03 Assessing Effectiveness Part 2

Question 1

What is the optimal course given by EU theory for the Medical Decision Making Paradigm?

Answer 1

Considers the value of each health outcome and the probability of each health outcome. The expected utility of a treatment is the sum of the product of each potential consequence’s probability-value pair

Question 2

Why is the EU theory good?

Answer 2

It always keeps you from becoming a health squanderer (no other theory is capable of this). It requires that your medical decisions are coherent and not inherently contradictory. No other approach to decision making can serve to achieve the goal of optimizing our health

Question 3

What is a Decision Tree?

Answer 3

Graphical representation of the clinical problem. Simplicity vs. Complexity tradeoff

Question 4

What are the components of a decision tree?

Answer 4

Decision nodes, Chance nodes, Outcomes

Question 5

What does a Square represent in the Decision Tree?

Answer 5

Decision node: Index of decision options

Question 6

What does a Circle represent in the Decision Tree?

Answer 6

Chance node: Partition of chance events

Question 7

What does do Triangles represent in the Decision Tree?

Answer 7

Outcomes: Consequences

Question 8

What are Quality-Adjusted Life Years (QALYs)?

Answer 8

Metric that integrates mortality and morbidity. A year in full health equals 1 QALY. A year dead equals 0 QALYs. Suboptimal health states are > 0 and < 1. QALYs accrue over time (10 years in a health state valued at 0.80 = 8 QALYs)

Question 9

What occurs in a Cost-Effectiveness Analysis?

Answer 9

Fund only the treatments that improve health at “reasonable” cost. Maximize health given budget constraints. Reduce the number of uninsured. Uses the concept of a QALY

Question 10

When assessing the desirability of outcome, what is Direct Utility Elicitation?

Answer 10

Utilities are elicited directly from respondents

Question 11

When assessing the desirability of outcome, what is Health State Classification Systems?

Answer 11

The respondent describes health status numeric utilities for a community reference group are mapped onto that health state

Question 12

What are the steps when valuing health?

Answer 12

Summarize health. Ask person to make tradeoffs. Find when they are indifferent between two choices. Compute a value

Question 13

What are the Elicitation Methods?

Answer 13

Standard gamble. Time tradeoff. Person tradeoff. Visual analog scale. Willingness to pay

Question 14

What is an example of a Standard Gamble?

Answer 14

There’s a “Sure Thing”: Lifetime of back pain. The “Gamble” is taking a surgery that could either 1) cause no more pain or disability, or 2) cause perioperative death

Question 15

What is Time Tradeoff?

Answer 15

Measures the health value by examining one’s willingness to live a shorter but healthier life. Tradeoff between remaining life expectancy and better health

Question 16

What is Person Tradeoff?

Answer 16

Seeks to equate a certain number of persons with a given health state with an equivalent number of persons with full health or a different health state. Example: How many lives saved is equivalent in social value to curing 1000 persons suffering blindness?

Question 17

What is the Visual Analog Scale?

Answer 17

Not choiced based. Yields an ‘experienced’ utility when used with patients. Easiest to complete. Suffers from context effects

Question 18

What is Willingness to Pay?

Answer 18

How much would you pay (in dollars) to reduce your health risk of X. Means to convert risk reduction to dollars. Used in cost-benefit analysis (CBA). CBA looks at costs and outcomes in dollars

Question 19

What are the limitations to Willingness to Pay (WTP)?

Answer 19

Wealth effects: WTP depends on wealth (must be careful to control for sample wealth level). Protected values (protest responses (health is priceless)). Anchoring effects. Endowment effect (buying and selling prices differ, i.e. coffee mug example). Not tied to real financial consequences

Question 20

What are the Health Classification Systems?

Answer 20

Quality of Well-Being Scale (QWB). Health Utilities Index (HUI). EQ-5D

Question 21

What is Discounting Health Benefits?

Answer 21

Good health today > good health in future. Diminishing the value of health over time is called “discounting”

Question 22

What is the Keeler-Cretin Paradox?

Answer 22

If health is discounted at a lower rate than money, the resulting CE ratio can be lowered by delaying the start of the intervention

Question 23

What is Equity?

Answer 23

Preference for the distribution of health to the population. Often competes with efficiency (CE-ratios make an efficiency claim: maximize health of population)

Question 24

Why adjust for equity in CEA?

Answer 24

Poly makers less likely to dismiss CE results. Beneficiaries may want to trade some efficiency for greater equity. Makes explicit the equity component of policy decision making (Transparency of process, Greater public awareness, Reduces use of heuristic decision making)

Question 25

What can deviations from pure efficiency (expected utility) unwittingly result in?

Answer 25

Policies that make everyone worse off

Question 26

What is an example of an efficient vs. equitable plan?

Answer 26

Efficient: Some people are doing REALLY well while others are not. Equitable: Brings down the people doing really well, but increases the ones not doing well to make it a little more even.

Question 27

How are QALYs associated with costs?

Answer 27

QALYs need to be discounted at the same rate as costs

Question 28

What is the summary for QoL?

Answer 28

QoL weights are susceptible to bias and need to be adjusted

Question 29

What is the Sequential approach?

Answer 29

Check for effect difference. If ‘no effect’, check for cost difference (cost minimization). If ‘effect’, check for cost difference (cost effectiveness analysis)

Question 30

What is the Sequential null hypothesis significance testing?

Answer 30

Statistical test that calculates the chance of observing the data assuming no difference between groups exists (null hypothesis)

Question 31

Why is Sequential hypothesis testing problematic?

Answer 31

Failure to detect health effects are likely influenced by Type II errors. Type II errors are de-emphasized in sequential NHST. Cost-minimization analysis is thus over-utilized

Question 32

What are some techniques to avoid sequential analysis?

Answer 32

Bootstrapping. New statistics

Question 33

What is Bootstrapping?

Answer 33

A self-sustaining process that proceeds without external help. “to pull yourself up by your bootstraps”. Pharmaceutical economics (Repeating a process a large number of times to generate an empirical distribution of cost-effectiveness)

Question 34

What is assumed in Bootstrapping?

Answer 34

Treatment condition. Control condition. Cost for each participant. Effect measure for each participant. Bootstrapping requires RCT data

Question 35

What is Risk Stratification?

Answer 35

Often times cost-effectiveness depends on risk group. Risk groups are the factors that affect the size of the QALY gain from and/or cost of the intervention. We may plot acceptability curves with respect to risk groups. From this we understand who may benefit the most from an intervention

Question 36

What is the Net Benefit Framework?

Answer 36

It is possible to express cost-effectiveness purely in dollars. It is possible, also, to express cost-effectiveness purely in terms of effects. An advantage is that this approach has better statistical properties than CE ratios

Question 37

What is Statistical Power and Net Benefit?

Answer 37

Suppose you are reviewing a study that reports “no significant net benefit” for Treatment X over Treatment Y. How do you know they had enough power to detect an effect? Compute needed sample based on variance of net benefit statistic, alpha to reject NMB = 0, ceiling ration and desired statistical power level