03 Assessing Effectiveness Part 2 Flashcards
What is the optimal course given by EU theory for the Medical Decision Making Paradigm?
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
Why is the EU theory good?
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
What is a Decision Tree?
Graphical representation of the clinical problem. Simplicity vs. Complexity tradeoff
What are the components of a decision tree?
Decision nodes, Chance nodes, Outcomes
What does a Square represent in the Decision Tree?
Decision node: Index of decision options
What does a Circle represent in the Decision Tree?
Chance node: Partition of chance events
What does do Triangles represent in the Decision Tree?
Outcomes: Consequences
What are Quality-Adjusted Life Years (QALYs)?
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)
What occurs in a Cost-Effectiveness Analysis?
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
When assessing the desirability of outcome, what is Direct Utility Elicitation?
Utilities are elicited directly from respondents
When assessing the desirability of outcome, what is Health State Classification Systems?
The respondent describes health status numeric utilities for a community reference group are mapped onto that health state
What are the steps when valuing health?
Summarize health. Ask person to make tradeoffs. Find when they are indifferent between two choices. Compute a value
What are the Elicitation Methods?
Standard gamble. Time tradeoff. Person tradeoff. Visual analog scale. Willingness to pay
What is an example of a Standard Gamble?
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
What is Time Tradeoff?
Measures the health value by examining one’s willingness to live a shorter but healthier life. Tradeoff between remaining life expectancy and better health
What is Person Tradeoff?
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?
What is the Visual Analog Scale?
Not choiced based. Yields an ‘experienced’ utility when used with patients. Easiest to complete. Suffers from context effects
What is Willingness to Pay?
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
What are the limitations to Willingness to Pay (WTP)?
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
What are the Health Classification Systems?
Quality of Well-Being Scale (QWB). Health Utilities Index (HUI). EQ-5D
What is Discounting Health Benefits?
Good health today > good health in future. Diminishing the value of health over time is called “discounting”
What is the Keeler-Cretin Paradox?
If health is discounted at a lower rate than money, the resulting CE ratio can be lowered by delaying the start of the intervention
What is Equity?
Preference for the distribution of health to the population. Often competes with efficiency (CE-ratios make an efficiency claim: maximize health of population)
Why adjust for equity in CEA?
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)
What can deviations from pure efficiency (expected utility) unwittingly result in?
Policies that make everyone worse off
What is an example of an efficient vs. equitable plan?
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.
How are QALYs associated with costs?
QALYs need to be discounted at the same rate as costs
What is the summary for QoL?
QoL weights are susceptible to bias and need to be adjusted
What is the Sequential approach?
Check for effect difference. If ‘no effect’, check for cost difference (cost minimization). If ‘effect’, check for cost difference (cost effectiveness analysis)
What is the Sequential null hypothesis significance testing?
Statistical test that calculates the chance of observing the data assuming no difference between groups exists (null hypothesis)
Why is Sequential hypothesis testing problematic?
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
What are some techniques to avoid sequential analysis?
Bootstrapping. New statistics
What is Bootstrapping?
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)
What is assumed in Bootstrapping?
Treatment condition. Control condition. Cost for each participant. Effect measure for each participant. Bootstrapping requires RCT data
What is Risk Stratification?
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
What is the Net Benefit Framework?
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
What is Statistical Power and Net Benefit?
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
