module 1

Question 1

definition of epidemiology

Answer 1

the study of how much dis-ease occurs in groups and of the factors that determine differences in disease occurrence between 2 groups

Question 2

what do epidemiologists do

Answer 2

measure the frequency of health and disease in different poppulations to find out the causes of poor health and how to improve it

Question 3

key difference in epidemiology

Answer 3

describe the population

Question 4

why do we age standardise

Answer 4

populations have different age structures that can cause confounding

Question 5

what is a cohort study

Answer 5

not random and occurs over time where relevant disease events are counted - longitudinal and observational

Question 6

cross sectional study

Answer 6

measure prevalence - measure outcome and exposure at the same time - can measure prevalence during incidence

Question 7

when do you use incidence vs prevalence

Answer 7

incidence - mortality and easy to measure - prevalence - hard to measure

Question 7

how are cohort allocated

Answer 7

by measurement

Question 8

period prevalence

Answer 8

backwards and diagonal t but still prevalence as incidence only measures forward in time - eg asthma

Question 9

categorical vs numerical

Answer 9

yes. or no or greater or less than vs mean averaged

Question 10

epidemic vs pandemic

Answer 10

epidemic = occurrence of disease that is in excess of normal
pandemic = epidemic in multiple countries

Question 11

high incidence and low prevalence

Answer 11

people die or get cured rapidly - eg cold

Question 12

low incidence high prevalence

Answer 12

eg bmi - cant measure over time but can in one point in time

Question 13

strengths and weakness of incidence

Answer 13

determined by disease risk in population - clean measure - over time - maintenance and allocation error - takes long

Question 14

prevalence strengths and weakness

Answer 14

less info than incidence - dirty measure - easy to measure

Question 15

ecological study

Answer 15

participants are countries - confounding as different factors are faced eg diet and outside influence

Question 16

difference between rct and cohort

Answer 16

randomly allocated to eg and cg

Question 17

benefits of rct

Answer 17

similar baseline qualities and comparison to measure effects of exposure - = chance of being assigned to eg or cg if study is big enough - often not though so smaller studies are combined - decreased confounding
ethicality - cant test a lot of things if it has shown harm - less participants as well - expensive - experimental

Question 18

double blind

Answer 18

neither participant or researcher knows the exposure - prevents subjective measures and placebo - researcher kept separate

Question 19

single blind

Answer 19

researcher knows

Question 20

error with rct

Answer 20

random sampling or random allocation - also maintenance over time

Question 21

rr vs rd

Answer 21

rr no units rd same as ego and cgo
rr = ego/cgo rd = ego-cgo
relative risk reduction = less than 1 and increase = more than 1
use rd instead of rr to measure disease risk and if cgo is small then benefit from treatment will be small

Question 22

ramboman - non random

Answer 22

recruitment
allocation - reduce this by meta analysis or strata
maintenance
blind objective measurement
analysis

Question 23

low response rate

Answer 23

bad rep of total pop

Question 24

confounding

Answer 24

when factors other than exposure contribute to the outcome so study has bias

Question 25

random error and how to reduce

Answer 25

extreme events due to chance - regression to the mean by repeating trials with extreme results

Question 26

random sampling error

Answer 26

every sample will be different - smaller sample = less rep of pop = greater error

Question 27

what is ci for

Answer 27

measure of range of random error in estimate of cgo ego rr and rd if only one study is done

Question 28

example of ci

Answer 28

there is about 95% chance that the true value in a population lies within the 95% ci

Question 29

if ci of cgo and ego do not overlap

Answer 29

stat sig difference

Question 30

if ci of rr rd and no effect line dont overlap

Answer 30

stat sig diff

Question 31

if large ci overlap between ego and cgo

Answer 31

study unable to determine if ego and cgo differ and so results are not stat diff as too much random error

Question 32

systematic reviews and meta analysises

Answer 32

mainly in rct due to being small - lots of trials and keep good ones - reduce random error

Question 33

reverse causality

Answer 33

which came first - exposure or outcome

Question 34

to determine link between exposure and outcome

Answer 34

need sufficient studies in diverse settings and little random error non random error and confounding

Question 35

tb

Answer 35

poverty, poor sanitation, overcrowding and reduced immunity