what are the 4 stages of an MI enquiry
- understand the question - get enquirer details and details of the question
- research - find the same answer in many sources and cite them
- prepare answer - only answer if competent
- feedback answer - send it to enquirer
make sure to document every stage
what is are the 4 stages of EBP
1) ask a good question
- make several specific questions
use PICO
2) acquire best evidence
- find search terms
- use primary and 2ndry sources
3) appraise quality of guideline
- use checklist
4) apply evidence to your patient
what is PICO
PICO is how you turn a patient problem into a question
P - patient and problem
I - intervention
C - comparison choices
O - outcome
Equation for incidence rate
Number of new cases/disease free person time at risk = Incidence rate
Number of new cases of disease/ Mid-year population = Incidence rate
Incidence Density (rate) equation
Incidence density = Number of new cases / Disease-free person time at risk
e.g. 2 cases/24 person years = 0.083 per year
Considerations when calculating incidence - 3
Considerations when calculating incidence - 3
1. Disease relapsing
2. Disease remaining undiagnosed
3. Is the population stable
what is the equation for disease prevalence
Number of cases/ Number of people in the population = Prevalence
Will always be between 0 & 1
Can be given as a percentage
what are the risk equations
Outcome No outcome
Exposed 150 600
Unexposed 45 855
Absolute risk difference = 150/45 - 45/900 = 4
Risk Ratio = 150/(150+600) / 45/ (45+855) =15/100
how do you calculate number needed to treat
Cured Not cured
New treatment 600 400
Old treatment 200 800
Absolute risk difference= 600/1000
- 200/1000 = 400/1000
NNT 1/(400/1000) = 2.5
Round to 3
what is a meta analysis
statistical methods for combining the results of a number of studies
what is bad about systematic reviews
difficult to give one overall result usually a range is given
has a risk of bias
what is bad about meta analysis
bias as not all studies may be included
what are bad about observations studies - 2
- non experimental
- no control over variables
what are the strengths and limitations of cohort studies - 4
- efficient for rare exposures
- multiple effects can be studied
- can calculate risk and incidence rate
limitations
4. still has bias
what are the strengths and limitations of case control studies - 7
- quick results and cheap
- good for rare diseases
- looks at many factors
- inefficient for rare exposure
- cant calculate incidence
- difficult to establish time relationships
- more prone to bias than cohort
what is confounding
it is the distortion of the risk estimate
what is pharmacovigilance
detecting unknown adverse effects and interactions
identify risk factors
