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Review of last week – screening for prostate Ca PSA level (protein released by prostate) initially

Review of last week – screening for prostate Ca PSA level (protein released by prostate) initially assumed to be good screening test and that early detection would save lives lots of money spent before assumptions tested! What features of natural history and rx might reduce

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Review of last week – screening for prostate Ca PSA level (protein released by prostate) initially

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  1. Review of last week – screening for prostate Ca PSA level (protein released by prostate) initially assumed to be good screening test and that early detection would save lives lots of money spent before assumptions tested! What features of natural history and rx might reduce value of early dx compared to other cancers? What were results of large European and US studies? What “lessons” does this suggest?

  2. Week 8. Breast cancer screeing - ELSI “practicum” You have been asked to serve on a committee to make recommendations about who should get mammography screening for breast cancer. You were recommended because, as a BME major, the public health commissioner thinks you would be able to evaluate the issues thoughtfully and be a good representative for the general public. Also, someone said you once took a course on Ethical, Legal, Social Issues …

  3. Your “briefing book” has some bkgd info: Breast cancer incidence ~12% of women over their lifetime increases with age 2nd leading cause of cancer death in women 3% of women die of breast cancer death rate has declined ~30% since 1990 probably from screening + better rx Prognosis curable if confined to the breast at dx How good is mammography as a screening test?

  4. Sensitivity 70-90% (% correct tests in those w/disease) Specificity ~90% (% correct tests in those w/out disease) Of 1000 50-60 yo’s scanned : ~90 called back for further scans ~10 get biopsy, ~2 have cancer What do you make of these numbers? Is this enough info to make a 2x2 table? disease present absent test pos 2 88 90 neg x y 910

  5. In the past, experts have recommended mammography every year, starting at age 40 But younger women have a lot of “false positives”, which -> unnecessary biopsies Commissioner wants you to evaluate if you could delay routine screening till age 50, and perhaps space mammograms to every other year Any questions for the Commissioner about what you are to consider in making your recommendation?

  6. Summary of 8 studies of mamm. screening in 40-50 yo’s NY Sw Canada Sw Sw Sw Sw ? Total What is relative risk for mortality? What do you conclude from this data?

  7. How does risk reduction vary as a function of age?

  8. If 40-49 yo women have the same relative reduction in breast cancer mortality rate (.85) from screening as 50-59 yo women, is it unethical to recommend routine screening only for older women? Should # of women needed to screen to save 1 life (a proxy for cost?) in each group come into this? [which group might this favor?] Should # of life years saved in each group come into this? [which group might this favor?]

  9. Number needed to “invite” to screening to save one life, as a function of age

  10. Potential Harms of Screening Overdiagnosis (proportion of cases that would not have caused symptoms in patient’s lifetime) est. 1-10%, but mostly in older women who would die of something else before breast cancer became symptomatic False positive rate (# mammograms requiring call back or biopsy among those without cancer/ total # pos. mammograms) Unnecessary biopsy rate (% FP’s getting biopsy)

  11. Results and harms by age group Are there significantly increased harms in 40-50 yo’s?

  12. Simulation studies – another way to estimate and compare benefits and harms of different strategies For each strategy, estimate # cases caught early (based on sensitivity, prevalence), # deaths averted (based on data about natural history), if you screen annually vs biennially. How reliable are the estimates?

  13. benefit vs # mammographies done for diff. strategies A=annual screening, B=biennial, #’s = ages screened efficient frontier line Strategies below frontier line provide less benefit for same resource utilization than strategies on the line (in thousands) What might x-axis be a surrogate for?

  14. Another way of looking at how much would be gained +21

  15. How many harms would be avoided by starting later? +23 +430

  16. Do benefits outweigh harms? How do you compare them? Would you like more data to decide? If so, what? ? Quality adjustments for life years saved ? Costs/QALY

  17. Quality of life adjustments – sound reasonable but where do they come from? Ask people to choose between living t years with poor health condition versus x<t years with perfect health. What x makes them indifferent? x/t = QALY adjustment factor Who decides x/t - healthy people or those with condition?

  18. Quality-of-life adjustments for chemotherapy may not have large effects, e.g. …

  19. Cost-effectiveness studies in theory provide way to compare benefits and harms more quantitatively, provide single measure for comparison, e.g. cost/life year saved How different from data considered so far? add costs of treatment could add cost of harms usually discount costs and QALYs by few %/year money not spent till later could earn interest…

  20. Estimate QALYs, and screening and treatments costs for cohorts of women under different screening strategies (until they die). Then calculate extra cost/extra QALY. ICER = incremental cost effectiveness ratio = additional cost/additional QALY

  21. Based on what you’ve learned, how would you vote? A. Leave recommendation as it is: annually, starting at 40 B. Change recommendation to Screen biennially? Start screening at age 50? because harms in younger group exceed benefits? because it is more cost effective? C. Don’t have enough info – let each woman decide (w/her doctor)

  22. USPSTF – considered these issues in fall 2009 What is USPSTF? US Preventive Services Task Force What organization sponsors them? AHRQ – Agency for Health Research & Quality part of HHS Who serves on them? – “experts” MDs, public health officials What might be their biases? Can/do they consider cost-effectiveness? No

  23. What did they recommend? Do you agree?

  24. What is the USPSTF grading system?

  25. USPSTF report and data on which they based their recommendations are on Blackboard Review them, and decide if you feel their recommendations were fair, adequately explained, transparent? Should such recommendations take into account cost-effectiveness? What are consequences of USPSTF-like recommendations?

  26. Next week: guest speaker from FDA, BME major ? worked for Boston Scientific before FDA will talk about how FDA regulates devices and diagnostic tests Homework: look over FDA websites to get a general sense of framework for FDA regulation, e.g. http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/Overview/default.htm Think about: adv./disadv. of FDA regulation Should FDA regulate 23andMe-type tests?

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