Lectures 9 - 13 for Final Flashcards
(121 cards)
Value of a statistical life (VSL):
Threshold current = $7M
■ If intervention costs more → reject
■ If intervention costs less → accept
How are VSL’s determined?
Juries
● Revealed preference (willingness to pay)
● Revealed preference in occupation (ex. window washer wage differs depending on the height at which they wash; coal miners)
● Survey
Cost-Benefit Analysis (CBA)
- Convert Everything to Dollars
- Do the costs outweigh the benefits?
- Assumes a constant VSL
- Used more in regulation than in medicine/PH
Cost-Effectiveness Analysis (CEA)
Cost-effective
Incremental Cost Effectiveness Ratio/Cost-Effectiveness Ratio
Difference in costs / Difference in Effectiveness;
[Cv-Co]/[Ev-Eo]
Cost-Utility Analysis
Same as cost-effectiveness but units is QALYs or DALYs
What is considered a QALY threshold for cost-utility analysis?
$50k-$100k per QALY; in LIC use per capita GDP
Discuounting
PV = FV/[(1+r)^t]
You often need to compare stuff over time (i.e. chronic disease - cheaper to prevent or treat later)?
Need to use this to compare the future vs today
3% is seen as the starting discount rate for medical decision making
If you have 10mm people and the cost of a vaccine is $2; what is your cost to vaccinate all?
2*10mm = $20mm
If you have 10mm people and 99.5% of the people who are vaccinated live, how many people will live?
.995*10mm= 9.95 milliion lives saved
If you have 10mm people and vaccinate none of them, and 99% get no small pox, and of the 1% that do, 10% live, how may people are alive at the end?
.9910mm=9.9 million lives
plus
(0.010.10)*10mmm = 0.01mm
= 9.91mm lives
If total cost of vaccination = 20,000,000 and total cost of not = 0, and effectiveness for vaccination (aka lives saved) is 9.95mm and effectiveness for non-vaccination is 9.91mm, then what is the value per life saved?
(20,000,000-0)/(9.95-9.91) = 20,000,000,/.04= $500/lives saved.
Reminder to look at Heparin Decision Tree Example
Look at example
Sensitivity
P(T+|D+)
Specificity
P(T-|D-)
PPV:
P(D+|T+) = [sensprevalence]/[(sensprev)+(1-spec)*(1-prev)]
Where is the prevalence located on a 2x2?
bottom of the D+ column (“e” cell)
What is cell a as a calcuation?
prevalence*sensitivity
what is d cell as a calucation?
F cell*specificity
What is the calculation for PPV also?
a cell divided by total test positive.
What do we fear in testing?
false positivies
When does it make sense to screen?
When the A cell is way more heavily populated than the b cell.
When can we expect more false positives?
when the disease is very rare
review HIV example
review HIV example