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LMAP 1b > Epidemiology > Flashcards

Epidemiology Flashcards

1
Q

What is epidemiology?

A

How often diseases occur in different groups and why

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2
Q

What is primary prevention?

A

Control of exposure to risk factors

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3
Q

What is secondary prevention?

A

Detection of early departures from health and treatments to slow progression of disease

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4
Q

What is exposure?

A

the variable that we are trying to associate with a change in health status

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5
Q

What is outcome?

A

Result of the exposure

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6
Q

Name three examples of exposures in epidemiology

A

Drugs, behaviours, demographic characteristics

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7
Q

What is epidemiological transition?

A

changing patterns of population distributions in relation to changing patterns of mortality, fertility, life expectancy, and leading causes of death

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8
Q

Which diseases are more prevalent in resource constrained societies?

A

Infectious diseases

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9
Q

How can infectious diseases be overcome?

A

improved access to water, sanitation, hygiene, vaccines and antibiotics

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10
Q

Which diseases are more prevalent in well-resourced societies?

A

Non-communicable diseases

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11
Q

What are the three groups of diseases?

A

Communicable
Non-communicable
Injuries

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12
Q

What are disability adjusted life years/DALYs?

A

measure of disease burden that combines years of life lost from ill-health, disability or premature death

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13
Q

What are the four measures of frequency?

A

Odds
Prevalance
Cumulative Incidence
Incidence Rate

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14
Q

What is the correct epidemiological definition of odds?

A

The ratio of the probability (P) of an event to the probability of its complement (1-P)

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15
Q

What is the epidemiological definition of prevalence?

A

The proportion of individuals in a population who have the attribute at a specific timepoint

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16
Q

What is the epidemiological definition of cumulative incidence?

A

The proportion of the population with a new event during a given time period.

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17
Q

What is the epidemiological definition of incidence rate?

A

The count of new cases during the follow-up period, divided by the total person-time

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18
Q

What is person time?

A

an estimate of the actual time-at-risk that all participants contributed to a study (can be in months, days, years, etc)

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19
Q

Which measures of frequency are time dependent?

A

Cumulative incidence and incidence rate

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20
Q

What is an advantage of incidence rate over cumulative incidence

A

Participants can join or leave the study at any time

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21
Q

What is a disadvantage of cumulative incidence?

A

All patients must enter study and have follow up at the same time.

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22
Q

What is standardisation in epidemiology?

A

A way to summarise disease rates or mortality in different populations, taking account of variations in age structure, sex or other potential confounders, so that comparisons between populations remain meaningful.

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23
Q

What is direct standardisation?

A

A type of adjustment which allows us to compare like-for-like between populations. Provides a comparable incidence

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24
Q

What do you need for direct standardisation?

A

Age/sex-specific incidence and a standard population

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25
Q

Can the crude incidence be higher/lower than the direct standardised incidence?

A

Yes

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26
Q

Does a higher incidence of disease in one area compared to another also mean that there are more people with the disease in that area?

A

No, depends on population size

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27
Q

What is indirect standardisation?

A

Where the number of events or the mortality rates in each age group is unknown. Provides a ratio out of 100/1

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28
Q

When is indirect standardisation used?

A

When we don’t know age/sex-specific data

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29
Q

What is unwarranted variation?

A

Higher mortality due to dangerous practise

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30
Q

What is explained variation?

A

Higher mortality that is not due to malpractice e.g. higher risk blend of procedures

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31
Q

What is statistical artefact

A

Higher mortality due to better recording of mortality rather than more deaths occurring

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32
Q

Why is the blend of procedures easier to find out than who is getting the procedures

A

Billing for procedures

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33
Q

What do we need for indirect standardisation for hospital mortality

A

Procedure bills and national mortality statistics for each procedure

34
Q

What is the standardised mortality ratio/SMR?

A

The ratio of observed deaths to expected deaths (O:E)

35
Q

What is the standardised incidence ration/SIR

A

The ratio of observed cases of a disease in a population to expected cases (O:E)

36
Q

What is the Summary Hospital-level Mortality Indicator/SHMI?

A

Indicator which uses the process of indirect standardisation to produce ‘expected’ number of deaths. Identifies hospitals with higher than expected mortality.

37
Q

What are the two types of literature review?

A
  • narrative review
  • systematic review
38
Q

What is a narrative review?

A

Brings together the published literature into a single article enabling the reader to quicklly understand the issue

39
Q

What is a systematic review?

A

Sets out a highlt structred approach to searching, including and summarising literature, often presented as the basis for meta-analysis

40
Q

What are the strengths of narrative reviews?

A
  • easier and faster to write so may be more up to date
  • useful for looking at areas with limited research
  • useful for when work from different disciplines is being brought together with a research question that is difficult to answer
41
Q

What are the limitations of narrative reviews?

A
  • subject to bias since authors are free to pick and choose which research is included
  • some evidence may be omitted by chance
42
Q

What are the strengths of systematic reviews?

A
  • collate all available evidence that relates to a highly focused research question
  • structured search enables reproducability
  • inclusion criteria for evidence
  • can take many months to design
43
Q

What is the process of a systematic review?

A
  1. research question
  2. structured search
  3. indices
  4. screening/inclusion
  5. reporting
  6. writing
  7. submitting, revising and publishing
44
Q

How long can systematic reviews take to publish?

A

18-24 months

45
Q

What is a structured search?

A

A technology for querying multiple data sources in an independent and scalable manner. It occupies the middle ground between keyword search and database search.

46
Q

What are indices in research?

A
  • Lists of all the names, subjects and ideas in a piece of written work, designed to help readers quickly find where they are discussed in the text
  • e.g. medline, mbase, psychinfo, etc
  • must be made clear which search indices where used and the time period
47
Q

What is the difference between an index and registry?

A
  • index = based on published research
  • registry = registration of research which is incomplete or unpublished
48
Q

Why are registries important?

A

To prevent duplication, omission and bias in research

49
Q

What is the PRISMA diagram?

A
  • a flow diagram which visually summarises the screening process
  • the four stages are identification, screening, eligibility and included
  • shows the n at each stage
50
Q

How many pieces of evidence will be found at the beginning and end of the screening process?

A
  • start with 1000-3000
  • end with 10-30
51
Q

What are the limitations of systematic reviews?

A
  • only as good as the method used, indices searched and evidence incorporated
  • become outdated very quickly - need to look at the search date not the publication date
52
Q

What is grey information/literature?

A
  • literature that has not be reviewed and published through academic journals
  • hasn’t been peer reviewed and won’t be found on online indices like pubmed
  • can be found on Google Scholar and OpenGrey
  • e.g. government reports
53
Q

Can grey literature be incorporated into research?

A

Yes but with caution

54
Q

How are narrative and systematic reviews useful?

A
  • as a starting point
  • can look into the individual literature that makes up the reviews
  • can look into more recent citations of the reviews using online indices
55
Q

What is the Cochrane Collaboration?

A
  • the world’s largest organisation dedicated to the preparation and maintenance of systematic reviews
  • aims to help people make well-informed health decisions
56
Q

What is a meta-analysis?

A

a statistical process that combines the data of multiple studies to find common results and to identify overall trends

57
Q

How is a meta-analysis different to a systematic review?

A
  • systematic review = combining study data in a number of ways to reach an overall understanding of the evidence
  • meta-analysis = combining the quantitative findings of several separate studies into one pooled estimate
58
Q

How are the pooled estimates of a meta-analysis presented?

A

Forest plot

59
Q

What are the components of a forest plot?

A
  1. Studies
  2. Intervention group
  3. Control group
  4. Relative risk (shown numerically and on forest plot)
  5. Weight
60
Q

What do the intervention and control group together show?

A

The number of participants in the study

61
Q

What does the vetical line at one in a forest plot indicate?

A

the line of no effect

62
Q

What are the size of the squares in a forest plot proprtional to?

A

The number of participants in the study

63
Q

What do the whiskers around the squares in a forest plot show?

A

the level of confidence

64
Q

What does the position of the squares in a forest plot indicate?

A
  • left of line of no effect = negative effect/attenuation
  • right of line of no effect = positive effect
65
Q

Which side of the line of no effect will the null hypothesis be on in a forest plot?

A

can be either side depending on what is being investigated

66
Q

What does the diamond in a forest plot represent?

A

The pooled estimate

67
Q

What do the left and right points of the diamond represent in a forest plot?

A

levels of confidence

68
Q

What does it mean when the lateral point of a diamond crosses the line of no effect in a forest plot?

A

level of confidence is low, cannot reject the null hyposthesis

69
Q

What is heterogeneity in meta-analysis?

A

The differences between the studies being pooled

70
Q

What are the three types of heterogeneity we are concerned with?

A
  • clinical (patients, selection criteria)
  • methodological (study design, blinding, intervention approach
  • statistical (differences in reporting)
71
Q

What are the two ways of weighting in a meta-analysis?

A
  • fixed effects
  • random effects
72
Q

What is a publication funnel plot?

A

assesses the likelihood of publication bias arising

73
Q

What is a trial endpoint?

A

an outcome that usually describes a clinically meaningful outcome
e.g. survival in cancer trials

74
Q

Should the endpoint be a priori or a posteriori?

A

a priori

75
Q

What are the measures for clincial trial outcomes?

A
  • Saftey (a)
  • Efficacy (how well a therapy works in achieving a desired outcome)
76
Q

What are the two types of efficacy endpoint?

A

primary and secondary

77
Q

What is a primary efficacy endpoint?

A

the endpoint for which the study has been made

78
Q

What is the secondary efficacy endpoint?

A
  • a second, ‘softer’ measure that is studied alongside the primary endpoint
  • can still be usefful even if the primary endpoint isn’t proven
79
Q

What is the composite endpoint?

A
  • multiple potential endpoints added together
  • common when the outcomes measured are uncommon
80
Q

What is survival analysis?

A

d

81
Q

What is used to portray survival analysis?

A

Kaplan-Meier plots

LMAP 1b (1 decks)

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