PHEBP Definitions Flashcards
epidemiology
the study of the distribution and determinants of health-related states or events in populations (and the application of this to control population health)
public health
the art and science of preventing disease, prolonging life and promoting health through the organised efforts of society
exposure
lack of vitamin D, poor diet (any factor associated with an outcome of interest)
outcome
health outcome like getting diabetes
risk
intuitive understanding that it is something that increases our likelihood of harm
ecological study
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
cross sectional study
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
cohort studies
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
case-control studies
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
confounding
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
matching
Collect information on potential confounders and adjust for them
p-value
the probability that the result could have arisen by chance if there is no genuine association or effect (the null hypothesis)
odds ratio
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
list some sources of bias (might not come up)
- 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)
relative risk
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)
absolute risk difference
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)
point/period prevalence
number of cases of a disorder present of a point in time (specified time interval) per recruited study population
incidence
number of new cases of a disorder that develop in specified time interval per recruited study population
systematic reviews
A systematic review of the literature represents a ‘ systematic assembly, critical evaluation and synthesis of all relevant studies on specific topic’
disease prevention
hindering or stopping a disease process from occurring
primary prevention
Disease status: not present
Detail:
- remove causal exposure
- enhancement of host resistance
- interfere with disease pathogenesis
secondary prevention
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
tertiary prevention
Disease status - established or late disease present
Detail
* Ensures effective treatment in order to prevent complication and limit disability and distress
population attributable risk
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)
population attributable risk fraction
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?)
high risk strategy
identification and clinical management of individuals with high risk factors
population strategy
no identification, reduces everyone’s risk profile but a population wide change (change in diet e.g.)
detection rate AKA sensitivity
proportion of subjects with the disease who test positive on screening test
false positive rate
proportion of unaffected individuals with a positive screening result
specificity
proportion of subjects without the disease who test negative on screening test
positive predictive value
proportion of subjects with positive test results who actually have the disease
- a consequence of test results
odds of being affected given a positive result
ratio of the number of subjects with the disease : those without the disease among those that tested positvely
- a consequence of test results
negative predictive value
proportion of subjects with negative test results who do not have the disease
list the bradford hill criteria (might not come up)
BACCPESTS
- biological gradient
- analogy/independence
- consistency
- coherence
- plausability
- experiment
- strength of association
- temporality
- specificity
standardised mortality ratio
observed deaths:expected deaths
(if that population had same death rates as the standard population)
confidence interval
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%
number needed to treat
number of patients that need to be treated in order for ONE person to have a positive outcome
