcium and colonoscopy.
Compared with no intervention, the incremental cost-effectiveness ratio (ICER) was $49,900 with calcium, $20,600 with colonoscopy, and $30,300 with both. Compared with calcium, the ICER was $15,900 with colonoscopy and $27,200 with calcium and colonoscopy. The ICER of calcium and colonoscopy over colonoscopy was $3,090,000.
The sensitivity analysis showed that the efficacy and cost of calcium were the most influential inputs, but colonoscopy remained preferred, over plausible ranges of values. Authors' conclusions The authors concluded that calcium after polypectomy was unlikely to be a reasonable substitute for surveillance by colonoscopy, but it could be limited to those patients unwilling or unable to undergo colonoscopy. CRD commentary Interventions:The selection of the comparators appears to have been appropriate as surveillance was the usual approach and calcium was the proposed strategy. These are likely to be valid comparators in most settings.
Effectiveness/benefits:The selection of data sources was by a literature review, which should ensure the identification of relevant clinical inputs. More information on the methods, conduct, and results of the review would have been useful. The data were mainly from clinical trials and meta-analyses, which should be valid sources, but their details were not fully reported. The authors made some assumptions, which were conservative against calcium, such as the exclusion of other benefits (e.g. prevention of fractures). The benefit measure was appropriate given the impact of colorectal cancer on survival. LYs are also comparable with the benefits of other health care interventions.
Costs:The data sources and categories of costs appear to have been consistent with the viewpoint. Most of the costs were presented as category totals and were not broken down in individual items. This limits the transparency of the analysis, but is common when cancer costs are estimated. These estimates were used in another decision analysis and limited details on their derivation were given in this study. The price year and the use of discounting were clearly reported. The key cost estimates were varied in the sensitivity analysis.
Analysis and results:The analytic approach was valid and an incremental analysis was appropriate. The findings were extensively presented and discussed. The issue of uncertainty was partially investigated in a deterministic analysis and the results were clearly reported. A multivariate analysis would have been useful. An important assumption in the model was the full adherence to colonoscopy, whilst in clinical practice adherence is relatively low. This might have overestimated the benefits for colonoscopy.
Concluding remarks:On the whole, the methods were valid and, despite limited reporting of the data sources, the authors’ conclusions appear to be robust. Funding Supported by the National Institutes of Health, Minneapolis Center for Epidemiological and Clinical Research, and the VA Clinical Research Center of Excellence. Bibliographic details Shaukat A, Parekh M, Lipscomb J, Ladabaum U. Can calcium chemoprevention of adenoma recurrence substitute or serve as an adjunct for colonoscopic surveillance? International Journal of Technology Assessment in Health Care 2009; 25(2): 222-231 Indexing Status Subject indexing assigned by NLM MeSH Adenoma /prevention & Aged; Aged, 80 and over; Calcium /economics /therapeutic use; Colonic Polyps /prevention & Colonoscopy; Colorectal Neoplasms /prevention & Cost-Benefit Analysis; Humans; Markov Chains; Middle Aged; Quality-Adjusted Life Years; control; control; control /surgery AccessionNumber 22009101684 Date bibliographic record published 05/08/2009 Date abstract record published 07/07/2010 |
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