Risk factor for a disease/outcome e.g. obesity, socioeconomic status, gender - can increase or decrease risk of disease/outcome - those which decrease risk of disease/ (negative) outcome are protective

Research Methods - Encountering evidence Flashcards by Chrissy Taaffe

What is evidence-based medicine? (EBM)

• “the conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients” (David Sackett)
• Clinical decisions should be based on best evidence
• The problem determines the nature/source of evidence needed
• Best evidence is integrative
• Evidence should be identified, integrated,
appraised and applied
• Performance should be continually evaluated

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Clinical decisions should be based on … …

Best evidence - the problem determines the nature/source of evidence needed
Best evidence is integrative
Evidence should be identified, integrated, appraised and applied
Performance should be continually evaluated

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What is research ethical approval?

Research ethics govern the standards of conduct for researchers
Research ethics protect the dignity, rights and welfare of human and animal research participants
Research ethics approval is provided by a committee (who review a research protocol, and to ensure appropriate ethical standards are being upheld)

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Which studies require research ethical approvals?

Studies involving human/animal participants if - gathering novel data or information, creating knowledge that can be generalised beyond the participant sample or setting

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Which studies require research ethical approvals?

Studies involving human/animal participants if:

gathering novel data or information
creating knowledge that can be generalised beyond the participant sample or setting

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Which projects do not require ethical approvals?

Health improvement studies:
- service evaluations/service improvement/quality improvement (finds out something that service which can be/is used to improve that service)
- clinical audit (as per service evaluation, but evaluating service against a benchmark (e.g. national standard)
NB - NHS audits should be registered with the NHS trust in which they are being conducted

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Which committee needs to be involved if the participants are NHS patients and/or staff / work conducted on NHS site/s?

NHS health research authority

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Which committee needs to be involved if the participants are individuals (or animals/cells) recruited anywhere except the NHS site / no NHS site involved?

School research ethics officer (SREO) / BSMS RGEC (Research governance and ethics committee)

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IRP project types that require ethics approval?

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Epidemiological studies can be either …. Or ….

Descriptive: amount and distribution in populations (person, place and time)
Analytic: test hypothesis, identify and quantify risk or exposure

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Descriptive study types include (4)…

Case reports, case series, ecological studies, cross sectional or prevalence survey

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Observational study type examples (4)

Case control, cohort and ecological studies, cross sectional or prevalence surveys

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Experimental study type examples:

Clinical trials, preventive trials, community intervention trials

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Exposure is …

Risk factor for a disease/outcome e.g. obesity, socioeconomic status, gender

can increase or decrease risk of disease/outcome
those which decrease risk of disease/ (negative) outcome are protective

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Outcome is …

Disease, condition or event of interest e.g. HIV/AIDS, depression, mortality relating to cardiovascular disease

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… measures the frequency of “cases” of a disease (/condition/outcome) in a given population at a designated time (e.g. asthma) - the numerator

Prevalence measures the frequency of “cases” of a disease (/condition/outcome) in a given population at a designated time (e.g. asthma) - the numerator

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Calculation of prevalence requires a suitable …

denominator (e.g. GP registered patients, schoolchildren) - the number of people who are ‘at risk’ of the disease

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Prevalence

Number of people who have disease at given time/ number of people at risk of having disease at given time

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Prevalence is expressed as either a …, a …. Or a … per unit of population

Prevalence is expressed as a percentage (e.g. 70%), a proportion of 1 (0.7 is equivalent), or a proportion per unit of population (700 of every 1000 people)

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Why might we be interested in prevalence of asthma?

Informing clinical diagnosis e.g. the more prevalent asthma, the more likely it is that this explains why the teenager is breathless…
Understanding the disease/condition and its risk factors (exposures) and outcomes e.g. identifying risk factors for breathless teenagers, identifying changes over time/place
Informing prevention and public health interventions e.g. educating teenagers/parents/public about asthma and its causes/consequences
Informing service planning and commissioning e.g. ensuring enough people/resources available to treat number of breathless teenagers

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Prevalence measures the frequency of … of a disease

“Cases” of a disease (/condition/outcome) in a given population at a designated time (E.g. asthma) - the numerator

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Types of prevalence (3)

Point, period, Lifetime

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Uses of different types of prevalence

Point and period - for better patient recall and tracking changes
Lifetime - short/fluctuating/episodic conditions

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What is point prevalence?

The proportion of a population that has the characteristic at a specific point in time

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What is period prevalence?

The proportion of a population that has the characteristic at any point during a given time period of interest

What is lifetime prevalence?

The proportion of a population who has ever had the characteristic at some point in their lifetime

Calculating prevalence:

Disease prevalence: Prevalence of disease = (A+C)/ N Prevalence of disease in exposed = A / (A+B) Prevalence of disease in unexposed = C / (C+D)

Exposure prevalence:

Prevalence of exposure = (A+B)/ N Prevalence of exposure in diseased = A / (A+C) Prevalence of exposure in non-diseased = B/ (B+D)

Cross-sectional study design - a defined population is surveyed to measure … … …

Cross-sectional study design - a defined population is surveyed to measure variable/s of interest (e.g. disease/outcome (E.g. asthma), exposure (E.g. sedentary lifestyle,sex)

In cross-sectional study, the sample is selected using …

Inclusion and exclusion criteria (Determined by study aims/research questions/hypotheses) - could be general population or clinic-based

Prevalence is reported for the sample and/ or subgroups based on … status

Prevalence is reported for the sample and/ or subgroups based on exposure status

Is the cross-sectional study descriptive or analytic?

Can be analytic or descriptive - Descriptive (about amount and distribution in population person, place and time) - Analytic (test hypotheses, identify or quantify risk or protective factors)

Strengths and weaknesses of cross-sectional studies

+ Can compare prevalence in exposed and non-exposed to risk factors Quick and inexpensive study type Can be used to initially explore/inform a hypothesis, prior to another type of study - Not suitable for rare diseases - Cannot separate cause (exposure) and effect (outcome) as they are measured at the same time - Cannot measure rate of new cases arising and any changes therein

Sources of cross-sectional study data?

Secondary - collected by someone else previously for a different purpose, then used by the researches in the specific study Primary - collected by the researches directly from main sources for the specific purpose

Examples of secondary cross-sectional data

Mortality registers, hospital/medical records, census data, previous research studies

Examples of primary cross-sectional study data?

Survey data

Pros of secondary cross-sectional study data

Cheap, if anonymous, minimal to no ethical/governance approval needed

Negatives of secondary cross-sectional study data

Limited by what data already gathered, poor accuracy and missing data

Pros of primary cross-sectional study data

Control over how variable/s of interest measured

Negatives of primary cross-sectional study data

More expensive and time-consuming, difficult to achieve representative sample

Research methods =

Foundational skills for evidence-based medicine

Prevalence = number of people with a condition in a defined … at a given … in time e.g. number breathless teenagers now

Prevalence = number of people with a condition in a defined population at a given point in time e.g. number breathless teenagers now

Examples of prevalence: What are the types? Current number of teenagers breathless now? Current number of teenagers breathless July-august 2020? Current number teenagers breathless ever in their lifetimes 2020?

Point – current number teenagers breathless now Period- current number teenagers breathless July-August 2020 Lifetime- current number teenagers breathless ever in their lifetimes 2020

Define prevalence

Number of people with a condition in a defined population at a given point in time

How to calculate prevalence

Prevalence = number with disease at given time / number at risk of disease at given time

What is a key study design to establish prevalence?

Cross-sectional study

Advantages vs Disadvantages of a cross-sectional study

Advantages – cheap, quick | Disadvantages – some issues with usefulness for establishing prevalence of rare or time-limited diseases

What does incidence measure?

Measures the frequency of “new onset cases” of a disease (/condition/outcome) (E.g. Covid-19) in a given population over a designated period of time (E.g. 12 months)

what studies don't need research ethics approval?

service evaluation service improvement quality improvement audit

when do studies need research ethics approval?

if patients or staff are involved

point prevalence

The number of cases of a specific condition or disorder that can be found in a population at one given point in time.

period prevalence

A measure of how many individuals were affected by the disease during a specified time period.

lifetime prevalence

the proportion of people in the population who have had a disease/exposure at some point over their lifetime

what are point and period prevalence better for?

better patient recall | better at tracking changes

what is lifetime prevalence better for?

tracking short, fluctuating or episodic conditions

cross-sectional study

A study in which a representative cross section of the population is tested or surveyed at one specific time to measure variable of interest

Pros of Cross-Sectional Studies

quick cheap can compare prevalence in exposed and non-exposed can initially form a hypothesis before another type of study

Cons of Cross-Sectional Studies

not good for rare exposures can't separate cause and effect can't measure incidence

descriptive study

a study designed to describe the amount and distribution of variables in populations

analytic study

an epidemiological study aimed at testing hypotheses, can identify and quantify risk

primary data sources

surveys, interviews, observation, community forums, focus groups

secondary data sources

mortality registers, medical records, census data, previous studies

Research Methods - Encountering evidence Flashcards

(62 cards)