Study designs: experimental

Question 1

randomised control studies are most similar to _____ in that

but the main difference is

Answer 1

prospective control studies
start with exposure, look into future to see outcome

unlike PCS, exposure is RANDOMLY ALLOCATED

Question 2

ethics associated with random allocation?

Answer 2

if exposure is harmful - eg smoking - then random allocation would be unethical

Question 3

how do RCTs control for selection bias

Answer 3

allocation concealment

Question 4

how do RCTs control for performance and detection bias

Answer 4

double blind

Question 5

addition to double blind?

Answer 5

using a placebo

Question 6

use of placebo is aka

Answer 6

double dummy effect

Question 7

confounding resulting from use of placebo? name and define

Answer 7

placebo effect: person think’s placebo’s real, acts accordingly

Question 8

ethics associated with a placebo

Answer 8

people might think they’re having a life saving treatment when they’re not

Question 9

control for attrition bias?

Answer 9

make sure patients commit to experiment before exposure is allocated.

Question 10

crossover trial - describe

Answer 10

randomly allocated to one of two groups
group 1 is exp first, group 2 control. outcome measured
washout period
group 2 is then exp, group 1 is control. measure outcome

Question 11

2 advantages of crossover trial

Answer 11

sample size essentially doubled

patients serve as own controls

Question 12

disadvantage of crossover trial

Answer 12

ethics

Question 13

n of 1 trial

Answer 13

like crossover but just one person

Question 14

disadvantage of n of 1 trial

Answer 14

one person so limited generalisability

Question 15

desribe cluster RCT/community trials

Answer 15

unit of randomisation is a cluster of people - eg. patients of a particular GP, hospitals

Question 16

advantage of cluster RCT

Answer 16

people in one cluster are less likely to associate with people of another cluster, reducing contamianation

Question 17

describe field trial

Answer 17

RCT is done out in the commuinity

Question 18

define systematic review

Answer 18

inolves rigorously analysing and evaluating multiple RCT

Question 19

systematic vs narrative review?

Answer 19

systematic is more rigorous

Question 20

first step of systematic review

Answer 20

formulate structured clinical question

Question 21

then

Answer 21

make criteria

• inclusion/exclusion
• quality

Question 22

then

Answer 22

do the literature search, documenting search strategy

Question 23

then

Answer 23

select studies for inclusion and determine quality

Question 24

then

Answer 24

do the metaanalysis - make weighted average