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Flashcards in Epidemiology Deck (35):
1

Define prevalence

refers to existing cases

2

define incidence

refers to NEW cases over an unaffected population

3

how to calculate risk?

risk= new cases/population at risk

4

how to calculate rate?

rate= new cases in time period/ total follow up

5

what is hazard?

instantaneous rate for longitudinal studies

6

how to calculate relative risk?

risk exposed/ risk Unexposed (re/ru)

7

how to calculate attributable risk?

risk exposed - risk unexposed (re-ru)

8

how to calculate attributable risk %

(attributable risk/ risk exposed) x 100

9

what do we mean by non longitudinal and longitudinal studies?

longitudinal= follow up
non longitudinal= no follow up

10

what types of studies are found in longitudinal studies

cohort studies
clinical trials

11

what types of studies are found in non longitudinal studies?

cross sectional
case control

12

describe a CASE control trial

2 groups
RARE outcomes
Odds ratio calculated (likelihood of getting disease)

13

how do accurate odds ratio?

ad/bc

14

what are the two types of bias?

selection
informational

15

how to prevent selection bias?

careful recruitment, minimise loss to follow up

16

how to prevent information bias?

standardised tools

17

what is a confounder?

a variable that influences the relationship between Exposure and Outcome

18

what is the gold standard sort of trial that ix evidence of causality?

clinical trials

19

what are some key considerations of clinical trials?

randomisation
blinding
intention to treat analysis
hazards ratio
number needed to treat

20

how to calculate the hazard ratio HR?

hazard (intervention) : hazard (control)

21

what is the number needed to treat?

the no of ppl that are needed to undergo the intervention in order to prevent outcome in one

22

what does it mean when HR (hazard ratio) is 0.8?

the probability that the intervention will reduce outcome is 20%

23

why is NNT important in a clinical trial?

demonstrates the efficacy of the intervention

24

how to calculate NNT?

1/ absolute risk or rate reduction

25

what do we mean by absolute reduction?

difference between rate of outcome in control group and rate of outcome in intervention group

26

what type of study is considered the best level of evidence

randomised control studies/clinical trials

27

how do we assess internal validity?

PICOT
population
intervention
comparator/control
outcome
timing

28

what does a small confidence interval suggest?

narrow= precise or smaller sample size

29

what does are large confidence interval suggest?

wide= less precise or larger sample size

30

how to calculate SENSITIVITY

true positive/ (true positive + false negative)

TP/ (TP + FN)

31

how to calculate SPECIFICITY

true negative/ (true negative + false positive)

TN/ (TN + FP)

32

how to calculate PPV (positive predictive value)

true positive/ (true positive + false positive)

TP/ (TP+ FP)

33

how to calculate NPV (negative predictive value)

true negative/ (true negative + false negative)

TN/ (TN + FN)

34

how to calculate likelihood ratio of +ve test?

sensitivity/ (1- specificity)

35

how to calculate LR of a -ve test?

(1-sensitivity)/ specificity