Evidence Based Dentistry

Question 1

what is a risk?

Answer 1

number of events of interest over the total number of observations

Question 2

what is odds?

Answer 2

number of events of interest over the number without the event

Question 3

what are the questions to ask when interpreting risk?

Answer 3

risk of what? how big is the risk? does the risk information reasonably apply to me or my patient? how does this risk compare with other risks?

Question 4

what are the questions to ask when you see messages about risk reduction?

Answer 4

reduced risk of what? how big is the risk of reduction? does the risk reduction information reasonably apply to me? any downsides? is the benefit worth the downsides?

Question 5

what are the starting and modified risks?

Answer 5

the chances of the outcome in the untreated and treated groups

Question 6

what is relative risk reduction?

Answer 6

makes even small risk reductions sound big

Question 7

what is the absolute risk difference?

Answer 7

difference in risk between groups

Question 8

what is NNT

Answer 8

number of patients you would need to treat to prevent one patient from developing the disease/condition/outcome

Question 9

what does a confidence interval which overlaps the vale of no difference indicate?

Answer 9

insufficient evidence for a difference between the treatment and control group in the population

Question 10

for a difference between two values what is the value of no difference?

Answer 10

0

Question 11

for a ratio between two values what is the value of no difference?

Answer 11

1

Question 12

what are the 3 main types of study designs in human research?

Answer 12

observational uncontrolled studies, controlled studies, randomised controlled trials

Question 13

what are the different types of studies?

Answer 13

case series/case reports, ecological studies, cross-sectional surveys, case-control studies, cohort studies, randomised controlled trials, systematic reviews and meta analyses

Question 14

what is a case report/case series

Answer 14

a report on a single patient or series of patients with an outcome of interest, used for hypothesis generation

Question 15

what is a cross-sectional study?

Answer 15

the observation of a defined population at a single point in time (or time interval), used for estimating prevalence of a disease

Question 16

what is case control study?

Answer 16

the study of people with a disease and a suitable control group of people without the disease - looks back in time at exposure to a particular risk factor in both groups, used for looking at potential causes of disease

Question 17

what is a cohort study?

Answer 17

establish a group of individuals in population, measure exposures and follow up after a period of time, used for estimating incidence of disease and investigating causes of disease

Question 18

what is the gold standard study design?

Answer 18

randomised controlled trials

Question 19

what does a randomised controlled trial provide?

Answer 19

strongest evidence on effectiveness of treatments

Question 20

what are the 4 design elements of an RCT?

Answer 20

specification of participants, control/comparison groups, randomisation, blinding/masking

Question 21

what are the inclusion/exclusion criteria to consider with an RCT?

Answer 21

age, disease severity, unambiguous, exact definitions

Question 22

why is randomisation important?

Answer 22

to minimise bias of older patients/more severe disease patients

Question 23

how do you randomise patients into their groups?

Answer 23

assign participant to one of the two groups, performed by a computer

Question 24

what is the advantage of randomisation?

Answer 24

random allocation ensures each individual entered into trial has equal chance of being allocated to any treatment arm

Question 25

which groups of people are not allowed to know which group a patient has been placed in with an RCT?

Answer 25

participant, administrator of treatment, assessor of outcome, data analyst

Question 26

what is the advantage of an RCT?

Answer 26

provide strongest and most direct epidemiologic evidence for causality

Question 27

what are the disadvantages of RCTs?

Answer 27

more difficult to design and conduct than observational studies, still some risk of bias and generalizability often limited , not suitable for all research questions