Amboss Epidemiology

Question 1

what is classical epidemiology

Answer 1

the study of distribution and determinants of disease in populations

Question 2

what is clinical epidemiology

Answer 2

this is applying classical epidemiology to the prevention, detection, and treatment of disease in a clinical setting

Question 3

what are the two main types of epidemiological studies?

Answer 3

observational and experimental

Question 4

what is the latency period

Answer 4

period of inactivity between stimulation (infection with the pathogen) and response (symptomatic)

Question 5

what is a random error

Answer 5

an error that occurs by chance and or limitations of precision

Question 6

how can we reduce random error

Answer 6

repeated measurements and a large number of observations

Question 7

what is systematic error

Answer 7

aka bias

an error in the way in which a study is conducted that causes a systematic deviation of findings from the true value

Question 8

what is selection bias

Answer 8

bias when people in a sample group are not representative of the population from which the sample is drawn from (not random selection)

Question 9

types of selection bias

Answer 9

sampling bias - nonresponse bias

attrition bias (loss of participation to follow up)

Berkson (all patients are selected from a hospital)

Question 10

attrition bias is most commonly seen in what type of studies

Answer 10

attrition

Question 11

solution for selection bias

Answer 11

control for unknown and known confounders

Question 12

what is information bias

Answer 12

when data is collected incorrectly, measurements or interpretations leads to misclassification of groups or exposure

Question 13

types of information bias

Answer 13

measurement

performance

recall

Question 14

what is measurement bias

Answer 14

a systematic error that occurs when you measure the exposure or outcome

Question 15

what is performance bias

Answer 15

there are differences between the study groups that are related to group assignments

hawthorn; subjects change their behavior when they are aware that they are being observed

Question 16

recall bias

Answer 16

awareness of a condition by the patients changes how much they recall the related risk factors (common in retrospective studies and is reduced by decreasing time to follow up with them)

Question 17

misclassification bias

Answer 17

research subjects are classified into the wrong exposure or outcome group which then distorts the observed association

Question 18

cognitive bias

Answer 18

personal beliefs of the participants or investigators influences the results of the study

Question 19

observer bias (type of cognitive bias)

Answer 19

aka pygmalion effect

the outcome or measurements of the study is influenced by the researches knowledge or beliefs

(avoided using placebo and blinding)

Question 20

what is a confounder?

Answer 20

a third variable that is associated with the exposure and the outcome

can be responsible for an observed relationship between the dependent and independent variables

Question 21

how can you minimize confounding variables during study design?

Answer 21

randomization, crossover study design

Question 22

how can matching be done in studies

Answer 22

participants are matched individually to other participants with similar attributes

done in case-control studies to avoid confounders

Question 23

Hazard Ratios

Answer 23

a measure of relative risk in statistical analyses

a HR greater than 1 is an increased risk
a HR less than 1 indicated a decreased risk