Utility Assessment HINF Medical Methodologies Session 4

Objective To review utility assessment techniques and discuss their use determining benefits for interventions To review utility assessment techniques and discuss their use determining benefits for interventions

Reading Roberts M S and Sonnenberg F A (2000) Chapter 3: Utility Assessment under Expected Utility and Rank Dependent Utility Assumptions, in Chapman G B and Sonnenberg F A (eds) Decision Making In Health Care: Theory, Psychology and Applications, Cambridge University Press, USA Roberts M S and Sonnenberg F A (2000) Chapter 3: Utility Assessment under Expected Utility and Rank Dependent Utility Assumptions, in Chapman G B and Sonnenberg F A (eds) Decision Making In Health Care: Theory, Psychology and Applications, Cambridge University Press, USA Goldstein MK and Tsevat J (2007) Chapter 24: Assessing Desirability of Outcomes States, in Interactive Textbook on Clinical Symptom Research, Goldstein MK and Tsevat J (2007) Chapter 24: Assessing Desirability of Outcomes States, in Interactive Textbook on Clinical Symptom Research, Goldstein MK and Tsevat J (2000) Chapter 12: Applying Utility Assessment at the Bedside, in Chapman G B and Sonnenberg F A (eds) Decision Making In Health Care: Theory, Psychology and Applications, Cambridge University Press, USA Goldstein MK and Tsevat J (2000) Chapter 12: Applying Utility Assessment at the Bedside, in Chapman G B and Sonnenberg F A (eds) Decision Making In Health Care: Theory, Psychology and Applications, Cambridge University Press, USA Stiggelbout MA (2000) Chapter 11: Assessing Patient’s Preferences, in Chapman G B and Sonnenberg F A (eds) Decision Making In Health Care: Theory, Psychology and Applications, Cambridge University Press, USA Stiggelbout MA (2000) Chapter 11: Assessing Patient’s Preferences, in Chapman G B and Sonnenberg F A (eds) Decision Making In Health Care: Theory, Psychology and Applications, Cambridge University Press, USA

Evidence Preparation Engine where data is translated into information

Levels of Decision Making Micro level: Patient level decision making Micro level: Patient level decision making Meso level: Organization level decision making Meso level: Organization level decision making Macro level: Society level decision making Macro level: Society level decision making Meta level: Across sectors Meta level: Across sectors

Utility Assessment What is it? In economics, utility is a measure of the relative happiness or satisfaction (gratification) gained by consuming different bundles of goods and services. In economics, utility is a measure of the relative happiness or satisfaction (gratification) gained by consuming different bundles of goods and services. The doctrine of utilitarianism saw the maximization of utility as a moral criterion for the organization of society. According to utilitarians, society should aim to maximize the total utility of individuals, aiming for "the greatest happiness for the greatest number". The doctrine of utilitarianism saw the maximization of utility as a moral criterion for the organization of society. According to utilitarians, society should aim to maximize the total utility of individuals, aiming for "the greatest happiness for the greatest number". Measuring the utility of health states based on preferences of patients Measuring the utility of health states based on preferences of patients Respondents assess the desirability of life in certain states Respondents assess the desirability of life in certain states May be respondents own current health state May be respondents own current health state May be hypothetical state other than their own current health presented to respondents for rating May be hypothetical state other than their own current health presented to respondents for rating

Two models of Direct Utility Assessment The standard gamble: what probability of painless and immediate death she would risk in order to be restored to perfect health or better health than the state under consideration. The standard gamble: what probability of painless and immediate death she would risk in order to be restored to perfect health or better health than the state under consideration. If a subject is willing to take up to a 20 % risk of death in exchange for and 80 % change of perfect health rather than accept the intermediate state for certain, then the utility of the intermediate state is 0.8 If a subject is willing to take up to a 20 % risk of death in exchange for and 80 % change of perfect health rather than accept the intermediate state for certain, then the utility of the intermediate state is 0.8 Time Trade-off: willingness to live shorter but healthier life - equals one minus the maximum proportion of time that the subject is willing to trade off Time Trade-off: willingness to live shorter but healthier life - equals one minus the maximum proportion of time that the subject is willing to trade off Willingness-to-pay: how much one would be willing to pay to avoid an undesirable health state. Willingness-to-pay: how much one would be willing to pay to avoid an undesirable health state. Person Trade-off: how many outcomes of one kind respondents consider equivalent in social value to x outcomes of another kind Person Trade-off: how many outcomes of one kind respondents consider equivalent in social value to x outcomes of another kind Rating scales: e.g. Sickness Impact Profile, Nottingham Health Profile, Older Americans Resources and Services (OARS), SF-36, Quality of Well Being, Visual Analog Scale Rating scales: e.g. Sickness Impact Profile, Nottingham Health Profile, Older Americans Resources and Services (OARS), SF-36, Quality of Well Being, Visual Analog Scale

Two models of preference assessment Health state classification systems (indirect utility assessment): respondent’s health status is ascertained, and then utilities assessed or derived mathematically from a reference group are mapped onto that health state Health state classification systems (indirect utility assessment): respondent’s health status is ascertained, and then utilities assessed or derived mathematically from a reference group are mapped onto that health state Descriptive system – set of attributes and health state is described by indicating appropriate level of functioning Descriptive system – set of attributes and health state is described by indicating appropriate level of functioning Scoring formula - Scoring formula -

Good description of the outcome state must be needed Good description of the outcome state must be needed Patients may have difficulty anticipating their future preferences Patients may have difficulty anticipating their future preferences

Application of Utility Assessment Integration to medical decision making with individual patients Integration to medical decision making with individual patients To calculate QALYs: the QALYs associated with an intervention are estimated as the sum of the future expected life years weighted by the quality of life (expected utility) in each time interval. To calculate QALYs: the QALYs associated with an intervention are estimated as the sum of the future expected life years weighted by the quality of life (expected utility) in each time interval. An intervention can increase the number of QALYs by changing the quality weighting (utility) even if it has no effect or a negative effect on survival; an intervention that improves symptoms can increase the expected utility. An intervention can increase the number of QALYs by changing the quality weighting (utility) even if it has no effect or a negative effect on survival; an intervention that improves symptoms can increase the expected utility. To identify quality weighting; To identify quality weighting; Measure of the impact of the intervention on the distribution of health states Measure of the impact of the intervention on the distribution of health states Assessing the preferences (utilities) for these alternative states of health Assessing the preferences (utilities) for these alternative states of health

QALYs Except for discounting, the long term effect of QALY is a linear function of a one year effect Except for discounting, the long term effect of QALY is a linear function of a one year effect The effect of treating multiple individuals is a linear function of treating one individual The effect of treating multiple individuals is a linear function of treating one individual

Difficulties TTO: people tend to value earlier years more than the later years TTO: people tend to value earlier years more than the later years SG same as TTO SG same as TTO Different estimates of the health state when you are in it Different estimates of the health state when you are in it Differences in risk taking behaviour Differences in risk taking behaviour Leaving out risk gives much greater relative weight to preventing or curing minor disabilities compared with major disabilities than do utilities Leaving out risk gives much greater relative weight to preventing or curing minor disabilities compared with major disabilities than do utilities Scaling problems (e.g. absence of disease versus perfect health) Scaling problems (e.g. absence of disease versus perfect health)