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Flashcards in Final Epidemiology Deck (39)
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1

Sensitivity

Proportion of persons w/ dz w/ + test

2

Specificity

Proportion of persons w/o dz w/ - test

3

Positive Predictive Value (PPV)

Proportion of pt w/ + test who have the dz
*PPV is closely related to the prevalence

4

Negative Predictive Value (NPV)

Proportion of pt's w/ - test who do NOT have the dz

5

Sn-N-OUT Rule

Sensitivity is high, you can RULE OUT the dz if test comes back -

6

Sp-P-IN Rule

Specificity high then you can rule in the dz if test comes back +

7

LR+

Probability of + test for person w/ dz divided by probability of + test for person w/o the dz
= Sensitivity / (1 - Specificity)

8

LR-

Probability of - test for person w/ dz divided by probability of - test for person w/o dz
= (1 - Sensitivity) / Specificity

9

LRs to "rule in" dz

> 10: strong
5-10: moderate
2-5: weak

10

LRs to "rule out" dz

0.2 - 0.5: weak
0.1 - 0.2: moderate
< 0.1: strong

11

Parallel Testing

Order several tests @ once, useful for rapid assessment situations
- maximizes sensitivity and NPV
*e.g. - CP in the ED order CK and Troponin, etc.

12

Serial Testing

Order next test on basis of prior result, useful when assessment can be done over time or tests are expensive
- maximizes specificity and PPV
*e.g. - serial troponins for a CP pt in ED under obs

13

Benefits of Screening

Earlier detection leads to better outcome, test has good sensitivity/specificity, burden of dz in community warrants test, resources available to follow-up + tests

14

Primary Prevention

Identify risk factor for dz and reduce exposure, promote resistance
*e.g. - immunization

15

Secondary Prevention

Identify early dz before signs/sx's start
*e.g. - screen for DM

16

Tertiary Prevention

Dz has been identified but prevent advanced development, side effects, and outcomes etc.
*e.g. - pt w/ DM educate to prevent loss of sight/limb

17

Cumulative Incidence (Risk)

Probability of an individual developing dz during a specific timeframe, using # of persons @ risk for the denominator

18

Incidence Density (person-time)

Probability of an individual developing a dz during specific period of time using total person time as the denominator

19

Case Reports

Describe the experience of a single pt (n = 1) w/ an interesting finding
*no comparison

20

Case Series

Describe the experience of a group of pt's (n > 1) w/ similar dx's
*no comparison group

21

Cross-Sectional Studies

Aka Prevalence Study, exposure and dz status assesed @ single point in time, individual is unit of observation and analysis, no cause-effect and no incidence known
*dz or no dz -or- exposed or unexposed
*common analysis is Chi square

22

Case-Control Study

Key comparison: Dz vs. No Dz
- no prevalence or incidence assessed; measure risk of exposure to risk factors in dz group vs the no dz group retrospectively

23

Cohort Study

Key comparison: Risk factor vs. No Risk Factor, groups followed over time to see who ends up developing the dz, assesses incidence and causality but not prevalence

24

Intention-to-treat Analysis

Analyze according to group initially assigned regardless of whether they received tx

25

Explanatory Analysis

Analyze according to tx actually received, regardless of randomization

26

Efficacy setting

Analyzing tx in ideal setting

27

Effectiveness setting

Analyze tx in ordinary circumstances; usual pt care

28

Relative Risk Reduction

Describes the magnitude of the effect; represents the % reduction in risk of studied outcome achieved by the use of the intervention

29

Absolute Risk Reduction

Describes the risk difference in outcome btwn pt's who have undergone 1 therapy and those who have not

30

Number Needed to Treat

NNT = 1/AR
*if you're looking @ the treatment