FoPC Year 2 Tutorial 2 - The Use of Data Flashcards
1
Q
what proportion of people consult their GP about their health complaints
A
20%
2
Q
what proportion of patients visiting their GP are referred onto secondary care
A
3%
3
Q
define disease
A
symptoms, signs ⇒ diagnosis
(bio-medical perspective)
4
Q
define illness
A
ideas, concerns, expectations – experience
patients perspective
5
Q
what proportion of GP appointments involve no disease
A
up to 50%
6
Q
list several medical and non-medical factors which may influence an individuals desire to seek medical attention
A
Medical factors - new/visible symptoms, increasing severity, duration (e.g long)
Non medical factors – crisis, peer pressure “wife sent me”, patient beliefs, lay refferal, expectations, social class, economic, psychological, environmental, cultural, ethnic, age, gender, GP practice leaflet, NHS website, media: internet, TV, newspaper
7
Q
who seeks medical attention more often - males or females?
A
females
8
Q
give 3 reasons a patient that feels well may not want to accept treatment
A
- believe themselves to be healthy.
- is physically fit.
- proud not to be using tablets.
9
Q
define epidemiology
A
study of how often diseases occur in different groups of people and why
10
Q
what are the 3 main aims of epidemiology
A
- description
- explanation
- disease control
11
Q
regarding epidemiology, define description
A
to describe the amount and distribution of disease in human populations
12
Q
regarding epidemiology, define explanation
A
to elucidate (find out) the natural history and identify aetiological factors
usually by combining epidemiological data with data from other disciplines such as biochemistry, occupational health and genetics
13
Q
regarding epidemiology, define disease control
A
data can provide basis for
- preventive measures
- (develop new/modify) public health practices
- therapeutic strategies
to be developed, implemented, monitored and evaluated to help control disease.
14
Q
epidemiology compares groups (study populations) in order to detect differences.
describe 3 things that may be detected/discovered
A
- aetiological clues
- scope (capacity) for prevention
- identification of high risk/priority groups in society
15
Q
in epidemiology, give some examples of different study populations (based on: )
A
the study population may be defined by:
- age
- sex
- location
(or even be the same group over time)
we then compare how often an event appears in one group with another
16
Q
data in epidemiology is converted into ratios - what does the numerator consist of?
A
number of events e.g death / [population at risk]
17
Q
data in epidemiology is converted into ratios - what does the denominator consist of?
A
[number of events] / population at risk
18
Q
minor illnesses (e.g. a cold) typically have a
(high/low) ______ incidence
(high/low) ______ prevalence
A
high incidence
low prevalence
19
Q
chronic illnesses (e.g. diabetes) typically have a
(high/low) ______ incidence
(high/low) ______ prevalence
A
low incidence
high prevalence
20
Q
incidence is useful for investigating what aspect of a disease?
A
aetiology of disease
21
Q
what does the prevalence of a disease tell us?
A
prevalence tells us something about the amount of disease in a population
22
Q
define relative risk
A
Relative risk (RR) =
incidence of disease in exposed group
/
incidence of disease in unexposed group
23
Q
what is relative risk (RR) a measure of?
A
the strength of association between a suspected risk factor and the disease
24
Q
give 10 sources of epidemiological data
A
- mortality data
- hospital activity statistics
- reproductive health statistics
- cancer statistics
- accident statistics
- general practice morbidity
- health and household surveys
- social security statistics
- drug misuse databases
- expenditure data from NHS
25
# define health literacy
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.
26
why is health literacy relevant?
health literacy is being increasingly recognised as a significant **health concern** around the world
27
describe descriptive studies
descriptive studies attempt to describe the **amount** and **distribution** of a disease in a given **population**
28
describe the advantages and limitations of descriptive studies
**_limitation_**
1. does not provide **definitive conclusions** about disease **causation**,
**_advantages_**
1. may give clues to possible **risk factors and candidate aetiologies**.
2. usually **cheap, quick** and give a valuable initial **overview** of a problem.
29
what is a cross-sectional study?
in cross-sectional studies, **observations** are made at a **_single point_ in time**
30
what conclusions are drawn from cross-sectional studies?
**relationship** between **diseases** and other **variables** of interest in a defined population.
31
one strenght of a cross-sectional study
provide results **quickly**
32
one negative of a cross-sectional study
usually **impossible** to infer **causation**
33
what is a case control study?
two groups of people are compared:
1. **Cases** - those who have the disease of interest
2. **Controls** - those who do not
34
how are conclusions drawn from case-controlled studies (process)?
1. both groups have **exposure** to a suspected aetiological factor measured
2. amount (of disease?) is **compared** to identify **significant differences**
3. to give clues as to what **factors elevate/reduce risk** of disease being studied
35
what are the results in a case controlled study expressed as?
relative risk (RR)
36
what is a cohort study?
1. **_baseline data_ on exposure** collected from a group who do ***not*** have the disease under study
2. group is then **_followed_** through time until a sufficient **number** have **developed** the disease
3. original group is separated into **subgroups** according to original **exposure status** and compared to determine i**_ncidence of disease according to exposure._**
cohort studies allow the **calculation** of **cumulative incidence,** allowing for differences in follow up time.
37
what are trials?
trials are **experiments** used to test ideas about **aetiology** or to **evaluate interventions**
38
what is the definitive method of assessing any new treatment in medicine?
the “randomised controlled trial”
39
how is a trial assessing aetiology conducted?
two groups at **risk** of developing a disease are assembled
1. **_intervention group_** - alteration made (eg suspected causative factor removed)
2. **_control group -_** no alteration is made
**data** on subsequent **outcomes** (eg disease incidence) are collected from both groups, and the **relative risk i**s calculated.
40
how is a trial assessing a new treatment conducted?
1. **intervention group** receive _new therapy_
2. **control group** receive current _standard therapy_ *(or placebo)*
**⇒ treatment outcomes** (eg reduction in symptoms) **compared** in both groups
41
what is meant by standardisation?
a set of **techniques** used to **remove** (or adjust for) the **effects** of **differences** in age, gender or other confounding variables, when comparing two or more populations.
42
what is the standardised mortality ratio (SMR)?
a special kind of **standardisation**
it is simply a **_standardised death rate_** converted into a ratio for easy **comparison**
the figure for a standard reference population (eg, Scotland) is taken to be 100 and the standardised death rates for the comparison (study) populations (eg, Grampian) are expressed as a proportion of 100. A figure below one hundred means fewer than expected deaths, and above 100 means more. For example, an SMR of 120 means that 20% more deaths occurred than expected in the study population, allowing for differences in the age and sex structure of the standard and study populations and an SMR of 83 means 17% fewer deaths occurred.
43
describe why the quality of data is an important factor to consider in interpreting results
must ensure data is **trustworthy**.
44
explain what 'case defintion' means
the purpose of it is to **decide** whether an individual has the **condition** of interest **or not**.
It is important because not all doctors or investigators **mean** the same thing when they use **medical terms**. **Differences in incidence** of disease over time or in different populations may be **artefact**, due to differences in **case definition**, rather than differences in **true incidence.**
**Artefact definition:** *something observed in a scientific investigation or experiment that is not naturally present but occurs as a result of the preparative or investigative procedure.*
45
describe 'coding and classification'
when data is being collected routinely (eg death certificates), it is normal to **convert disease information** to a set of **codes**, to assist in **data storage and analysis.**
**rules** are drawn up to dictate how clinical information is converted to a code. If these rules **change**, it sometimes appears that a disease has become **more common, or less common**, when in fact it has just been coded under a **new heading**.
46
describe 'ascertainment' aka ascertainment bias
Is the data **complete** - are any subjects missing?
If researchers in one country **look harder** for cases of a given disease than researchers in any other, it might not be surprising that they come up with **higher incidence rates.**
Ascertainment bias arises when data for a study or analysis is collected such that **some members** of the intended population are **less/more likely to be included than others**
47
define bias
any **trend** in the **_collection, analysis, interpretation, publication or review of data_** that can lead to conclusions that are **systematically different** from the truth
48
name 4 types of bias
1. Selection Bias
2. Information Bias
3. Follow up Bias
4. Systematic Error
49
describe selection bias
_Selection bias_
Occurs when the **study sample is not truly representative** of the whole study population about which **conclusions** are to be drawn.
For example, in a randomised controlled trial of a new drug, subjects should be allocated to the intervention (study) group and control group using a **random method**. If certain types of people (eg, older, more ill) were **deliberately allocated t**o one of these groups then the results of the trial would **reflect** these differences, **not just** the **effect** of the drug.
50
describe information bias
_Information bias_
arises from **systematic errors in measuring exposure or disease.** For example, in a case control study, a researcher who was **aware** of whether the patient being interviewed was a '**case**' or a '**control**' might encourage cases more than controls to think hard about past exposures to the factors of interest. Any differences in exposure would then reflect the **enthusiasm** of the researcher as well as any true difference in exposure between the two groups.
51
describe follow up bias
arises when **one group of subjects is followed up more diligently than another** to measure disease incidence or other relevant outcome.
For example, in cohort studies, subjects sometimes **move address** or fail to reply to questionnaires sent out by the researchers. If greater attempts are made to trace these missing subjects from the group with greater initial exposure to a factor of interest than from the group with less exposure, the resulting relative risk would be based on a (relative) underestimate of the incidence in the less exposed group compared with the more exposed group.
52
describe systematic error
**tendency for measurements to always fall on one side of the true value.**
It may be because the **instrument** (eg blood pressure machine) is **calibrated** wrongly, or because of the way a person **uses** an instrument. This problem may occur with interviews, questionnaires etc, as well as with medical instruments.
53
what is a confounding factor?
factor **associated** independently with both the **disease** *and* with the **exposure** under investigation
⇒ **distorts** relationship between exposure and disease.
(in some cases the confounding factor may be the true causal factor, and not the exposure that is under consideration)
54
give 3 examples of confounding factors
1. age
2. sex
3. social class
55
describe 5 ways around confounding factors
* **randomisation**
* **restriction** of eligibility criteria to **only certain kinds** of study subjects
* subjects in different groups can be **matched** for likely **confounding factors**.
* results can be **stratified** _(arranged)_ according to confounding factors.
* results can be **adjusted** (using _multivariate analysis_ techniques) to take account of suspected confounding factors.
56
describe 9 factors in the criteria for causality
## Footnote
(It is difficult to prove causation between an exposure and disease. Often the best that can be achieved is to demonstrate a weight of evidence in favour of a causal relationship. A number of criteria have been devised to help investigators assess the available evidence, known as the criteria for causality)
1. **_Strength_** of **_association_**: the larger the association, the more likely that it is causal.
2. **_Consistency_**: Consistent findings observed by different persons in different places with different samples strengthens the likelihood of an effect.
3. **_Specificity :_** Causation is likely if there is a very specific population at a specific site and disease with no other likely explanation.
4. **_Temporality_**: The effect has to occur _after_ the cause
5. **_Biological gradient:_** Greater exposure should generally lead to greater incidence of the effect
6. **_Biological plausibility:_** A plausible _mechanism_ between cause and effect is helpful
7. **_Coherence:_** Coherence between epidemiological and laboratory findings increases the likelihood of an effect.
8. **_Analogy_** : The effect of similar factors may be considered.
9. **_Experiment_:** experimental evidence
57
list the 3 intended aims of sign guidelines
1. **Help healthcare professionals** + **patients understand medical evidence** and **use** it to make **decisions** about healthcare.
2. **Reduce unwarranted variations in practice** + make sure patients get **best care** available, no matter where they live
3. **Improve healthcare** across Scotland by focusing on patient-important outcomes
58
What does SIGN stand for and what do they do
* The **Scottish Intercollegiate Guidelines Network (**SIGN)
* Develop *evidence based* **clinical practice guidelines** for the **_NHS in Scotland._**
