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Stephen T. Parente, Ph.D. Carlson School of Management, Department of Finance

University of Minnesota Medical Technology Evaluation and Market Research Department of Healthcare Management Course: MILI/PUBH 6589 Spring Semester, 2013. Stephen T. Parente, Ph.D. Carlson School of Management, Department of Finance. Class Overview Measuring Effectiveness. Health state 101

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Stephen T. Parente, Ph.D. Carlson School of Management, Department of Finance

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  1. University of MinnesotaMedical Technology Evaluation and Market Research Department of Healthcare ManagementCourse: MILI/PUBH 6589Spring Semester, 2013 Stephen T. Parente, Ph.D. Carlson School of Management, Department of Finance

  2. Class OverviewMeasuring Effectiveness • Health state 101 • Specifying clinical outcomes • Measuring outcomes • Use of decision trees in effectiveness analysis

  3. Terminology: “Health State” “The health of an individual at any particular point in time.” [Gold et al 1996]

  4. When Considering an Assessment of Health: Two areas of concern • Length of life • mortality rates • life expectancy • Quality of life • ability/disability • independence • other aspects of health & well-being

  5. We need measurement scales for • quality of life • combination of quality & length What do we mean by “measurement” of outcomes?

  6. Measurement • Process of setting up a correspondence between • Some set of things (here health states) • Numbers • So that qualitative relations among the things (such as “better than”) are reflected by the quantitative numerical relationships

  7. Some differences in scales matter; some don’t Averages on 3 different scales: Pain ratings from 6 people: A,B,B,B,C,D 1.33 23.33 3.92

  8. Goal of health outcome measurement • Assign scales so that when we do arithmetic, the averages work out the way we think they should. • Use common vales to permit apples to apples comparison.

  9. How about a single measure that combines morbidity & mortality? • Simple idea:Weight each year of life with a measure of degree of good/poor health. Add up the weighted life years.

  10. Excellent Overall Health Quality Dead now death additional years of life QALYs = area under this curve QALE = average number of QALYs experienced by a cohort of the same starting age and quality of life = best estimate of future health-adjusted life years for random member of the cohort “Life Path” = the general health outcome

  11. Mathematical Assumption to make QALY tractable: • “Q” weighting is separable from duration of the health state it represents and other health states in the life path • simplifies data collection immensely! • Life expectancy obtained from medical data • combined mathematically instead of by judgment

  12. Issues ... • What aspects of “health” are normally covered in a health-related quality of life (HRQOL) measure? • How is a health classification system operationalized? • How are numbers (weights) assigned to health states?

  13. Illustrate with several different measures • QWB Quality of Well-being scale • HUI Health Utility Index • YHL measure in Years of Healthy Life • EQ-5D EuroQol health status measure • SF-36 Questionnaire-based health profile

  14. Excellent Overall HRQOL Dead now death additional years of life Continuum of health state weights

  15. Health Status Measurement System Excellent Description system covering all health states Overall Health Death Function corresponding states to scale values so arithmetic “works” Numerical scale

  16. “The health of an individual at any particular point in time.” • Things “health” might include ... • Functional abilities? Which ones? • Pain? • Other? “Dimensions” of Health

  17. Health Perceptions Social Function Soc. relations role function intimacy communication Impairment sensory function/loss symptoms Psychological Funct. Cognitive emotional mood/feelings Physical Function mobility physical activity self-care Typical Concepts & Domains

  18. A Hierarchy of Health Dimensions

  19. Health states are multidimensional • Measure as vector • one number for each dimension • Create one summary number

  20. Example • State 1 • intermittent moderate pain • no mobility limitations • able to do normal socio-occup. functions • State 2 • continuous mild pain • mobility limitation • some occupational restrictions

  21. Physical Function Profile (“vector”) representation 1. Decide what dimensions 2. Develop scales for each dimension 3. Develop process for locating patients on each dimension A B Social Function Pain PFSFP A =(70,30,50) B =(55,60,90)

  22. Perfect health 100 Single number (“scalar”) representation: 1. Same steps as for a profile +2. Develop process for aggregating the attributes into one summary number. OR Just do direct aggregate scaling 65 State B State A 45 dead 0

  23. Functional ability Example classification scheme: YHL

  24. Example classification scheme: YHL 5 levels of self-rating x 6 levels of function = 30 health states An intermediate health state Best Worst

  25. Scaling the Health States: An intermediate health state Best Worst Dead 1.0 ? ? 0.0

  26. Weights for YHL Functional ability Note: “dead” = 0.00

  27. Definitions ….. • HALYs: health-adjusted life years using a health status measure for health weights • QALYs: quality-adjusted life years… a type of HALY computed using a HRQOL measure for health weights.

  28. Disease Specific General Health non-preference Many! e.g. joint counts total cholesterol physical measures -- SIP, Rand GHS, COOP, MOS short forms EVGFP Many! rating scales preference based QWB, HUI, EQ-5D, YHL? indexed ? patient’s own prefs. ad hoc ad hoc

  29. Disease-specific instruments • Very specific to intended effects of treatments • Can be sensitive to small changes in disease activity/status • Clinicians can link to specific actions

  30. But disease-specific measures may miss things • Many treatments have unintended effects (arthritis & hearing) • Many people (especially when older) have multiple health conditions (median number is 3) ...

  31. Why an interest in measures of General Health?(aka “generic measures”) • Allows many comparisons: • across diseases • in people with multiple conditions • across studies • Needed for cost-effectiveness studies

  32. Medical Outcomes Study -- “short forms” • Derived from Rand General Health Survey • Originally 250+ questions • Published short forms that are in use: • SF-12 • SF-20 • SF-36

  33. SF-36 • 8 components, scaled worst=0 to best=100 • Physical functioning • Role function (from physical limitation) • Pain • General Health Perception Mental health • Vitality • Social functioning • Role function (from emotional limitation) • Mental health

  34. New Scaling for SF-36 & SF-12 • PCS : physical component scale • MCS: mental component scale

  35. Two web sites for SF-36 • http://www.sf-36.org/demos/SF-36.html • http://www.sf-36.org/images/maruishslide1.jpg

  36. Decision Tree Overview: Movement Across Health States Over Time

  37. What’s Next? • Break • Technology Evaluation Roundtable • Projects

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