Epidemiology III Flashcards
why study epidemiology
To understand burden and causes of disease
Population studies
Unnecessary to study whole population to obtain valid information about a population
Sample population must be representative of population being investigated
- Some tests only received by those who suspect they have – miss asymptomatic carriers
Evidence Based Dentistry (Medicine)
- Make sense of epidemiological studies And studies in general
- Should we believe the results
role of epidemiology
Measurement of amount and distribution of disease, and natural history of disease
Study of causes / determinants of diseases
Assess people’s risk of disease
Health care needs assessment and Service planning:
- Development of preventive programmes
Evaluation of interventions e.g.:
- caries preventive programme
- oral cancer screening
- clinical trials for drugs / treatments
3 aspects of epidemiology
descriptive
analytical
intervention - assessing intervention/programme
prevalance
Number of disease cases in a population at a given time
P - Point in time = Prevalance
Prevalence estimates obtained from cross-sectional studies or derived from registers
Can relate attributes to absence / presence of disease lead to development of a hypothesis
Used for chronic disease or high fatality e.g. diabetes
Prevalence =
Number of affected individuals (cases) /
Total number of persons in population
prevalence used for
chronic disease or high fatality e.g. diabetes
incidence
Number of new disease cases developing over a specific period of time in a defined population
Incidence estimates obtained from longitudinal studies or derived from registers
E.g. cancer (10 per 100,000 per annum), covid
Need timeframe and population size
incidence Rate =
no. of new cases of a dis. in a period /
no. of individuals in the pop. at risk
incidence needs
Need timeframe and population size
rate
prevalence estimates obtained from
cross-sectional studies or derived from registers
incidence estimates obtained from
longitudinal studies or derived from registers
distribution
How common is X?
How is X distributed in the population?
When OR time
Where place
Who person
dental caries in children
epidemiology
Epidemiology in the community
Dental Indices: DMFT / dmft
Sources of information / routine data
SHBDEP and NDIP (national dental inspection programme)
dental examples of epidemiology studies
dental caries in children
adult oral health
periodontal disease
oral cancer
oro-facial trauma
epidemiological indices
To measure disease an appropriate index is needed
Measuring for the purposes of epidemiological studies is different from recording disease for patient treatment purposes
dental epidemiology in the community - measuring caries
p1 and P7 children (5 and 11 year olds)
on a school table, public dental service
a simple assessment of the mouth of each child using a light, mirror and ball-ended probe
- specific strength of lightbulb with safety catch - standardised
DMFT / dmft
recorded on a laptop
letter sent to parent/carer - done on opt out (negative consent basis)
data analysed
properties of ideal index
clear, unambiguous, objective not subjective
ideally correspond with clinically important stages of the disease
indicate treatment need
within the ability of examiners
- train to be standardised
reproducible
not time-consuming
acceptable to patient
amenable to statistical analysis
allow comparison with other studies
DMF/dmf Index
DMF (permanent)
dmf (deciduous)
DMFT: decayed, missing & filled teeth (0-32)
DMFS index
decayed, missing & filled surfaces (0-148)
- Not incisal of upper and lower 3-3
def/dmf index
dmft: decayed, missing filled teeth (0-20)
‘e’ = indicated for exfoliated
D3MFT/ d3mft
signifies decay into dentine
D1MFT/d1mft
decay into enamel
- obvious to naked eye
when DMF index created
1937
worldwide use
reasons for teeth to be missing
caries periodontal disease trauma exfoliation (age - mixed dentition from 6) congenitally missing
issue with reporting sample no of missing teeth in 15 years
Orthodontic extractions – could have been healthy or diseased – don’t know when missing
Need to know history to decay – as only see snapshot
extensive decay
lesions into oulp
moderate decay
lesions into pulp +
clinically detectable lesions in dentine
/
clinically detectable cavities limited to enamel
+ hidden decay not seen by visual inspection
initial decay
clinically detectable enamel lesions with intact surfaces
+ hidden decay not seen by visual inspection
very early stage decay
sub clinical initial lesions in a dynamic state of progression/regreesion
obvious decay (as assessed by NDIP inspections)
lesions into pulp
clinically detectable lesions in dentine
limitations of DMF/dmf index
Teeth are extracted for reasons other than caries
Influenced by access, e.g. interproximal surface
Difficulty in differentiating fissure-sealant from restorations – underestimate caries
Influenced by past disease activity
Cannot be used for root caries
D/DMF use
indication of treatment need
proportion that is decayed of all DMF
F/DMF use
indication of treatment provision (The “Care” Index)
proportion treated
M/DMF use
indication of treatment failure
sources of routine information
UK Children’s dental health surveys (1973, 1983, 1993, 2003)
National Diet and Nutrition Surveys
BASCD – British Association for the Study of Community Dentistry) surveys - UK
SHBDEP – Scottish Health Boards’ Dental Epidemiology Programme – Scotland (old)
NDIP – National Dental Inspection Programme: Scotland. (now)
WHO – World Health Organisation: Oral Health Country/Area Profile Programme
http: //www.scottishdental.org
http: //www.whocollab.od.mah.se/
detailed NDIP
epidemiology
high level planning / evaluation of interventions
dmf/ DMF
sample 20%
basic NDIP
monitoring / targeting interventions
informing parents / children oral health status and need for dental services / basic feedback
everyone receives
adult oral health sources of information
Adult Dental Health Survey (ADHS)
recent trends and future projections
generic information source for adult health
General surveys : Scottish Health Survey
Specific health related surveys
dental information source for adult health
UK Adult Dental Health Survey
Scottish Adult Dental Health Survey
service related information source
public health scotland
- Databases, Journals, Publications - Regional / Local, National, International.
adult dental health survey measures
Total tooth loss, number of teeth and function
Condition of natural teeth, restorative treatment and supporting structures
Social and behavioural characteristics and oral health
Trends in tooth loss and the condition of natural teeth
Dental attitudes and reported behaviour
Reports by country
tooth mortality
Tooth loss has been considered a form of “dental mortality”
It is a crude (but still a good) measure of general oral health
- either as partially dentate (number of natural teeth)
- or as total tooth loss (edentulous).
black and minority adult ethnic groups are less likely to experience … compared to white adults
edentulous
toothache
(after controlling for SEP)
periodontal disease indices (3)
Plaque indices, e.g.
- Debris Index (Green & Vermillion, 1960)
- Plaque Index (Silness & Loe, 1964)
Gingivitis indices, e.g.
- Modified Gingival Index (Loe, 1967)
- Lobene Index (Lobene, 1986)
Periodontitis indices, e.g.
- CPITN / BPE
CPITN measurement
WHO Community Periodontal Index of Treatment Need
Established mid 1980s
Internationally accepted method of estimating levels of periodontal conditions in populations
Relatively simple and quick to perform
