Measures of Impact Flashcards

1
Q

What are 2 ways to describe the frequency of disease in a population?

A
  • incidence: rate, risk, CI

- prevalence: proportion

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2
Q

Frequency numerically describes ______

A

The movement of well to ill/force of disease (incidence)

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3
Q

Prevalence

A

The commonness of disease at a time point/window

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4
Q

________ describes those factors/exposures related to disease

A

Measures of association

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5
Q

Cohort study - summary

A

Monitor a cohort exposed to a factor, and another unexposed

  • risk of disease in each cohort is calculated
  • RR: numerical multiplier of risk in exposed, compared to unexposed
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6
Q

Case-control study - summary

A

One group of cases, the other non-cases

  • odds of exposure to punitiive risk factors is calculated for cases and non-cases
  • OR: numerical multiplier of odds that expressed association between cases and exposure
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7
Q

_____ is an estimate of RR

A

OR

- interpreted the same, represent the same exposure, disease relationships

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8
Q

Measures of impact

A

Describe the impact of exposures/disease at the population level

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9
Q

RR is reflective of the _____

A

Whole population

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10
Q

If you contain exposure, then you will _______

A

Reduce the amount of disease

- there will still be some incidence of disease without exposure

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11
Q

What happens if you decrease the % exposure?

A

Many fewer exposed

  • much less D+
  • changed number of cases and distribution of cases
  • occurs even if relative risk remains the same!!
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12
Q

If you have a high number of unexposed, then decreasing the %exposed would ______

A

Not reduce the incidence of disease!

- there may be another exposure that is causing disease

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13
Q

How is RR misleading at the population level?

A
  • most disease is not related to exposure
  • there is “baseline” disease occurence in E-, and disease is not reliant on a single type of exposure (multifactorial disease)
  • still, those who are exposed carry a much higher risk of disease
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14
Q

Why do we still use RR?

A

The relative exposure: disease relationship tends to hold at this level, regardless of baseline risk variation
- no matter what the disease incidence in the E- group is, the RR does not change!!

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15
Q

What are 4 measures that compliment the RR and describe disease at the population level?

A
  • attributable risk (exposed, aka risk difference)
  • population attributable risk
  • attributable fraction (exposed)
  • population attributable fraction
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16
Q

Attributable risk

A

Difference in risk (incidence) between exposed and unexposed groups

  • ____ cases per 100 animals
  • a/(a+b) - c/(c+d)
  • expresses increased incidence of disease, over the baseline, in exposed animals
17
Q

AR directly applies to _____

A

Exposed animals only

  • for every 100 animals exposed, expect an additional ____ cases
  • over baseline
18
Q

Population attributable risk

A

Difference in risk (incidence) between the total population and unexposed group

  • (D+/N) / (D+/E-) minus D+/E-
  • ___ cases per 100 animals in the population
  • expresses amount of disease in the total population attributable to exposure —> if exposure were eliminated, ___% of population would not be affected with D+
19
Q

PAR applies directly to _____

A

Population

  • in ______ animals, ___ cases could be eliminated if you eliminate exposure
  • if you eliminate exposure, everybody is at the same risk of disease as the E-
20
Q

Attributable proportion

A

Proportion of incidence in exposed that is attributed to the exposure

  • what fraction (%) of disease in the exposed is really due to exposure?
  • (RR-1)/RR
  • among exposed, ___% of D+ is due to exposure
21
Q

Disease in E+ =

A

Baseline + disease associated with exposure

22
Q

Population attributable proportion

A

Proportion of incidence in population attributed to exposure

  • what fraction (%) of disease in the population is due to exposure?
  • the disease incidence that would be eliminated if the E+ group had incidence equal to the E- group
  • (incidence in population - incidence in E-)/incidence in population
  • ____% of disease in the population can be eliminated if you eliminate E+
23
Q

AR - summary

A

Expresses the increased incidence of disease, over the baseline, in exposed animals
- exposed

24
Q

PAR - summary

A

Expresses the amount of disease in the total population attributable to exposure
- total population

25
Q

AP - summary

A

Proportion of disease in exposed attributed to exposure

- exposed

26
Q

PAF - summary

A

Fraction (10%) of disease in the population due to exposure

- population