Tutorial 2: Use of Data

Question 1

What percentage of people consult their general practice about their complaints

Answer 1

20%

Question 2

How many of those patients are referred on to hospital investigation or care

Answer 2

3%

Question 3

Define Disease

Answer 3

Defined as a condition that is diagnosed by a physician or other medical expert. Based on symptoms and signs

Question 4

Define Illness

Answer 4

Illness is defined as the ill health the person identifies themselves with, often based on self reported mental or physical symptoms

Question 5

Name medical factors that affect the uptake of care

Answer 5

New symptoms
Visible symptoms
Increasing severity
Duration

Question 6

Name non-medical factors that affect the uptake of care

Answer 6

Crisis
Peer pressure
Patient beliefs
Expectations
Social class
Economic 
Psychological
Environmental
Cultural 
Ethnicity
Age
Gender
Media

Question 7

What are the 3 main aims of epidemiology

Answer 7

Description
Explanation
Disease control

Question 8

What is the relative risk

Answer 8

This is the measure of the strength of an association between risk factor and the disease under study
Relative risk (RR) = incidence of disease in exposed group
/incidence of disease in unexposed group

Question 9

Name sources of epidemiological data

Answer 9

Mortality data
Hospital and clinical activity statistics
Reproductive health statistics
Infectious disease statistics
Cancer statistics
Accident statistics
General practice morbidity statistics
Health and household surveys
Labour force surveys
Social security statistics
Drug misuse databases
Expenditure data from NHS

Question 10

What is the use of the SIGN guidelines

Answer 10

Help health and social care professionals and patients understand medical evidence and use it to make decisions about healthcare
Reduce unwarranted variations in practice and make sure patients get the best care available, no matter where they live

Question 11

Define descriptive studies

Answer 11

Descriptive studies attempt to describe the amount and distribution of a disease in a given population

Question 12

Define cross-sectional studies

Answer 12

Observations are made at a single point in time variables involved are disease frequency, survey, prevalence study

Question 13

Define case control study

Answer 13

Two groups of people are compared. The group of individuals who have the disease and a control group

Question 14

Define cohort studies

Answer 14

In cohort studies, baseline data on exposure are collected from a group of people who do not have the disease under study.

The group is then followed through time until a sufficient number have developed the disease to allow analysis.

Question 15

What are Trials

Answer 15

Trials are experiments used to test ideas about aetiology or to evaluate interventions

Question 16

When interpreting results what factors must be considered

Answer 16

Standardisation

Standardised Mortality Ratio

Quality of Data

Case Definition

Coding and Classification

Ascertainment

Question 17

Define Standardisation

Answer 17

A set of techniques used to remove (or adjust for) the effects of differences in age or other confounding variables, when comparing two or more populations

Question 18

Define Standardised Mortality Ratio

Answer 18

It is simply a standardised death rate converted into a ratio for easy comparison.

Question 19

What is Bias

Answer 19

Bias is any trend in the collection, analysis, interpretation, publication or review of data that can lead to conclusions that are systematically different from the truth.

Question 20

Name the types of bias

Answer 20

Selection Bias
Information Bias
Follow up Bias
Systematic Error
Publication bias

Question 21

Define Selection Bias

Answer 21

Occurs when the study sample is not truly representative of the whole study population about which conclusions are to be drawn.

Question 22

What is Information Bias

Answer 22

Arises from systematic errors in measuring exposure or disease

Question 23

What is Follow up Bias

Answer 23

Arises when one group of subjects is followed up more assiduously than another to measure disease incidence or other relevant outcome.

Question 24

What is Systematic Error

Answer 24

A form of measurement bias where there is a tendency for measurements to always fall on one side of the true value

Question 25

Publication Bias

Answer 25

Occurs where positive results have a greater chance of being published (even if the quality of the study is poorer than a similar study showing negative results)

Question 26

What are cofounding Factors

Answer 26

one which is associated independently with both the disease and with the exposure under investigation and so distorts the relationship between the exposure and disease. For example, if you are researching whether lack of exercise leads to weight gain, lack of exercise is your independent variable and weight gain is your dependent variable. Confounding variables are any other variable that also has an effect on your dependent variable.

Question 27

Describe the Criteria for Causality

Answer 27

Strength of association- As measured by relative risk or odds ratio.
Consistency-Repeated observation of an association in different populations under different circumstances.
Specificity-A single exposure leading to a single disease.
Temporality-The exposure comes before the disease.
Biological gradient-Dose-response relationship. As the exposure increases so does the risk of disease.
Biological plausibility
The association agrees with what is known about the biology of the disease.
Coherence-The association does not conflict with what is known about the biology of the disease.
Analogy
Another exposure-disease relationship exists which can act as a model for the one under investigation.
For example, it is known that certain drugs can cross the placenta and cause birth defects
- it might be possible for viruses to do the same.
Experiment
A suitably controlled experiment to prove the association as causal - very uncommon in human populations.