Screening

Question 1

Criteria needed before implementing population screening

Answer 1

1. Condition should be important health problem
2. Accepted treatment for os with recognised disease
3. Facilities for diagnosis and treatment available
4. Recognisable latent/early symptomatic stage
5. Suitable test/examination
6. Test is acceptable to population
7. Natural history of condition should be understood
8. Agreed-upon policy in whom to treat as patients
9. Cost-benefits balanced
10. Case-finding should be continuous project

Question 2

Lead time bias

Answer 2

Appearance that early diagnosis due to screening falsely prolonged survival with disease

Question 3

Length bias

Answer 3

Overestimation of survival duration due to excess of cases detected that asymptomatically slowly progress, while fast progressing cases are detected after giving symptoms

Question 4

Benefits of screening

Answer 4

Earlier diagnosis
May improve prognosis for those who develop disease
May increase prevention of disease
May save Monet if early treatment is cheaper

Question 5

Disadvantages of screening

Answer 5

Screening programmes cost money
Induce anxiety in the well
May harm directly 
Will not detect all diseases
Screen negative - delay in presenting symptomatic disease if falsely reassured
False positives
Over-diagnosis