Study types Flashcards

1
Q

What does every single study have?

A

All components of PECOT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

List the 5 components of PECOT

A
Participants 
Exposure group 
Comparison group
Outcome 
Time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the two methods of data collection?

A

Numerical and categorical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is an example of a numerical data collection?

A

Weight in kg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is an example of a categorical data collection?

A

Not in numbers and is grouped into a category

E.g Underweight, normal weight, overweight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the measures of occurrence?

A

Incidence and prevalence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define incidence

A

Calculating the onset of disease for OVER a period of time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Define prevalence

A

Calculating the number of people with a disease at ONE point in time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which is the better measure of occurrence and why

A

Incidence
Keeps the denominator (i.e gives an idea of the proportion of people affected)
Not affected by the death and cure rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

When is an incidence measure used?

A

Used for dis-eases which have an easily observable onset

It is easy to tell when people transition from non dis-eased to dis-eased

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the two sub-types of a prevalence measure?

A

Point prevalence and period prevalence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is point prevalence?

A

Used for dis-eases when the onset is not as easy to observe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is period prevalence?

A

Dis-ease outcome is measured at one point in time BUT have occurred over a previous period of time

Used for dis-eases where the onset may be easy to observe but may come and go/vary in severity
E.g Asthma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 4 different study types?

A

Cohort study
Cross-sectional study
Randomised Control Trial
Ecological study

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a cohort study used for?

A

To investigate associations between risk factors (exposures) & dis- ease incidence in different groups of individuals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is an application of a cohort study?

A

When investigating the causes of dis-ease incidence.

17
Q

What are the design features of a cohort study?

A

Longitudinal, observational (non-experimental) Participants allocated to exposure & comparison by measurement
Dis-ease outcomes measured during follow-up

18
Q

What are strengths of a cohort study?

A

Usually cheaper than RCTs.
Exposure usually measured before outcome, avoiding recall bias and providing clear time sequence between exposure and dis- ease outcomes.

19
Q

What are some weaknesses of a cohort study?

A

Confounding is common.

Maintenance error very common in long term studies because exposure is not controlled by the investigators.

20
Q

Is a cohort study a prevalence or incidence measure?

A

An incidence measure

People tend to be followed over time (observational)

21
Q

What is a cross-sectional study used for?

A

To measure dis-ease prevalence in defined groups / populations of individuals. To investigate associations between risk factors & dis-ease prevalence in the group

22
Q

What is an application of a cross-sectional study?

A

Measuring the prevalence of dis-ease in different groups & populations

23
Q

What are some design features of a cross-sectional study?

A

Cross-sectional, observational, (non- experimental). Participants allocated to exp & comp by measurement Dis-ease outcomes measured at same time of allocation

24
Q

What are the strengths of a cross-sectional study?

A

Generally cheaper & can be completed more quickly than RCTs or cohort studies.
Best design for assessing the prevalence of dis-ease in a population.
No maintenance error as no follow-up

25
What are the weaknesses of a cross-sectional study?
Uncertain time sequence (possible reverse causality) limits interpretation of cause and effect. Confounding common
26
What is reverse causality?
When the outcome causes the exposure
27
What is an example of reverse causality?
When lifelong smokers are told they have lung cancer, many may then quit smoking. This change of behaviour after the disease develops can make it seem as if ex-smokers are actually more likely to die of lung cancer than current smokers
28
What is the key difference between a cross-sectional and cohort study?
A cohort study is measured overtime whereas a cross-sectional study is not.
29
What is the study objective of an ecological study?
To investigate associations between risk factors (exposures) & dis-ease prevalence or incidence in different groups of populations
30
What is an application of an ecological study?
Investigating trends and causes of dis-ease incidence and prevalence
31
What are the main design features of an ecological study?
Longitudinal or cross- sectional, non- experimental or experimental. Exposure and comparison allocated to groups rather than individuals
32
What are some strengths of an ecological study?
Generally cheaper & quicker than all other study designs because it uses data already collected. Useful when the majority of some populations are exposed but others are not. Efficient for rare outcomes
33
What are some weaknesses of an ecological study?
Confounding is extremely common
34
What is an objective of an RCT?
To investigate the effects of different interventions (exposures) on dis-ease incidence in different groups of individuals
35
What is the most useful application of an RCT?
Investigating the effects of interventions | e.g. new therapies
36
What are the main design features of an RCT?
Longitudinal, experimental. Participants randomly allocated to either study exposure or comparison exposure and dis-ease outcomes measured during a follow-up period
37
What is the strength of using an RCT?
Randomisation minimises confounding.
38
What are the weaknesses of an RCT?
Ethical limitations Logistically difficult as long-term follow-up difficult & costly. Large studies expensive, so usually too small (i.e. random error is a problem) Maintenance error common
39
What does double blind mean?
Neither the participant or researcher/person measuring the outcome knows what treatment is being given to the person.