Presentation on theme: "Screening and Prevention. Prevention Can be classified into three types: Primary Secondary Tertiary."— Presentation transcript:
Screening and Prevention
Prevention Can be classified into three types: Primary Secondary Tertiary
Primary Prevention Removing the cause Sanitation Passive smoking
Secondary Prevention Identify presymptomatic disease before damage is done Examples? Blood pressure Diabetic screening
Tertiary Prevention Limiting complications and disability in established disease by regular surveillance Examples? Diabetic Retinopathy Screening
Methods of Screening Case Finding –opportunistic or anticipatory True screening What are the pros and cons of each?
Wilsons Criteria Condition must be: –common –important –diagnosable –have a latent interval Screening must be: –cheap and simple –continuous –targeted towards a high risk group
Wilsons Criteria Although the following were not part of Wilsons original criteria we might add: –Disease readily treatable –Tests sensitive, specific, safe, acceptable and easy to interpret –Benefits outweigh costs
The Test Explain the following terms: –Sensitivity few false negatives –Specificity few false positives –Positive Predictive Value likely to be correct when positive
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?
Benefits of Screening Improved mortality Improved morbidity Possible savings on costs of future treatment