EBM

Question 1

Case Report

Answer 1

medical history of a single patient, retrospective

Question 2

Case series

Answer 2

history of several patients with a similar problem or outcome of interest (collection of case reports)

Question 3

Ecological study

Answer 3

Uses population data, as opposed to individual records (retrospective), might compare MMR vaccines with autism incidence to determine correlation

Question 4

Cross sectional study

Answer 4

data is collected from a representative sample of individuals at a specific time. Answers to a specific clinical question, a snapshot.

Question 5

Case-control study

Answer 5

identifies risk factors for a disease, not designed to evaluate effectiveness of treatment
People with a particular outcome are identified and matched with controls, controls are selected from the same population who do not have the condition but matched according to age, sex etc
Exposure to risk factor is compared and studied

Question 6

Cohort study

Answer 6

cohorts of people are selected on the basis of differences in their exposure to a particular agent (vaccine, drug), followed up over time to see how many people in each group develop a particular disease/outcome
Can also be used to determine prognosis of a particular disease

Question 7

RCT

Answer 7

each participant is randomly allocated to one group or another (treatment or placebo), both groups followed up and analysed (gold standard)
Groups should be similar apart from treatment

Question 8

Double Blinding

Answer 8

patients and staff unaware of which group is receiving treatment/placebo

Question 9

Crossover trial

Answer 9

compare responses of individual patients to two different treatments for the same condition, two groups who receive treatment A followed by B, and B followed by A

Question 10

Systematic review

Answer 10

high level overview of primary research on a particular research question, appraises all relevant evidence

Question 11

Meta-analysis

Answer 11

overview of a topic in which the results of all the included studies (several trials looking at the same drug) are similar enough statistically that results are combined and analysed as if it were one study
Statistical method used to pool all results and produce new results

Question 12

Reliability

Answer 12

extent to which experiment yields same result on repeated trials

Question 13

Validity

Answer 13

degree in which study accurately reflects what researchers set out to measure
Internal - integrity of experiment design, external - can results be applied to population

Question 14

Bias

Answer 14

ways study leads to particular conclusion, regardless of truth

Question 15

Incidence

Answer 15

number of new cases of a disease occurring in a population over a specific period of time

Question 16

Prevalance

Answer 16

proportion of people in a population who have a particular disease or attribute at a specific point in time

Question 17

Sensitivity

Answer 17

probability of correctly diagnosing a condition

Question 18

Specificity

Answer 18

probability of correctly identifying a non-diseased person

Question 19

NNT

Answer 19

average number of patients who need to receive treatment fro one of them to get a positive outcome in the time specified
Closer it is to 1, the more effective the treatment

Question 20

Absolute risk

Answer 20

somebody likelihood of developing a given disease over a period of time

Question 21

Relative risk

Answer 21

likelihood of people in one group developing a disease compared to (relative) people in another group

Question 22

Risk ratio

Answer 22

multiplication of risk that occurs with use of intervention

Question 23

Odds ratio

Answer 23

how much treatment affects event rate, probability of it occurring compared to it not occurring (intervention vs control)