Tutorial 2: Use of Data Flashcards
What percentage of people consult their general practice about their complaints
20%
How many of those patients are referred on to hospital investigation or care
3%
Define Disease
Defined as a condition that is diagnosed by a physician or other medical expert. Based on symptoms and signs
Define Illness
Illness is defined as the ill health the person identifies themselves with, often based on self reported mental or physical symptoms
Name medical factors that affect the uptake of care
New symptoms
Visible symptoms
Increasing severity
Duration
Name non-medical factors that affect the uptake of care
Crisis Peer pressure Patient beliefs Expectations Social class Economic Psychological Environmental Cultural Ethnicity Age Gender Media
What are the 3 main aims of epidemiology
Description
Explanation
Disease control
What is the relative risk
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
Name sources of epidemiological data
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
What is the use of the SIGN guidelines
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
Define descriptive studies
Descriptive studies attempt to describe the amount and distribution of a disease in a given population
Define cross-sectional studies
Observations are made at a single point in time variables involved are disease frequency, survey, prevalence study
Define case control study
Two groups of people are compared. The group of individuals who have the disease and a control group
Define cohort studies
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.
What are Trials
Trials are experiments used to test ideas about aetiology or to evaluate interventions
When interpreting results what factors must be considered
Standardisation
Standardised Mortality Ratio
Quality of Data
Case Definition
Coding and Classification
Ascertainment
Define Standardisation
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
Define Standardised Mortality Ratio
It is simply a standardised death rate converted into a ratio for easy comparison.
What is Bias
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.
Name the types of bias
Selection Bias Information Bias Follow up Bias Systematic Error Publication bias
Define Selection Bias
Occurs when the study sample is not truly representative of the whole study population about which conclusions are to be drawn.
What is Information Bias
Arises from systematic errors in measuring exposure or disease
What is Follow up Bias
Arises when one group of subjects is followed up more assiduously than another to measure disease incidence or other relevant outcome.
What is Systematic Error
A form of measurement bias where there is a tendency for measurements to always fall on one side of the true value
Publication Bias
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)
What are cofounding Factors
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.
Describe the Criteria for Causality
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.
