Economic Models of Colorectal Cancer Screening in Average-Risk Adults Workshop Summary (2005) / Chapter Skim
Currently Skimming:
Appendix I Cost-Effectiveness Analyses of Colorectal Cancer Screening: Results from a Pre-conference Modeling Exercise--Michael Pignone, M.D.,
Appendix I Cost-Effectiveness Analyses of Colorectal Cancer Screening: Results from a Pre-conference Modeling Exercise--Michael Pignone, M.D.,
Pages 118-153
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 118... ...
Appendix I Cost-Effectiveness Analyses of Colorectal Cancer Screening: Results from a Pre-conference Modeling Exercise Michael Pignone, M.D., M.P.H. SLIDE 1 SLIDE 1 NOTES: I would like to thank the following people for their work and advice on this exercise or on a previous review conducted for the US Preventive Services Task Force: Judy Wagner, Louise Russell, Martin Brown, Somnath Saha, Jeanne Mandelblatt, Tom Hoerger, Steve Teutsch, and all of the modelers who participated in this exercise.
|
From page 119... ...
The last motivation, however, is less important than the first two. The second objective is to use insights from this exercise to better inform future modeling and direct future CRC research efforts.
|
From page 120... ...
Also, unlike many other areas, there are several recent high-quality published costeffectiveness analyses which reached different conclusions about the relative merits of alternative screening strategies. That fact provides an interesting opportunity, because it offers us a chance to explore how that variation might arise, and whether the variation is there for good reasons, or whether we should try to reduce the variation through standardization of methods and assumptions.
|
From page 121... ...
All seven found that any of the main screening strategies for colorectal cancer were cost-effective compared with no screenings. The cost-effectiveness of any screening strategy compared with doing nothing was generally below $30,000 per year of life added across all models.
|
From page 122... ...
The prototype radiological screening test was defined to have characteristics somewhere in between barium enema, which is relatively inexpensive, and virtual colonoscopy, which is more sensitive but more expensive.
|
From page 123... ...
APPENDIX I 123 SLIDE 6 SLIDE 6 NOTES: We then specified standardized values for inputs in the four categories listed above. The modelers were asked to analyze each of the six strategies 10 times, with each run involving a different combination of original or standardized parameter values.
|
From page 124... ...
Strongly dominated strategies were eliminated. Of the remaining strategies, we identified those that were weakly dominated -- they were both less effective and their costs per year of life added were higher than at least one other strategy.
|
From page 125... ...
APPENDIX I 125 SLIDE 8 SLIDE 8 NOTES: This and the next 5 slides review the standardized assumptions in each general area. Here are some basic assumptions that were common to all runs and all strategies.
|
From page 126... ...
126 ECONOMIC MODELS OF COLORECTAL CANCER SCREENING SLIDE 9 SLIDE 9 NOTES: No notes.
|
From page 127... ...
APPENDIX I 127 SLIDE 10 SLIDE 10 NOTES: No notes.
|
From page 128... ...
128 ECONOMIC MODELS OF COLORECTAL CANCER SCREENING SLIDE 11 SLIDE 11 NOTES: Note that we did not model more complex assumptions regarding complications, such as the possibility of bleeding (short of perforation) with colonoscopy, or other complications, such as a patient who is falls and breaks a bone after colonoscopy.
|
From page 129... ...
All patients with positive radiology test would receive a follow-up colonoscopy All patients with a polyp found on colonoscopy screening would have the lesion removed as part of that procedure. All patients with adenomas found on screening and removed in screening or followup would be entered into a surveillance program requiring a full colonoscopy every 5 years until death or until the patient reaches age 80.
|
From page 130... ...
130 ECONOMIC MODELS OF COLORECTAL CANCER SCREENING SLIDE 13 SLIDE 13 NOTES: When we standardized on assumptions about compliance, we asked modelers to assume that all individuals would be fully compliant with all screening, follow-up and surveillance tests. That assumption is a poor description of reality, but it provided a level playing field for all procedures.
|
From page 131... ...
were set to the standardized values we specified. "O' means that the parameters in a specific run and input group (for example, in run number 3 and the "Cost" assumptions)
|
From page 132... ...
132 ECONOMIC MODELS OF COLORECTAL CANCER SCREENING SLIDE 15 SLIDE 15 NOTES: Run 6 standardizes across all parameter groups. We call that the fully standardized run.
|
From page 133... ...
Within each screening test, there is fairly substantial variation under the original assumptions about the costs of screening.
|
From page 134... ...
134 ECONOMIC MODELS OF COLORECTAL CANCER SCREENING SLIDE 17 SLIDE 17 NOTES: This chart shows for the original assumptions -- the years of life lived in a population of 100,000 50-year old individuals. Here, too, there is a substantial variation between the different models in terms of the number of years of life that would be generated through running the model under each of the different modelers' assumptions.
|
From page 135... ...
, the same pattern is replicated across the models. Substantial differences exist between models.
|
From page 136... ...
. Substantial differences in cost persist across models for each of the different screening strategies.
|
From page 137... ...
A quick scan of these results shows that almost all of the strategies have costeffectiveness ratios of less than $30,000, regardless of the model used. The costeffectiveness ratios tend to vary between $10,000 and $30,000 both across screening strategies and across models.
|
From page 138... ...
The current slide shows for the standardized assumptions (Run 6) -- the lifetime cost of screening, follow-up, surveillance and treatment of CRC in millions of dollars.
|
From page 139... ...
These differences across models may reflect different assumptions about the natural history of CRC. Note that neither natural history nor model structure have been standardized.
|
From page 140... ...
140 ECONOMIC MODELS OF COLORECTAL CANCER SCREENING SLIDE 23 SLIDE 23 NOTES: This slide shows extra lifetime costs compared with the no-screening strategy, under the standardized assumptions (Run 6)
|
From page 141... ...
. Variation across models is now somewhat reduced, probably because some of the differences in assumptions about natural history wash out when the metric is years of life added compared with no screening.
|
From page 142... ...
142 ECONOMIC MODELS OF COLORECTAL CANCER SCREENING SLIDE 25 SLIDE 25 NOTES: In this chart and the next, the same results are grouped by model instead of by strategy. You can see that there is some variation in terms of life years saved within each model by the different strategies, suggesting that the strategies have different levels of effectiveness.
|
From page 143... ...
The relative costs across strategies tend to follow pretty much the same pattern across the different models.
|
From page 144... ...
The results here vary from about $6,000 per life-year saved to about $25,000 per life-year saved. It appears from visual inspection that there is slightly less overall variation than we had under the original assumptions.
|
From page 145... ...
Recall that the incremental cost-effectiveness ratio (ICER) is calculated by eliminating all strongly and weakly dominated strategies and then sorting the remaining strategies in ascending order according to years of life added compared with no screening.
|
From page 146... ...
For example, flexible sigmoidoscopy every five years is dominated in all but the Miscan model. In four of the five models, colonoscopy is either weakly or strongly dominated by other tests.
|
From page 147... ...
When they were not, they had a high incremental cost-effectiveness ratio. Finally, annual FOBT plus flexible sigmoidoscopy under these particular standardized assumptions produced additional life years at a fairly high additional cost.
|
From page 148... ...
So, for example, the Harvard model predicts that annual FOBT is the most effective strategy among all strategies whose ICER is $20,000 or less. There is a great deal of variation across models in which strategy is preferred at any cost-effectiveness threshold.
|
From page 149... ...
The most effective strategy at any different threshold is the same. In fact, the only difference is the threshold level at which the FOBT with FSIG overtakes FOBT alone as the preferred strategy.
|
From page 150... ...
The effects of standardizing assumptions might differ with other sets of screening strategies. It might be useful, for example, to do an exercise that includes more complex screening strategies such as one that begins with one screening test and transitions over time to another as individuals age.
|
From page 151... ...
APPENDIX I 151 SLIDE 34 SLIDE 34 NOTES: In this chart and the next, the same results are grouped by model instead of by strategy. You can see that there is some variation in terms of life years saved within each model by the different strategies, suggesting that the strategies have different levels of effectiveness.
|
From page 152... ...
We also need additional research in modeling compliance. I believe we are still missing some of the key input parameters that would help us to more effectively and accurately model what actually happens in terms of compliance.
|
From page 153... ...
Preventive Services Task Force. Ann Intern Med.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.