Epidemiology Flashcards
What is epidemiology?
- The study of populations in order to determine the frequency and distribution of disease
- (it helps in identifying risk factors for disease and determining optimal treatment approaches to clinical practice and preventative medicine)
What are the major roles of epidemiology? (7 points)
- Monitor infectious and non-infectious diseases
- Study natural history of diseases
- Investigation of disease risk factors
- Health care needs assessment
- Development of preventative programmes
- Evaluation of interventions
- Health service planning
One major role of epidemiology is to study the natural history of diseases. What are the groupings of these? (4 points)
- Self-limiting
- Chronic
- Fatal
- Unknown
One major role of epidemiology is for health needs assessment. This is what care services are required by particular groups. What is this dependent on?
- The health status and demographics of the population
One major role of epidemiology is the development of preventative programmes. What is this based on?
Knowing risk factors of diseases and attempting to prevent exposure to these factors
What are the 3 main types of epidemiological study?
- Descriptive (observational)
- Analytic (observational - case control or cohort)
- Intervention/experimental
What are 2 terms that are a measure of disease frequency?
- Prevalence
- Incidence
What is meant by the term ‘prevalence’?
- A measurement of ALL individuals affected by the disease within a particular period of time or point in time
- It is the number of existing cases in a population
- Number of affected individuals (cases) divided by the total number of persons in the population
- Prevalence estimates are obtained from cross-sectional studies or derived from registers
- It is used as an estimate of how common a condition is within a population over a certain period of time or point in time
What is meant by the term ‘incidence’?
- A measurement of the number of NEW individuals who contract a disease during a particular period of time
- Number of new cases or events during a specific period of time in a defined population
- Incidence estimates obtained from longitudinal studies or derived from registers
Why might a chronic incurable disease like diabetes have a low incidence but a high prevalence?
Because the prevalence in the cumulative sum of the past year incidence rates
Why might a short duration curable condition such as the common cold have a high incidence but a low prevalence?
Because many people get a cold each year, but few people actually have a cold at any given time (so prevalence is low)
In descriptive studies the main variables broadly fall into 3 categories. What are these categories?
- Time
- Place
- Person
OR
- Where
- When
- Who
When sampling a population for a survey, is it necessary to study the whole population to obtain valid information about that population?
- No
What are the advantages of sampling as a survey method? (4 points)
- Reduces no. of individuals to be sampled
- Reduces cost
- Higher response rate
- Higher quality of information collected
Why must a sample be representative of the population being investigated?
- As this aims to avoid bias
What are 5 sampling techniques?
- Simple random sample
- Systematic sample
- Stratified sample
- Cluster sample
- Multi-stage sampling
What is the ‘simple random sampling’ technique?
For example - use of a table of random numbers
What is the ‘systematic sample’ technique?
- individuals selected at regular intervals from a population list
What is the ‘Stratified sample’ technique?
- Ensure small sub-groups are adequately represented
What is the ‘cluster sample’ technique?
- Use of groups as sampling units e.g. school classes
What is the ‘multi-stage sampling’ technique?
- Combines all of the other sampling techniques (simple random sample, systematic sample, stratified sample, cluster sample)
What are possible forms of error or bias in survey methodology? (5 points)
- Sampling bias/selection bias
- Response bias/information bias
- Measurement error
- Observer variation (intra- or inter-)
- Loss to follow up
What are the properties of an ideal index? (9 points)
- Clear, unambiguous, non subjective
- Ideally correspond with clinically important stages of the disease
- Indicate treatment need
- Within the ability of examiners
- Reproducible
- Not time-consuming
- Acceptable to patient
- Amendable to statistical analysis
- Allow comparison with other studies
What are the limitations of the DMF (decayed, missing and filled teeth) index? (6 points)
- Teeth extracted for reasons other than caries
- Influenced by access e.g. interproximal surface
- Difficulty in differentiating fissure-sealant from restorations - underestimate caries
- Influenced y past disease activity
- Threshold criteria of disease can vary (must specify)
- Cannot be used for root caries
