THEME 2b Epidemiology

Question 1

define epidemiology

Answer 1

study of how often diseases occur in different groups of people and why

Question 2

What are the 3 components of epidemiology?

Answer 2

1. Distribution
2. frequency
3. deteminants (derived from data 1. and 2., neccesary to test an epidemiologic hypothesis

Question 3

What is this the process of :
A suspicion exists that a particular factor may be influencing the occurrence of a disease. (Your suspicion may arise from clinical practice, observation, research etc).
Formulation of a specific hypothesis.
Hypothesis is tested in epidemiological studies with a comparison group.
Collect and analyse data to determine whether a statistical association exists.
Assess validity of any observed association by excluding alternative explanations such as chance, bias and confounding.
Does statistical association suggest a causal relationship? (Consider the magnitude of the association / other studies / consistency of findings against other studies / biological credibility)

Answer 3

epidemiology

Question 4

How can you measure disease?

Answer 4

1) Indices
2) Standardisation
3) Quantifying disease
4) Indirectly: evaluation of effectiveness

Question 5

What is the “gold standard” of measure? (8)

Answer 5

Valid
Reliable
Objective
Simple
Reproducible
Quantifiable
Sensitive
Acceptable

Question 6

What is the difference between studys that are 1) descriptive and 2) analytical

Answer 6

1]. DESCRIPTIVE

Observational
Case-reports
Case-series
Cross-sectional

2]. ANALYTIC

Observational: case-control, cross-sectional
Experimental: clinical trials

Question 7

What better meta-analysis or systematic reviews?

Answer 7

meta-analysis

Question 8

List these in order of which is generally better:

1) systemic reviews
2) cohort studies
3) randomized controlled trails
4) case control studies
5) animal and lab research
6) case reports/series

Answer 8

1) systemic reviews
2) randomized controlled trails
3) cohort studies
4) case control studies
5) case reports/series
6) animal and lab research

Question 9

What is case control sutdies generally better than animal and laboratory research? (4)

Answer 9

1. stonger methodology
2. less bias
3. controls for comparison
4. fewer studies

Question 10

What are case-studies/series used for?

Answer 10

Highlighting interesting or novel cases / treatment
Recognition of new disease/outcome
Formulation of new hypotheses

Question 11

What are the disadvantages of case-studies/ case-series?

Answer 11

Cannot demonstrate valid statistical association

Lack of appropriate comparison group can obscure a relationship or suggest an association where none exists

Question 12

what is a case-report?

Answer 12

A report on a single patient or a series of patients with an outcome of interest.
No control group is required.
e.g. patient revived after no pulpse found with severe hyperthermia

Question 13

What is a cross sectional survey?

Answer 13

Observation of a defined population at a single point in time (or time interval).
Exposure and outcome are determined simultaneously.

Question 14

What is a cross sectional survey used for?

Answer 14

Measure prevalence of a disease

Look at potential risk factors or cause

Question 15

What are the weaknesses of a cross sectional survey

Answer 15

May establish association, NOT causality.
Confounders may be unequally distributed
Group sizes may be unequal
Recall bias

Question 16

describe the 2 cohorts/groups in a cohort sutdie:

Answer 16

Involves identification of two groups (cohorts) of patients, one which received the exposure of interest, and one which did not and following these cohorts forward to assess the outcome of interest.

Question 17

What is a cohort studie used for?

Answer 17

Measures the incidence of disease
Looking at causes of disease
Determining prognosis
Establishing timing and directionality of events

Question 18

What are the disadvantages of a cohort studies?

Answer 18

Controls may be difficult to identify
Exposure may be linked to hidden confounder
Blinding is difficult
For rare diseases, large sample size is often necessary or a long follow up.

Question 19

What sort of patients are used in case-control studies?

Answer 19

A study which involves identifying patients who have the outcome of interest (cases) and patients without the same outcome (controls), and looking back in time to see if they had the exposure of interest

Question 20

What are case-control studies used for?

Answer 20

Looking at potential causes of disease (suitable for rare diseases)

Question 21

What are the disadvantages of case-control studies?

Answer 21

Confounders
Selection of controls may be difficult
Recall and selection bias
Difficult to establish time relationships between exposure to the risk factor and development of the disease.

Question 22

what is the difference between a case-control study and a cohort study?

Answer 22

case control study involve looking at a number of individauls who already have the disease, cohort study looks at helahty individuals and sees if they will develop the disease (issues if a very rare disease)

Question 23

What are randomised contorlled trails used for?

Answer 23

Used for:

- Evaluating the effectiveness of an intervention.

Question 24

what are the disadvantages of randomised controlled trials?

Answer 24

High costs
Ethical issues
Participant
compliance

Question 25

What doe randomised control trails involve?

2) What is randomisation used?

Answer 25

Exposure status is assigned by the researcher, preferably by random allocation.
2) Randomisation is the best way of reducing selection bias between 2 groups of participants.

Question 26

what is a systemic review?

Answer 26

The evidence from a number of studies can be gathered together in one report which pools and analyses all available data to assess the strength of the evidence.

Question 27

Why should systemic reviews be conducted?

Answer 27

Systematic reviews can end confusion / highlight where there is not enough evidence / yield new insights by combining findings from different studies.

Question 28

What is a well known systemic review in dentistry?

Answer 28

the cochran reviews