ISI

Question 1

Population

Answer 1

Characteristics of participants in study and their disease. May include setting and defined inclusion and exclusion criteria.
Age, sex, disease, referred for RT by MDT for example

Question 2

Intervention

Answer 2

The novel therapy being evaluated.

Question 3

Exposure (in cohort studies)

Answer 3

What have they been exposed to, of which effect is unknown

Question 4

Comparator

Answer 4

Therapy or diagnostic with which novel intervention is being compared. Usually standard care for ethical reasons

Question 5

Outcome measures

Answer 5

Outcome measures that are defined prospectively - blood pressure, mortality rate etc.
End points in US studies
Usually one primary and several secondary

Question 6

Timing

Answer 6

Timing of the intervention, comparator, follow up etc.

Question 7

Bias examples

Answer 7

Admission rate
Attrition
Change over time
Deduction
Exclusion
Financial
Intervention
Lack of blinding
Lengthy treatment: bias due to drop out
Measurement
Operator
Performance
Selection
Spectrum

Question 8

Selection bias

Answer 8

Difference between groups in comparative study

Question 9

Spectrum bias

Answer 9

Influence of population choice on effect size

Question 10

Examples of limitations

Answer 10

Confounding
Underpowered/overpowered
Hawthorne effect
Single-centre
Not randomised?
Data collection process

Question 11

Confounding limitation

Answer 11

A variable that influences both dependent and independent variable
Problem with cohort studies

Question 12

Hawthorne effect

Answer 12

When individuals modify their behaviour because they are being observed

Question 13

Performance bias

Answer 13

Difference in care other than the intervention

Question 14

Exclusion bias

Answer 14

The drop out of one group more than the other which could lead to a bias in results

Question 15

Deduction bias

Answer 15

No blinding in assessor - shouldn’t know which group patient is in

Question 16

Case reports

Answer 16

Only have one patient

Question 17

Case series

Answer 17

Report a series of patients - no comparator group

Question 18

Cross-sectional survey

Answer 18

Survey hospitals to see what number of people they are treating with a disease at one point for example

Question 19

Case-controlled studies

Answer 19

Match case with control, intervene in one but not other

Question 20

Cohort study

Answer 20

Follow group over time that has had exposure or intervention

Question 21

RCT

Answer 21

Randomly put into groups - one has intervention and one doesn’t

Question 22

Meta analysis/systematic review

Answer 22

Pull together results from RCTs etc

Question 23

Intervention bias

Answer 23

Differences in the way the intervention was applied

Question 24

Measurement bias

Answer 24

Were they measured independetly

Question 25

Change over time bias

Answer 25

If patients were treated a long time ago the standard of care may have changed

Question 26

Attrition bias

Answer 26

Patients not seen through to the end may not be respresentative

Question 27

Admission rate bias

Answer 27

Occurs when only hospitalised participants are used - could be higher rate of issues or worst case of disease if they are hospitalised than general population

Question 28

Apprehension bias

Answer 28

When study participants responds differently because they are being observed
(can be behaviour, can be anxiousness)

Question 29

Lead time bias

Answer 29

Overestimating the survival time due to earlier screening than usual

Question 30

Volunteer bias

Answer 30

Participants volunteering to take part in a study intrinsically have different characteristics from the general population of interest.