PHEBP Definitions

Question 1

epidemiology

Answer 1

the study of the distribution and determinants of health-related states or events in populations (and the application of this to control population health)

Question 2

public health

Answer 2

the art and science of preventing disease, prolonging life and promoting health through the organised efforts of society

Question 3

exposure

Answer 3

lack of vitamin D, poor diet (any factor associated with an outcome of interest)

Question 4

outcome

Answer 4

health outcome like getting diabetes

Question 5

risk

Answer 5

intuitive understanding that it is something that increases our likelihood of harm

Question 6

ecological study

Answer 6

a study completed at group/population level that measures an exposure/outcome
- At least one comparison group is present, with disease occurrence compared between groups
- it is a type of observational study

Question 7

cross sectional study

Answer 7

focuses on all persons in a defined population and aims to determine their disease status at that point in time
- examines the relationship between exposure and the health outcome of interest
- a type of observational study

Question 8

cohort studies

Answer 8

exposed and non-exposed individuals in a population are studied for the presence of a fixed or modifiable exposure (thought to be the cause of a disease), prior to the onset of the disease
- a type of observational study
- incidence in exposed is compared to incidence in non-exposed

Question 9

case-control studies

Answer 9

an observational study that determines potential risk factors in individuals with condition
- diseased (cases) and non-diseased (controls) subjects are compared
- data concerning past exposure and potential risk factors is collected retrospectively

Question 10

confounding

Answer 10

when the obeserved effect of an exposure on an outcome is distorted by some other variable (confounder)
the confounder is related to both the exposure and the variable, but is not an intermediate factor on the causal pathway between the 2
- leads to under or over estimation of a causation between E and D
- e.g. age

Question 11

matching

Answer 11

Collect information on potential confounders and adjust for them

Question 12

p-value

Answer 12

the probability that the result could have arisen by chance if there is no genuine association or effect (the null hypothesis)

Question 13

odds ratio

Answer 13

a ratio of the odds between 2 groups
- most commonly in case control studies
- it is defined as
odds of exposure in cases/odds of exposure in controls

• if the disease is rare (incidence below 10% each year) we can say the odds ratio is a good estimate of relative risk

Question 14

list some sources of bias (might not come up)

Answer 14

• Selection bias = control group incomparable (older)
• Info bias = how we collect data from cases and from controls (case dies then we need to approach a friend)
• Recall bias = recalling past info differs between case and control
• Interviewer bias = may influence how info is collected - push cases more than the controls (blind them or train them better)

Question 15

relative risk

Answer 15

risk or rate of health outcome in exposed/unexposed

• used as a measure of the strength of the association between a risk factor and a health outcome of interest
• 1 implies no effect of exposure on disease occurence (>1 implies hazard <1 implies protective effect)

Question 16

absolute risk difference

Answer 16

risk or rate in the exposed group - risk or rate in the unexposed group

(if risk is assumed to be causal it can be called attributable risk)

Question 17

point/period prevalence

Answer 17

number of cases of a disorder present of a point in time (specified time interval) per recruited study population

Question 18

incidence

Answer 18

number of new cases of a disorder that develop in specified time interval per recruited study population

Question 19

systematic reviews

Answer 19

A systematic review of the literature represents a ‘ systematic assembly, critical evaluation and synthesis of all relevant studies on specific topic’

Question 20

disease prevention

Answer 20

hindering or stopping a disease process from occurring

Question 21

primary prevention

Answer 21

Disease status: not present
Detail:
- remove causal exposure
- enhancement of host resistance
- interfere with disease pathogenesis

Question 22

secondary prevention

Answer 22

Disease status - early disease present
Detail:
* Encourage early identification of disease
* Encourage early treatment
* Ensures treatment is given at EARLY stage of disease to cure or delay progression

Question 23

tertiary prevention

Answer 23

Disease status - established or late disease present
Detail
* Ensures effective treatment in order to prevent complication and limit disability and distress

Question 24

population attributable risk

Answer 24

measures overall amount of disease risk in population associated with a particular cause

attributable risk x proportion of population exposed to risk

(e.g. how much risk of CHD does high BP cause in the population as a whole)

Question 25

population attributable risk fraction

Answer 25

proportion of all disease in population associated with that cause

risk due to exposure of interest/all risk in the population

(e.g. what proportion of all risk of CHD is explained by high BP?)

Question 26

high risk strategy

Answer 26

identification and clinical management of individuals with high risk factors

Question 27

population strategy

Answer 27

no identification, reduces everyone’s risk profile but a population wide change (change in diet e.g.)

Question 28

detection rate AKA sensitivity

Answer 28

proportion of subjects with the disease who test positive on screening test

Question 29

false positive rate

Answer 29

proportion of unaffected individuals with a positive screening result

Question 30

specificity

Answer 30

proportion of subjects without the disease who test negative on screening test

Question 31

positive predictive value

Answer 31

proportion of subjects with positive test results who actually have the disease
- a consequence of test results

Question 32

odds of being affected given a positive result

Answer 32

ratio of the number of subjects with the disease : those without the disease among those that tested positvely

• a consequence of test results

Question 33

negative predictive value

Answer 33

proportion of subjects with negative test results who do not have the disease

Question 34

list the bradford hill criteria (might not come up)

Answer 34

BACCPESTS
- biological gradient
- analogy/independence
- consistency
- coherence
- plausability
- experiment
- strength of association
- temporality
- specificity

Question 35

standardised mortality ratio

Answer 35

observed deaths:expected deaths
(if that population had same death rates as the standard population)

Question 36

confidence interval

Answer 36

we are 95% confident that the interval contains the true population value
it indicates a statistically significant difference between the groups if it does not include
- 1 in a ratio
- 0 in a subtracted difference

e.g. risk of getting diabetes 0.86 (CI - 0.78-0.95)
- also say that the true reduction in risk (reduction/increase etc) may be as great as 22% or as small as 5%

Question 37

number needed to treat

Answer 37

number of patients that need to be treated in order for ONE person to have a positive outcome