Epidemiology: Key concepts Flashcards

1
Q

Meaningful mortality rate statistics need what?

A

A denominator population (how many people) and a time frame

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2
Q

What is a denominator and name some examples?

A
  • It is where the deaths have happened. Examples include:
  • Health board,
  • City,
  • Hospital,
  • Disease register,
  • Recruited to a study
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3
Q

Name some examples of observational studys

A

Case series, cross sectional study, cohort study and case controlled study.

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4
Q

What is a case series?

A

A series pf cases with the same disease

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5
Q

What is a population case-series (ecological studies)

A

Unit of study is a whole population, and these are useful to study signs and symptoms and look for causal hypotheses.

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6
Q

What is standardisation?

A

A set of techniques based on weighted averaging used to remove the effects of differences in age or other confounding variables when comparing two populations.

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7
Q

What are some of the limitations of ‘crude’ rates?

A

They are of limited value when comparing two populations with different structures because of confounding variables.

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8
Q

What are the methods of direct and indirect standardisation?

A

Direct - Using known age-specific mortality rates to standardise.
Indirect - Using a reference population when the age-specific mortality rates are unknown to standardise

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9
Q

What is the SMR?

A

The standard mortality rate. Compares the number of deaths to the number of expected deaths.

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10
Q

What is a confounding variable?

A

A third variable that also has an effect on your dependent variable.

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11
Q

What are two methods of dealing with a confounding?

A

Study design and data analysis (standardisation)

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12
Q

What is mean’t by confounding?

A

Confounding is the distortion of the association between an exposure and health outcome by an extraneous, third variable called a confounder.

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13
Q

What is bias?

A

An error in the conception and design of a study leading to results or conclusions that are systematically different from the truth.

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14
Q

Describe how systematic errors can occur

A

In what data is collected, how the data is collected, analysed, interpreted or reported.

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15
Q

Bias can lead to wrong conclusions about?

A

Disease causation and treatment effectiveness

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16
Q

What is at the bottom and the top of the evidence hierarchy?

A

Bottoms - editorials and expert opinions.

Top - Systematic review.

17
Q

What is Bradford Hill criteria for Causality?

A

Strength of association, consistency, specificity, temporality, biological gradient, plausibility, coherence, experiment and anaolgy.

18
Q

Why is consistancy a criteria?

A

A causal link is more likely if the association is observed in different studies and different sub-groups (reporducibility)

19
Q

Why is specificity a criteria?

A

Causal link is more likely when a disease is associated with ONE specific factor

20
Q

Why is biological gradient a criteria?

A

A causal link is more likely if different levels of exposure to the factor leads to different risks of acquiring the outcome.

21
Q

Why is plausibility a criteria?

A

A causal ink is more likely if a biologically plausible mechanism is likely or demonstrated

22
Q

Why is coherance a criteria?

A

A causal link is more likely if the observed association conforms with current knowledge.

23
Q

Why is experiment a criteria?

A

A causal link is very likely if removal or prevention of factor leads to reduced or non-existent risk of outcome.

24
Q

Why is analogy a criteria?

A

A causal link is more likely is analogy exits with other diseases, species or settings.

25
Q

Why is temporality a criteria?

A

Causal link is more likely if exposure to assumed causes has been shown to come before the outcome