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PoplHlth 111 > Test 1 > Flashcards

Test 1 Flashcards

1
Q

Define epidemiology

A

The study of how much dis-ease occurs in groups or populations, and the factors that determine differences in dis-ease occurrence between different groups.

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2
Q

What is a dis-ease occurrence and what are the two subtypes?

A

The transition from a non-dis-eased state to a dis-eased state. If it is easily observable (eg car accidents) it is an ‘event’. If it is not, it will be counted as number of people in a ‘state’.

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3
Q

What is a population?

A

Any group of people who share a specified common factor

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4
Q

Why is epidemiology useful?

A

Gives information about types of services required, what causes or predictors might be, whether treatments work and can give advice on health planning, prevention and treatment strategies.

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5
Q

What is important when counting the number of dis-ease outcomes?

A

All must come from the population

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6
Q

What is the overreaching epidemiological equation?

A

N/D (Number of persons with dis-ease/Number of persons in population) (Numerator over denominator)

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7
Q

What must always be asked in any study?

A

What is the denominator?

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8
Q

What is EG?

A

Exposure group

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9
Q

What is CG?

A

Control group

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10
Q

What is EGO?

A

Exposure group outcomes

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11
Q

What is CGO

A

Control group outcomes

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12
Q

What is incidence?

A

The proportion of people from the study population in whom a dis-ease occurs during a specified time period

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13
Q

What can be measured using incidence?

A

Deaths, events which only happen/tend to happen once which can be easily observed.

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14
Q

How is incidence calculated?

A

Measuring the number of onsets of dis-ease occurring during a period of time.

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15
Q

What is the formula for calculating incidence?

A

General: N/D/T
EG: outcomes in EG/no in EG / Time
CG: outcomes in CG/no in CG / Time

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16
Q

What is prevalence?

A

A static measure of how much dis-ease there is at a point in time.

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17
Q

Why is prevalence not entirely accurate?

A

It misses things like people who have recently died or been cured. Therefore the prevalence is actually greater than the results would suggest.

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18
Q

How is prevalence measured?

A

Counting the number of people with dis-ease at one point in time, and then dividing by the number of people in the study group at that point in time

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19
Q

When is prevalence used?

A

When it is not easy or practical to count events. Eg. transition to obesity does not have a set turning point, so simply count those obese. Asthma attacks happen multiple times to each person, so can’t count the number of attacks- falsely high prevalence. Often two points in time are compared.

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20
Q

What is period prevalence?

A

Defining the presence of dis-ease based on the number of onsets that have occurred over a period of time, and converting this into a single measure of dis-ease at a point in time.

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21
Q

What is a risk ratio?

A

Also called relative risk. It is EGO/CGO.

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22
Q

What is risk difference?

A

Also called absolute risk. It is EGO - CGO

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23
Q

What is RRR?

A

Relative Risk Reduction- when the relative risk for EGO is less than 1 compared to CGO, this is said to have been ‘reduced’. Therefore it can be claimed that the treatment reduces the risk

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24
Q

What is RRI?

A

Relative Risk Increase- when the comparative risk is above 1, we can see that the treatment increases risk

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25
Q

What does RAMBOMAN stand for?

A

Recruitment, Allocation, Maintenance, Blind and Objective Measurements, ANalysis

26
Q

What is involved with recruitment?

A

Is the setting well described and are the study goals appropriate?
Are participants representative of the population?
Is there selection bias? (eg Ex group recruited from a different group than Co group- smokers vs non smokers).

27
Q

What are the downfalls of recruitment error?

A

It can cause confounding, and give a result which doesn’t represent the whole population

28
Q

What is involved with allocation?

A

The method used to allocate subjects- randomly or by measurement. Also the groups to which subjects are allocated.

29
Q

What are the downfalls of allocation?

A

If people are allocated by measurement, they often have differences besides those being studied. This causes confounding. In addition, patients may lie or give moderated answers due to being embarrassed. This can cause them to be allocated to the wrong group.

30
Q

How can allocation be at its best?

A

Participants should be randomly allocated to groups, and measurement should be blind and objective to ensure they are allocated to the right groups.

31
Q

What is involved with Maintenance?

A

Whether participants remain in the groups they were originally placed in or if they don’t. Also whether they drop out of the study, or move away or become unreachable.

32
Q

What are the consequences of maintenance error?

A

The results may not be valid as the treatment may not be the reason for any change. It also means the full extent of the treatment may not have been experienced, and that the population’s numbers drop.

33
Q

What study has not maintenance error?

A

Cross sectional studies

34
Q

How can maintenance errors be minimized?

A

Shorter follow up periods, easier to stick to treatments (eg. no diets)

35
Q

What is Blind Objective measurement?

A

Blind measurement is when either the participants or the experimenters are unaware of who is receiving treatment vs placebo. Objective measurement refers to whether the results are based on a definite view (eg blood cholesterol) or a subjective view (eg. how much pain are you in).

36
Q

How can BOM create issues?

A

If participants and experimenters are not blind, they may feel differently or be treated differently, This can result in different results based on psychological effects. How things are measured affects whether participants are allocated into the right groups or not.

37
Q

What is a confidence interval?

A

The (probability) chance that the true value for the population lies between these values.

38
Q

What is the difference between random and non-random/systematic error?

A

Random error is inherent in every study as you can never know the true population value. It cannot be eradicated, but reduced by larger population sizes. Systematic error is committed by the experimenters and participants, and can be eradicated.

39
Q

When is a study’s results deemed statistically significant?

A

When the CI (diff) does not touch or cross 0.

40
Q

When is a study clinically significant?

A

When the benefit of a treatment is large enough that it will make a real difference to patients’ lives- eg. if only 1 person per 10,000 will be benefited, it is less significant than if 100 per 10,000 are benefited.

41
Q

What is meta-analysis?

A

When multiple confidence values for different studies are combined to give a more overall view of the effects of a treatment. This gives results closer to the actual population value.

42
Q

What is the purpose of an RCT?

A

Investigate effects of different interventions on dis-ease occurrence in different groups of individuals

43
Q

What is the main application of an RCT?

A

Drug studies

44
Q

What are the main features of an RCT?

A

Longitudinal and experimental. Random allocation. Follow up period for dis-ease occurrence measurement

45
Q

What are the advantages of an RCT?

A

Minimizes confounding

46
Q

What are the disadvantages of an RCT?

A

Ethical issues, difficult, maintenance issues, costly- means studies usually small so lots of random error

47
Q

What is the purpose of a cohort study?

A

Investigate associations between risk factors and dis-ease incidence in different gorups

48
Q

What is the main application of a cohort study?

A

Cause of dis-ease incidence or effects of intervention

49
Q

What are the design features of a cohort study?

A

Longitudinal, observational, allocation by measurement and follow up

50
Q

What are the advantages of a cohort study?

A

Cheaper than RCTs, recall bias (what was my group?) minimized as allocation occurs at start, clear sequence between exposure and dis-ease.

51
Q

What are the disadvantages of a cohort study?

A

Confounding and maintenance error

52
Q

What is the purpose of a X sectional study?

A

Measure dis-ease prevalence in groups. Investigate associations between factors and dis-ease

53
Q

What is the application of X sectional studies?

A

Prevalence of dis-ease in groups

54
Q

What are the features of X sectional studies?

A

Observational, allocation by measurement, outcomes measured at same time as allocation

55
Q

What are the advantages of X sectional studies?

A

Cheap and quick. No maintenance error

56
Q

What are the disadvantages of X sectional studies?

A

Uncertain time sequence (reverse causality), confounding, limits cause/effect comparison

57
Q

What is the purpose of an ecological study?

A

Investigate associations between exposures and dis-ease in different groups of populations

58
Q

What is the application of ecological studies?

A

Cause of dis-ease incidence and prevalence

59
Q

What are the design features of ecological studies?

A

Longitudinal or X sectional, experimental or observational. EG and CG allocated in groups rather than individually

60
Q

What are the advantages of ecological studies?

A

Cheap and quick. Useful when majority of populations are exposed or not exposed. Efficient for rare outcomes.

61
Q

What are the disadvantages of ecological studies?

A

Confounding very common

PoplHlth 111 (3 decks)

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