Prevention and screening Flashcards

1
Q

What criteria used for screening?

A

Wilson and Jungner criteria

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2
Q

Types of prevention and example of each?

A

Primary - Prevent onset of disease (exercise more, eat well)
Secondary - Early identification of disease and prevent disease from worsening (QRisk and statin administration)
Tertiary - Rehab following significant illness (medication post-MI +/- PCI)

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3
Q

What is the definition of screening?

A

A process which sorts out apparently well people who probably have a disease from those who probably do not.

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4
Q

Types of screening?

A
Population-based screening programmes
Opportunistic screening
Screening for communicable diseases
Pre-employment and occupational medicals
Commercially provided screening
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5
Q

What are some of the Wilson and jungner criteria?

A

The condition:
Important health problem
Latent / preclinical phase
Natural history known

The screening test:
Suitable
Acceptable

The treatment:
Effective
Agreed policy on who to treat

The organisation and costs:
Facilities
Costs and benefits
Ongoing process

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6
Q

Define sensitivity

A

the proportion of people with the disease who are
correctly identified by the screening test

Sensitivity = No. of true positives/(no. of true positives + false negatives)

High sensitivity ideal for contact tracing purposes in a pandemic

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7
Q

Define specificity

A

the proportion of people without the disease who are
correctly excluded by the screening test

Specificity= No. of true negatives/(no. of true negatives+ false positives)

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8
Q

Define positive predictive value

A

the proportion of people with a positive test

result who actually have the disease

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9
Q

Define negative predictive value

A

the proportion of people with a negative

test result who do not have the disease

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10
Q

Difference between predictive values and sensitivity/specificity?

A

Predictive values based on underlying prevalence. Sensitivity and specificity are not.

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11
Q

Type of bias in screening?

A

Lead-time bias (Screened patients have same survival rate as those not screened)
Length-time bias (less aggressive cancers more likely to be picked up from screening compared to more aggressive cancers –> hence die later)

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