Definitions and Equations Flashcards

1
Q

Exposure AKA risk factor/determinant

A

any factor that may influence the outcome

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2
Q

outcome

A

the disease, or event or health related state under study

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3
Q

prevalence

A

number of existing cases in a population at a designated time (per 1000)

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4
Q

point prevalence

A

the proportion of persons in a defined population that has the outcome under study at a specific point in time

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5
Q

period prevalence

A

the proportion of persons in a defined population that has the outcome under study over a period of time

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6
Q

incidence

A

number of new cases (per 1000) in a defined period

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7
Q

incidence risk

A

number of new cases in interval/ population initially at risk e.g. mortality rare (static populations)

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8
Q

annual incidence

A

count deaths over calendar year, use mid-year population as denominator, assume population size constant over the year. Expressed as cases per 100,000 per year

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9
Q

incidence rate of rare diseases expressed as

A

per 1,000,000

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10
Q

incidence rate of common diseases expressed as

A

per 1,000

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11
Q

cumulative incidence eqn

A

frequency of new cases over a specified period/ number of people at the start of the period

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12
Q

what assumptions does cumulative incidence make

A

everybody is followed for same length of time
no major changes in death rates

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13
Q

what is the benefit of person years incidence over culualtive incidence

A

it allows for loss to follow up

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14
Q

prevalence eqn

A
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15
Q

dependency ratio

A

the proportion of economically inactive people (due to age)

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16
Q

dependency ratio

17
Q

infant mortality rate

A

(number of deaths of infants aged 0-1 year/number of live births)
for a specific time-period. Reported as infant deaths per 1000

18
Q

under 5 mortality rates

A

(no. of deaths of infants 0-5 years/no of live births) for a specific time-period. Reported as infant deaths per 1000

19
Q

maternal mortality ration (MMR)

A

ratio of the number of maternal deaths during a given time period per 100,000 live births during the same time-period

20
Q

fertility rate

A
  • live births per 1,000 women per year
    aged 15 – 44 years
    aged 15 – 49 years (general fertility rate)
  • age specific fertility rates
21
Q

total period fertility rate (TPFR)

A

average number of children that would be born to a woman over her lifetime, assumes that a woman has the same fertility as the population on average and lives beyond the maximum age of giving birth

22
Q

what do different TPFRs indicate

A

o TPFR > 2.1 population increasing
o TPFR < 2.1 population decreasing

23
Q

life expectancy

A
  • The number of years a baby born today can be expected to live IF it experienced the current age-specific mortality rates
  • An average for the whole population – some people will live longer other less
24
Q

life expectancy calculation

A

Apply age specific mortality rates – 0-1, 1-4, 5-9, 10-14…..50-54…..105-109 – in sequence to a population of 100,000 – add up the total number of years lived / 100,000

25
healthy life expectancy definition and 2 types
* Expected years of life in good or fairly good general health * Assumes current patterns of mortality and morbidity remain unchanged * Calculation similar to life expectancy * Two types o life expectancy in good general health o disability-free life expectancy (no long term limiting illness)
26
Potential years of life lost (PYLL)
* A measure of the relative impact of various diseases and lethal forces on society. * Highlights the loss to society from early deaths.
27
PYLL calculation
chose a maximum age and find number of years of life 'lost when a person dies prematurely calculate average number lost all causes of death or specific causes e.g. cardiovascular
28
DALY (disability adjusted life year)
DALY – = years lost (death) plus years spent with disability (allowing for the amount of disability) * 1 DALY= 1 healthy year of life lost * Measure of burden of disease – extent to which disease reduces healthy years of life
29
DALY calculation
* Calculated for specific diseases * Disability plus mortality * Disability – = incidence x duration x disability * Mortality – years lost through early death
30
epidemiology definition
The study of the distribution and determinants of health-related states or events (including disease) in a population. Includes identifying risk factors for disease to determine biological pathways and inform healthcare policy
31
descriptive epidemiology
epidemiological studies that focus on the descriptive components rather than analytical components
32
stillbirth rate
the number of stillbirths per 1000 healthy births within a unit of time
33
prevalence
P = I x D