Epidemiology 1 Flashcards by Adele Schiff

What are the three types of prevention?

Primary
Secondary
Tertiary

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What is primary prevention?

The prevention of disease through the control of exposure to risk factors

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What is an example of primary prevention?

Reducing salt in your diet reduces the. risk of developing hypertension

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What is secondary prevention?

The application of available measures to detect early departures from health and to introduce appropriate treatment and interventions

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What is an example of secondary prevention?

Controlling hypertension with antihypertensive drugs to progression

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What is tertiary prevention?

The application of measures to reduce or eliminate long-term impairments and disabilities, minimising suffering caused by existing departures from good health and to promote the patient’s adjustments to their condition

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What is an example of tertiary prevention?

Rehabilitation for someone who’s had stroke so that they can return as close as possible to their pre-morbid activities

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What are different types of exposure?

e.g. drug, behaviour (dietary sodium intake) or demographic characterise (ethnicity)

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What is the exposure and outcome?

Exposure: independent variable
Outcome: dependent variable

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What are the levels of evidence in research?

Systematic reviews and meta analysis
Randomised controlled trials
Cohort studies
Case-control studies
Case series, case reports
Editorials, expert opinion

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What does qualitative research explore?

underlying ideas and themes to inform research questions and possible future hypothesis

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What does qualitative research express?

Its findings and outputs of qualitative research in words

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What does qualitative research rely on?

Smaller numbers of participants but goes in substantial detail

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When is qualitative research used for?

used earlier in research process - gives you a place to start

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What numbers and measures are used?

Measures of frequency and associations

2. Comparisons and adjusting for differences

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Where do these measures come from?

Descriptive epidemiology
Observational and interventional study design
Systematic reviews and meta-analysis

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How do we interpret epidemiological findings?

Association, causation, validity and bias

2. Confounding and effect modification

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What is the DALY?

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

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What are some measures of frequency?

Odds
Prevalence
Cumulative incidence
Incidence rate

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How do you calculate odds?

number of people with the disease / number of people who don’t have the disease

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What is the definition of odds?

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

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What is prevalence?

the proportion of individuals in a population who have the disease or attribute of interest at a specific timepoint

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How do you calculate prevalence?

number of people with the disease / total number of individuals in the population

What does prevalence not show?

no information on new cases of a disease

When is prevalence unhelpful?

- in short duration disease | - for causal inference

What is cumulative incidence?

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

How do you calculate cumulative incidence?

number of new cases during the period of interest / number of disease free individuals at the start of this time period

Are there units for cumulative incidence?

No units - 0-1

What does a cumulative incidence of 0 mean?

(0%) means there were no new cases during the study period

What does a cumulative incidence of 1 mean?

(100%) means that all individuals developed the disease during the time period

What do you have to be explicit with in cumulative incidence?

Timing

When is cumulative incidence not well defined?

- Need follow up period must be the same participants - but not always possible lost participants, or someone get killed by car accident in follow up period despite about cancer diagnosis as no longer at risk of cancer diagnosis

What is person time?

measure the time participants spend in the study (at risk of developing disease) (sum up time observed for every person during study period) - until develop disease/die or lost to follow up

What is incidence rate?

the number of new case per unit of person time

How do you calculate incidence rate?

number of new cases during follow up period / total person-time by disease free individuals

What values can incidence rate take?

Take values of 0 to infinity

What are the units of incidence rate?

person time

What does incidence rate account for?

- time of follow ups and time for new event occurred | - Deal with lost follow up or enter and leave the study at different times and competing risks

When is incidence rate used?

When cumulative incidence cannot be properly defined

What does standardisation allow?

Want to understand whether the difference in incidence might be down to their different demography: sex and age

What does direct standardisation give?

gives comparable incidence - e.g. 120 strokes per 100K/year

What does indirect standardisation give?

Gives ratio out of 100 (sometimes 1.0)

When should you used indirect standardisation?

- When don't know age specific data | - Only have high-level data about outcomes but can't make direct comparison

How do you calculate the standardised mortality ratio (SMR)?

diving observed count by expected count

What would SMR of 1.65 mean?

65% more deaths than expected

What is SHMI data used?

For hospital performance identifying hospitals that report higher than expected mortality

What does standardisation not account for?

Change and confined intervals

How does the SHMI work?

1. uses the process of indirect standardisation to produce ‘expected’ number of deaths by a series of adjustments taking into account the volume of cases, blend of diagnoses and casemix adjustments for underling demography and health status variation of patients 2. A range of adjustments for casemix are undertaken and used to calculate an SHMI value (ranging from 0.6 to 1.2)

What is prevalence and incidence?

1. Prevalence: all cases / total population | 2. Incidence: new cases / population that can get disease

What does prevalence take into account?

incidence, recovery rate and death rate (no longer cases)

Why do you use person time?

- Incidence rate cannot be done at a specific moment | - Hard to follow up over study period

What happens in calculating cumulative incidence in Individuals who already had disease when period of interest started?

not be included in denominator or numerator

What are two different names for cumulative incidence?

- Incidence proportion | - Risk

What do you need for cumulative incidence?

Follow up

When can rates be used?

Can only be expressed as new cases per unit of person time

What does prevalence account for?

reflects both duration and occurrence

What can odds and prevalence be used for?

1. Assess health of population 2. To plan health services and allocate healthcare resources 3. To monitor trends of diseases over time