1. Screening and Prevention

2. Prevention Can be classified into three types: Primary Secondary
Tertiary

3. Primary Prevention
Removing the cause
Sanitation
Passive smoking

4. Secondary Prevention
Identify presymptomatic disease before damage is done
Examples?
Blood pressure
Diabetic screening

5. Tertiary Prevention
Limiting complications and disability in established disease by regular surveillance
Examples?
Diabetic Retinopathy Screening

6. Methods of Screening Case Finding True screening
opportunistic or anticipatory
True screening
What are the pros and cons of each?

7. Wilson’s Criteria Condition must be: Screening must be: common
important
diagnosable
have a latent interval
Screening must be:
cheap and simple
continuous
targeted towards a high risk group

8. Wilson’s Criteria
Although the following were not part of Wilson’s original criteria we might add:
Disease readily treatable
Tests sensitive, specific, safe, acceptable and easy to interpret
Benefits outweigh costs

9. The Test Explain the following terms: Sensitivity Specificity
few false negatives
Specificity
few false positives
Positive Predictive Value
likely to be correct when positive

10. The Test Discuss the trade off between sensitivity and specificity
What happens if the prevalence is low?
even test of high sensitivity and specificity have a low predictive value
Do we move the point of death?
Imperfect knowledge of natural history of the condition causes what problems?

11. Benefits of Screening Improved mortality Improved morbidity
Possible savings on costs of future treatment

12. Costs of Screening Patients: Doctors NHS anxiety false reassurance
economic
Doctors
NHS

13. Obstacles to Prevention
Discuss the obstacles to prevention from:
patients
doctors
NHS

14. Overcoming Patient Obstacles
Point out debits
Point out benefits
Anticipate and discuss difficulties
Suggest coping stategies
Simple advice and written information