The Use of Data

Question 1

Define disease

Answer 1

Symptoms, signs, diagnosis; a bio-medical perspective

Question 2

Define illness

Answer 2

Ideas, concerns, expectations; experience of patients (their perspective)

Question 3

What are the medical factors which affect the uptake of care (going to get care)?

Answer 3

New symptoms, visible symptoms, increasing severity, duration etc

Question 4

What are the non-medical factors which affect the uptake of care (going to get care)?

Answer 4

Crisis, peer pressure “wife sent me”, patient beliefs, expectations, social class, economic, psychological, environmental, cultural, ethnic, age, gender, media etc

Question 5

What is the Lays Referral concept of the uptake of care?

Answer 5

Going from family → community → traditional/cultural healing → medical system

Question 6

Where can people get info which influences their decision for uptake of care?

Answer 6

Peers, family, internet TV, health pages of newspaper or women’s mag, “What should I do? Booklet, SHOW website, Practice leaflet or website

Question 7

What are the three main aims of epidemiology?

Answer 7

1. Description
2. Explanation
3. Disease control

Question 8

Define description in epidemiology

Answer 8

To describe the amount and distribution of disease in human populations

Question 9

Define explanation in epidemiology

Answer 9

Elucidate natural history and aetiology of disease by combining data from epidemiology with data from biochem/occupational health/genetics

Question 10

Define disease control in epidemiology

Answer 10

Provide bases for preventative measures/public health practices/therapeutic strategy for disease control

Question 11

What is epidemiology used for?

Answer 11

Compares groups to detect difference in:

Aetiology
Scope for prevention
Identify high risk group

Question 12

What are the fundamental measures?

Answer 12

Clinical medicine deals with the individual patient and epidemiology deals with populations.

Rates: numerator = events and denominator = population at risk

Question 13

What is the risk part of formulating ratios in fundamental measures?

Answer 13

Everyone in the denominator must have possibility of entering the numerator, and vice versa.

Question 14

What does incidence indicate about a disease?

Answer 14

It is the number of new cases of a disease in a population in a specified period of time. Incidence tells us something about trends in causation and the aetiology of disease.

Question 15

What does prevalence indicated about a disease?

Answer 15

It is the number of people in a population with a specific disease at a single point in time or in a defined period of time.

Prevalence tells us something about the amount of disease in a population. It is useful in assessing the workload for the health service but is less useful in studying the causes of disease.

Question 16

What is relative risk?

Answer 16

Measure of the strength of an association between a suspected risk factor and the disease under study.

Question 17

What is the equation to work out relative risk?

Answer 17

(Incidence of disease in exposed group) / (incidence of disease in unexposed group)

Question 18

Give four examples of sources of epidemiological data

Answer 18

Mortality data
Hospital activity statistics
Reproductive health statistics
Cancer statistics

Question 19

What is health literacy?

Answer 19

People having the knowledge, skills, understanding and confidence to use health information, to be active partners in their care, and to navigate health and social care systems.

Question 20

Name an initiative in Scotland to improve health literacy

Answer 20

Making It Easy - A Healthy Literacy Action Plan

Question 21

What are the SIGN guidelines aims?

Answer 21

Aid in understanding and help make clinical decisions

Reduce variations in practice and provide best care no matter where Pt is

Improve healthcare across Scotland

Question 22

What are the two types of studies?

Answer 22

Descriptive and analytical

Question 23

What are descriptive studies?

Answer 23

Describe amount and distribution of disease in a given population

• No definitive conclusions, does give clue to risk factors and aetiology
• Cheap, quick, overview

Question 24

What are analytic studies?

Answer 24

Two types:
Cross sectional (disease frequency/survey): observations in a point in time 

Case Control: comparison of 2 groups

• Pt with the disease (cases)
• Pt who do not have disease (controls)

These results are compared to highlight factors on risk of disease

Question 25

How are the cases and control compared in analytical studies?

Answer 25

The average exposure to aetiological factors of each group compared to identify significant differences which indicates which factors increase (or reduce) risk of disease

Question 26

What are the result from case studies in analytical studies expressed as?

Answer 26

'Odds ratios' or 'relative risk'

Question 27

What are cohort studies?

Answer 27

Baseline data on a group without disease, who are then followed until disease developed enough to allow analysis

Question 28

How are cohort studies analysed?

Answer 28

Original group separated into subgroups according to original exposure status and these subgroup are compared to determine incidence of disease according to exposure

Question 29

What are trials?

Answer 29

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

Question 30

What is the definitive method of assessing any new treatment?

Answer 30

Randomised controlled trial

Question 31

How are randomised controlled trials carried out?

Answer 31

1. At risk groups; a study group and a control group. 2. Alteration made to the study group only 3. Data collected same way

Question 32

What is the aim of randomised controlled trials?

Answer 32

Determine whether modification of the factor (changing the exposure) alters the incidence of the disease

Question 33

How is a trial of a new treatment carried out?

Answer 33

Intervention group receive the new therapy, the control group receive the current standard therapy (or placebo) and treatment outcomes compared in two groups

Question 34

What are six factors to consider when interpreting results?

Answer 34

1. Standardisation 2. Standardised mortality ratio 3. Quality of data 4. Case definition 5. Coding and classification 6. Ascertainment

Question 35

What are standardisation factors to consider?

Answer 35

Adjusting for effects of differences of cofounding variable (i.e. age)

Question 36

What is standardised mortality ratio?

Answer 36

Standardised death rate converted to ratio, e.g. standard is 100, 120 means 20% more death than expected

Question 37

What is the factor 'case definition'?

Answer 37

Decide if an individual has the condition of interest or not; varying definition from study maker to interpreter

Question 38

What is the factor 'coding and classification'?

Answer 38

When data collected it is converted to a set of codes, to assist in data storage and analysis

Question 39

What is the factor 'ascertainment'?

Answer 39

Completeness of data. One group looking harder than another

Question 40

What is bias?

Answer 40

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

Question 41

What are four different types of bias?

Answer 41

Selection Bias Information Bias Follow up Bias Systematic Error

Question 42

Define selection bias

Answer 42

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

Question 43

Define information bias

Answer 43

Arises from systematic errors in measuring exposure or disease

Question 44

Define follow up bias

Answer 44

Arises when one group of subjects is followed up more assiduously than another

Question 45

Define systematic error

Answer 45

A form of measurement bias where there is a tendency for measurements to always fall on one side of the true value May be caused by: Instrument Wrong technique

Question 46

Define a cofounding factor

Answer 46

Associated independently with both the disease and with the exposure under investigation and so distorts the relationship between the exposure and disease. Age, sex and social class

Question 47

Name ways to deal with a cofounding factor

Answer 47

Restriction eligibility criteria Subjects in different group can be matched for likely cofounding factors Results adjusted

Question 48

What are the 9 criteria for causality

Answer 48

Temporality: exposure comes before disease [only absolute criterion] Strength of association: relative risk ratio Consistency: repeated observation of association in differing populations Specificity: single exposure leads to single disease Biological gradient: dose response relationship i.e. exposure UP = risk UP Biological plausibility: association agrees with biology of disease Coherence: association does not conflict with biology of disease Analogy: another relationship exists that can be used as a model for current Experiment: suitably controlled experiment to prove association as causal(uncommon in human populations)