- What type of study provides the highest level of evidence?
- Cochrane reviews which are systematic assessments of all the relevant randomised controlled trials (RCTs) which give the highest level of evidence.
4 aspects of RCT
o Randomised double blind reduces bias
o Inclusion and exclusion criteria
o Randomisation facilitates statistical analysis
o Compares one treatment over placebo to investigate any statistical significance
4 study designs
o Randomised control trials – effectiveness and efficacy of treatments
o Cohort studies – prospective study
o Case control studies – retrospective study
o Case study – one patient report
What is incidence
o Is the number of new disease cases developing over a specific period of time in a defined population,
o Incidence rate = no of new cases of disease in a period/no of individuals in population at risk
o Incidence estimates are obtained from longitudinal studies or derived from registers
What is prevalence
o Is the number of disease cases in a population at a given time
o Prevalence – no of affected individuals/total no of persons in population
o Prevalence estimates are obtained from cross-sectional studies or derived from registers which can relate to attributes to absence or presence of disease
What is SIMD
- Scottish index of multiple deprivation which is an area based index which use a range of data to decide which neighbourhoods are most deprived by ranking data zones in order of deprivation from quantile 1 – most deprived to quantile 5- 10 – least deprived
7 factors influencing deprivation
o Employment status
o Income
o Health and health care services
o Geographic access to services
o Crime
o Housing, living and working conditions
o Education, skills and training
- What are the advantages of a split mouth study design?
- Both control and intervention group are exposed to same environment.
- Each of 2 treatments are randomly assigned to either the right or left halves of the dentition on the same environment.- It removes inter-individual variability from the estimates of treatment effect
- No carry over effect for intervention or outcome
What are the disadvantages of a split mouth study design
- Patient can not be blinded
- Adds more bias into the reporting
- Incorrect reporting risk
- What is confidence intervals?
- The range of values the absolute risk difference will take in the population
- 95 out of 100; the CL will contain the true population ARD
- CL should not overlap 0 = sufficient evidence
- CL overlaps 0 = null hypothesis (insufficient evidence)
- A narrow CL is better as the larger the sample the narrower the CL
- What is a P value?
- Used to determine the significance of your results
- P value <0.05 means you reject the null hypothesis and your results are statistically significant
- What is d3t, mt and ft
- D3t = decayed deciduous Teeth
- Mt = missing teeth (XLA due to decay)
- Ft = filled teeth
- Name 3 reasons why d3mft graph shows a difference between 2 areas?
o Socioeconomic status of the area
o Ethnicity status
o Individual health board involvement
- What does the 3 in d3 mean?
- Obvious decay into dentine of the tooth using visual methods only
- At a population level, name 3 fluoride delivery methods?
o Water fluoridation
o School water fluoridation
o School milk initiative
o Fluoridated salt
- What 3 interventions are done in Scotland on a population basis?
o Smoking ban in public areas
o School food policy
o Sugar tax
o Minimum wage/national living wage
- What is PICO?
o Population:
Children with caries in primary teeth
o Intervention:
Hall technique used
o Comparison:
Compared with standard techniques
o Outcome:
Rate of failures
- What is confidence intervals and relative risk?
Confidence intervals:
The range of values the absolute risk difference will take in the population
* 95 out of 100; the CL will contain the true population ARD
* CL should not overlap 0 = sufficient evidence
* CL overlaps 0 = null hypothesis
* A narrow CL is better as the larger the sample the narrower the CL
Relative risk:
It is the ratio of incidence rate in exposed groups to incidence rates in non-exposed groups
It is a measurement of proportionate increase in disease rates of exposed groups
