Epidemiology

Question 1

What is prevalence?

Answer 1

• number of disease cases in a population at a given time

Question 2

What is incidence?

Answer 2

• number of new disease cases developing over a specific period of time in a defined population

Question 3

How is dental epidemiology measured/

Answer 3

• DMFT
  
  • Decayed, Missing and Filled Teeth

Question 4

What are epidemiological indices?

Answer 4

• used to measure disease
  
  • approximate index needed

Question 5

What are the properties of an ideal index?

Answer 5

• clear, unambiguous, objective
• correspond with clinically important disease stages
• indicate treatment need
• within ability of examiners
• reproducible
• not time-consuming
• acceptable to patient
• amenable to statistical analysis
• allow comparison with other studies

Question 6

What are the limitations of the DMF index?

Answer 6

• teeth extracted for reasons other than caries
• influenced by access
  
  • inter proximal surfaces
• difficulty differentiating fissure-sealant from restorations
  
  • underestimate caries
• influenced by past disease activity
• cannot be used for root caries

Question 7

How are the different components of the DMFT index used

Answer 7

• D
  
  • indication of treatment needed
• F
  
  • indication of treatment provision
• M
  
  • indication of treatment failure

Question 8

What is NDIP?

Answer 8

• National Dental Inspection Programme
• detailled
  
  • epidemiology
    - high level planning
    - evaluation of interventions
• basic
  
  • monitoring
    - targeting interventions
    - informing parents/children oral health status
    - need for dental services

Question 9

What is a risk factor in epidemiology?

Answer 9

• environmental, behavioural or biological factor confirmed by temporal sequence, usually increasing the probability of a disease occurring and if absent or removed, reduces the probability

Question 10

What are the Bradford Hill criteria for a causal association?

Answer 10

• strength of association
• dose response
• change in risk factor results in reduction
• time sequence
• consistency
• specificity (defined exposures)
• biological plausibility
• experimental preventive trials

Question 11

What are confounding variables?

Answer 11

• extraneous variable which has been left uncrontrolled

Question 12

What is risk factor hypothesis?

Answer 12

• suggestion that exposure to particular agent may cause development of particular disease if susceptible individual exposed to agent

                  OR

• suggestion that possession of certain characteristics may make disease outcome more likely if exposed to certain agents

Question 13

What are the three common indices of risk?

Answer 13

• absolute
  
  • basic measure
  • incidence rate of disease amongst those exposed to agent
  • assumes risk incurred by people not exposed to agent
• attributable
  
  • different incidence rates in exposed and non-exposed
  • represents risk attributable to factor being investigated
• relative
  - retain of incidence rate in exposed group to incidence rate in non-exposed group
  
  • measurement of proportional increase in disease rates of expose group
  • allows for frequency of disease amongst people non exposed

Question 14

What are cohort studies?

Answer 14

• prospective studies
• recruitment of group that do not manifest disease
  
  • assess risk factors
• individuals observer over period of time
  
  • measure frequency of disease occurrence
    - people exposed to risk factor
    - people not exposed to risk factor

Question 15

What are case-control studies?

Answer 15

• retrospective studies
• compare individuals with disease to those without
• trace back to assess risk factors
  
  • past exposure to suspected harmful agent
• less robust than cohort studies
  
  • used for preliminary investigated on hypothesis
  • followed by cohort