November 6 Flashcards
Where are QALYs used? What is the formula?
-cost utility analyses -QALY= # life-years gained x quality of life -common metric to compare across many disease states
What is cost benefit analysis?
-look at all costs incurred when we see the results of a specific program -can be difficult because we need to know value of all inputs and outputs in our scenario -need direct and indirect costs and effectiveness of treatment
What are direct costs?
-direct medical costs: arise directly from treatment (diagnosis, drug therapy, medical care, etc.) -direct non-medical costs: arise from consequences of disease or treatment (transport costs, homecare, etc.)
What are indirect costs?
-changes in resources that occur not directly in relation to the treatment of a specific disease -overhead and capital -not attributable to specific medical services -spread over many medical services (hospital, electricity, admin, equipment) -lost productivity due to illness (usually gives more weight to higher paid patients) -does society really incur a cost in terms of missed work when someone is sick? in times of low employment, it will likely be easy to find someone to replace them -loss to leisure time due to illness (hard to assess)
What is opportunity cost?
- benefits foregone by particular use of resources
- difficult to quantify; market rates for goods and services (not always possible to determine socialized health care system where we don’t charge everyone for everything in a hospital), market rates for similar goods and services in other sectors of the economy (eg. can’t use bed and breakfast rate as a surrogate to hospital room and board)
- popular surrogate for opportunity cost is government reimbursment rates to physicians (may not always reflect true cost of the resource in question- decide which services we give up for the ones we decide to pay for)
What is the societal perspective about resource spending?
- include all resources that incur direct and indirect costs
- perspective decides which resources are to be “costed” in the economic evaluation
What is the payer perspective about resource spending?
- include only the resources that incur costs for the payer of interest
- usually talking about direct cost (OHIP covers these but does not cover indirect cost)
What are incremental cost effectiveness ratios? How are they calculated?
- used primarily to compare treatments in cost-effectiveness or cost-utility analysis
- assume we are in a situation with several alternative treatments but can only choose one (competing choice)
- allows us to determine the marginal cost for an additional unit of health benefit
- first compare standard of care with the next cheapest alternative, then compare this one with the more expensive one
- effectiveness measured as QALY
What is a cost-effectiveness plane?
- 4 quadrant graph
- NE quadrant: more effective and more costly
- NW quadrant: more costly and less effective
- SE quadrant: less costly and less effective
- SW quadrant: less costly and more effective
- often doesn’t relate to budget impact (may show a good ratio but if drug is cost is so high that the drug plan can’t pay for it it may not be useful option)
- can be difficult to interpret
What does modeling allow us to do? What is a decision tree?
- include all relevant data (multiple treatments and outcomes)
- simplified representations of complex systems designed to focus in on one specific question
- existing studies may not be comprehensive enough to include all of these data
- decision tree: identify choices, list possible outcomes, specify sequence of events, assign probabilities to chance events, assign values to all possible outcomes of chance events, calculate expected value of each strategy
- decision node is controlled by decision maker, chance not is not controlled by decision maker (circle), terminal node is final outcome (triangle) and all are mutually exclusive (if one happens the other can’t happen)
- can get complicated with many outcomes
What is sensitivity analysis?
- test the robustness of our results to changing model assumptions
- probabilities, costs, QALYs shown in models represent the base case
- rather than assume there is only one fixed success probability value we allow this success probability to vary
- variety of potential scenarios varying from base case to see the different ICERs
- uncertainty with how we estimate these things
What are difficulties with QALY assessments?
- can be difficult to translate health states into a utility score
- some states may be worse than death (negative utility score- eg. suicidal people may think death is better than other life states)
- some states may not be perceived as bad to some (people in wheelchair might consider themselves in perfect health)
