Evidence and Clinical Questions Flashcards
PICOS
population, intervention, comparison, outcome, study design
Cross sectional study
Descriptive epidemiology
Can help form a hypothesis
2 types of analytical epidemiology
experimental (randomized controlled trials)
observational (case controlled and cohort)
Types of reviews
lit review- subjective and cannot be replicated, systematic and nonsystematic methods
systematic review- clear and specific research question, inclusion/exclusion criteria
meta-analysis- pooled individual studies, increase precision of estimates and synthesize findings across populations
Challenges in lit review
-large number of studies
-Inconsistent terminologies
-different statistical methods
Systematic review steps
- write protocol
- search literature
- review titles, abstracts and full texts
- abstract data
- assess risk of bias
- summarize evidence
extra steps for meta analysis
6. assess heterogeneity
7. obtain pooled measure of association
8. assess publication bias
where do you report systematic reviews?
PRISMA
diamonds
diamonds are associated with 95% confidence intervals,
if diamonds do not cross the null, there is a statistically significant effect
if heterogenetity
use a random effects model
if no significant heterogeneity
use a fixed effects model
or random effects model (assume true population)
subgroup analysis
use with caution, tires to make inferences about a specific group
sensitivity analysis
analysis using alternative decisions (ex different inclusion criteria)
assess publication bias
many journals do not want to publish negative or null results so are naturally biased against them
funnel plots can assess publication bias
no bias= symmetrical mountain
I^2>50%
not due to random chance
due to one or more factors
is it reasonable to pool results if they are very heterogeneous
no
efficacy vs effectiveness
efficacy- produce results under ideal clinical trial conditions
effectiveness- produce results in real clinical use
know graph of constant effect, lagged benefits, and compounded returns to intervention
slide 47
common metrics of effectiveness for health
-QALYs/DALYs (best practice)
-life expectancy
-# cases averted
-# of diagnoses
-# follow-up care visits
effectiveness
RRR= .8
baseline risk= .5
population= 100
.5100= 50
.8.5*100= 40
effectiveness= 10 cases averted
return on investment
current value- cost of investment/ cost of investment
cost-effective
cost of producing additional benefit from intervention is good value for money
cost saving
intervention cost less money (accounting also for future saved costs)
2 prevention services found to be cost saving
childhood immunizations
counseling on low dose aspirin to prevent stroke
CEA- cost effectiveness analysis
most common type used in healthcare
cost or change in cost/ health effects or change in health effects
ICER
incremental cost-effectiveness ratio
ICERb= (Costb - Costa)/ (health effect b- health effect a)
life table method
QALYs state = HRQLstate x PersonYearsstate
ICER threshold
less than $100K (MARGINAL COST) per QALY gained
QALY
cost/ (1+1=0.03)^t
Other reasons to make health decisions
clinical duty
ethical study
equality/justice
patient preference
economic efficiency
