Screening

Question 1

Types of screening

Answer 1

Selective: single (chest X-ray for miner,) mutiphasic (antenatal exams)

Mass screening: single disease (cervical cancers) mutiphasic (routine check ups for +75)

Opportunistic screening

Question 2

Selective screening

Answer 2

Identify individuals at high risk
Screen for early disease
Convert to low risk by behaviour modification and or intervention

Question 3

Benefits of selective screening

Answer 3

Preventative measure
Less radical intervention
Reduced cost
Reduced morbidity and mortality

Question 4

Sensitivity def

Answer 4

The probability that the test will be positive if the disease is truly present. a/(a+c)

Question 5

Specificity def

Answer 5

The probability that the test is negative if the disease is truly absent. d/(b+d)

Question 6

What disease suitable for screening?

Answer 6

Slow progressive natural history
Early therapy gives better results than late therapy
High prevalence
Disease effects major

Question 7

UK national screening principles

Answer 7

Natural history understood 
Condition is an important problem
Accepted treatment
Benefits outweigh harm
Enough staff and facilities for treatment 
Agreed policy on who to treat

Question 8

Positive predictive value of test

Answer 8

The probability of truly having the disease if the screening test is positive. a/(a+b)

Question 9

Negative predictive value of test

Answer 9

The probability of being disease free when the screening test is negative. d/(c+d)

Question 10

Screening def?

Answer 10

Process of identifying unrecognised conditions by rapidly applied tests on a large scale.