Principles of Epidemiology Flashcards
What is epidemiology?
Orderly study of diseases and conditions where the group and not the individual is of interest
Name 2 ways which the information on epidemiology is used
- Understand changes over time
2. Plan health services
What are 4 reasons to measuring disease at individual level in terms of providing information?
- To aid diagnosis
- To aid treatment
- Measure individual treatment need
- Measure individual treatment outcomes
What are 3 reasons to measuring disease at population level in terms of providing information?
- Record prevalence of diseases and conditions
- Provide indication of population treatment need
- Evaluate effectiveness of health programmes
What is a count data?
Number of people in an area affected at one point in time
Describe 3 reasons a denominator is important in measuring disease in population
- The number at risk is unknown without a denominator
- Changes over time cannot be identified without a denominator
- Areas cannot be compared without a denominator
How is epidemiological data usually reported?
Rates or proportions
How is a study population usually defined?
By sharing a common characteristics e.g. age or sex
What are the 3 key features of a study sample?
- Representative of population
- Sufficient size
- Sufficient distribution
What is point prevalence?
Proportion of people with a disease at any given point
What is period prevalence?
Proportion of people with a disease over a period of time
What does prevalence show?
The amount of people affected out of the total amount who could be
What is incidence?
Number of new cases of a disease that occur in a specified time period divided by population at risk
What is severity?
How severe a condition is
What is standardized data?
A technique used to account for the effect of confounding factors in populations
What does SMR stand for?
Standardized mortality ratio
How is SMR measured?
Observed number of deaths per year / Expected number of deaths per year
Describe 3 features of study design
- Objective
- Protocol
- Ethical and other approvals
What are 2 types of descriptive epidemiology study designs?
- Cross-sectional (one point in time)
2. Longitudinal (following same people over time)
What are 2 types of analytical epidemiology study designs?
- Observational (not trying to change course of disease)
2. Experimental (interventional)
What does a quantitative method of epidemiology study rely on?
An underlying measurable truth that is generalizable
Name 5 types of qualitative methods of epidemiology study
- Recognise and seek individual perspectives
- Exploratory
- Interviews
- Focus groups
- Observations of people
What is descriptive epidemiology?
Describes patterns of disease, risk factors and determinants of health in a population or sub-group
Name 2 types of data which are available before commencing a new study
- Routinely collected data
2. Cross-sectional studies
What is the function of observational studies?
Evaluate prevalence of diseases and examine associations between risk factors and disease occurrence
What are case control studies?
Retrospective recording, matching people who have condition or risk factor with controls who do not, and comparing the outcome
What is interventional study?
Intervening to evaluate benefit e.g. new drugs
Describe the evidence hierarchy of epidemiological study designs, in order of increasing weight of evidence
- Case reports (descriptive)
- Ecological studies (descriptive)
- Cross-sectional studies (analytical)
- Case-control studies (analytical)
- Retrospective / Prospective cohort studies (analytical)
- Randomized clinical studies (analytical)
Name 9 properties of an ideal dental index
- Simple
- Objective
- Clear-cut categories
- Valid
- Reliable
- Reproducible
- Quantifiable
- Sensitive
- Acceptable
Describe “simple” as an ideal property of a dental index
Simple to understand, learn and administer
Describe “objective” as an ideal property of a dental index
Reduce examiners subjective opinion and avoid different examiners recording different levels
Describe “clear-cut categories” as an ideal property of a dental index
Ideally relate to distinct stages of clinical condition
Describe “valid” as an ideal property of a dental index
Must measure what the study is intended to measure e.g. discriminate between white spots for caries and developmental hypoplasia
Describe “reliable” as an ideal property of a dental index
Each time the index is used it should record the same outcome
Describe “reproducable” as an ideal property of a dental index
Should record the same outcome when, either, two different examiners measure the same condition or the same examiner measures the condition on two different occassions
Describe “quantifiable” as an ideal property of a dental index
Allows output for statistical purposes
Describe “sensitive” as an ideal property of a dental index
Detect and record small changes in disease level
Describe “acceptable” as an ideal property of a dental index
To subject and examiner e.g. not painful
What is DMFT?
A common dental index which stands for “Decayed, Missing and Filled Teeth”
Describe 4 features of the DMFT
- Measurement of caries experience
- A count (each condition has equal weight)
- Missing component is extraction due to caries only
- Simple index, reliable and relatively easy to use
Describe 3 draw backs of DMFT
- Does not discriminate between current and past disease
- Does not provide measure of teeth present
- Limited ability to assess treatment need
What 5 clinical features do periodontal indices measure?
- Plaque
- Calculus
- Gingival inflammation
- Pocketing
- Attachment loss
Name a common periodontal index
CPITN (Community Periodontal Index of Treatment Need)
Name 3 levels of periodontal disease
- Periodontally healthy
- Periodontally healthy but with calculus or bleeding
- Some periodontal disease present
What is the critical value in whether periodontal disease is present in terms of pocketing?
4mm
Name a common orthodontal index
IOTN (Index of Orthodontic Treatment Need)
Name 2 parts of the IOTN
- DHC (Dental Health Component)
2. AC (Aesthetic Component)
In the modified version of the IOTN, what are the 5 aspects of the AC?
MOCDO (missing teeth, overjet, crossbite, displacements and overbite)
What does the DDE index stand for?
Developmental Defects of Enamel
What does DDE measure?
Classifies defects that develop pre-eruption and represent disturbances in mineralisation
Name 3 reasons why disturbances in mineralisation can occur
- Excess fluoride ingestion
- Traumatic injury
- Hypoplasia
Name an index used to measure fluorosis
Dean’s Index
