Pharmacoepidemiology

Question 1

what is Pharmacoepidemiology

Answer 1

it is the study of the use and effects of drugs in large numbers of people

Question 2

State pharmacoepidemiological studies

Answer 2

1) Observational studies in which the subjects are observed and data recorded with no changes to the natural course of exposure or treatment. there are two types of observational studies

Descriptive studies: such as case reports, case studies and cross-sectional descriptive studies

Analytical studies: these allow the calculation of measures of risk relating to exposure and outcome such as case-control and cohort studies

2) experimental studies
these studies are often known as intervention studies as the observers design the nature of treatment or exposure to allow the comparison of exposure and outcome in two or more groups to analyse and quantify the effects of either exposure or treatment

Question 3

study design summary

Answer 3

study design
|
observational
| - case-control
descriptive, analytical - cohort
|
case report, case series, cross-sectional descriptive studies

Question 4

what is absolute risk

Answer 4

it is the incidence of a disease in a certain population.

it indicates the magnitude of risk in a group of people with a certain exposure

does not consider the risk of disease in non-exposed individuals

does not indicates whether exposure is associated with an increased risk of disease

Question 5

what is the formula for absolute risk

Answer 5

AR = no of events / no of exposed

Question 6

what is attributable risk

Answer 6

it is the difference in the occurrence between exposed and unexposed groups in a population

a useful measure of the extent of the problem caused by an exposure

usually used in RCTs

Question 7

what is the formula for AtR

Answer 7

risk of exposed group- risk of unexposed group

Question 8

what does risk difference and AtR values means

Answer 8

+ve means increase risk by the exposure
-ve means decrease decreased risk by the exposure

Question 9

what is relative risk (risk ratio)

Answer 9

it is the probability of an event occurring in exposed individuals compared to the probability of an event occurring in non-exposed individuals
it is a good indicator of the strength of the relationship

Question 10

what is the formula of RR

Answer 10

RR = AR in exposed / AR in unexposed

• AR = no of events / no exposed

Question 11

what does RR values mean

Answer 11

RR=1 risk of outcome is no different due to the exposure

RR > 1 risk of outcome is higher in those exposed to those unexposed ( +ve association possibly casual)

RR<1 risk of outcome is lower in those exposed to those unexposed (-ve association possibly protective)

Question 12

what is an Odd ratio

Answer 12

it is an alternative way of comparing how likely events are between two groups

it is a measure of the association between exposure and an outcome

Question 13

what is the formula for OR

Answer 13

OR = odds of the event in one group/odds of the event in the other group

Question 14

what does OR values mean

Answer 14

OR = 1 odds of the outcome are unchanged due to the exposure

0R > 1 odds of the outcome is increased by the exposure (+ve association possibly casual)

OR<1 odds of the outcome decreased by the exposure (-ve association possibly protective)

Question 15

what is confidence intervials

Answer 15

aim to give you an idea of how confident you can

Question 16

what is confidence intervials

Answer 16

aim to give you an idea of how confident you can be about the findings. the narrower the range the more accurate and precise the estimates and the more confident you can be about the findings being real and not due to chance

Question 17

what is absolute risk reduction

Answer 17

it is the absolute arithmetic difference in the rate of bad outcomes between the control group and the treatment group

Question 18

what is the formula for ARR

Answer 18

ARR = ARC - ART

Question 19

difference between ARR and AtR

Answer 19

ARR= ARC-ART
AtR= RT-RC

in AtR the probability of disease is going down due to treatment and in ARR the probability of disease is going up due to exposure

Question 20

what is Relative Risk Reduction?

Answer 20

RRR tells us how much the treatment reduced the risk of bad outcomes in relative to the control group who were not treated

Question 21

what is the formula of RRR

Answer 21

RRR = ARC - ART / ART

Question 22

what is NNT

Answer 22

the number needed to treat indicates the number of patients that will be needed to treat over a given period of time to prevent one bad outcome

NNT = 1 everyone improves with treatment the higher the number the less effective the treatment

Question 23

what is the formula for NNT

Answer 23

NNT= 1/ARR

Question 24

states types of association

Answer 24

direct or casual
artifactual
confounded

Question 25

pharmacoepidemiological studies importance

Answer 25

used to supplement pre-marketing studies as these are usually not long in time, use small samples, cohorts are not representative of the population and for other ethical and practical issues

Question 26

Define health screening

Answer 26

is the process of using tests on a large scale of people to identify diseases in apparently healthy people

they do not usually establish a diagnosis but rather the presence or absence of an identified risk factor

the screening test should be cheap, easy to apply , reliable, acceptable to public and valid

Question 27

what are the main approaches to health screening

Answer 27

1) opportunistic
2) mass
3) targeted

Question 28

what is sensitivity

Question 29

what is specificity