2 Prevention Can be classified into three types: Primary Secondary Tertiary
3 Primary PreventionRemoving the causeSanitationPassive smoking
4 Secondary PreventionIdentify presymptomatic disease before damage is doneExamples?Blood pressureDiabetic screening
5 Tertiary PreventionLimiting complications and disability in established disease by regular surveillanceExamples?Diabetic Retinopathy Screening
6 Methods of Screening Case Finding True screening opportunistic or anticipatoryTrue screeningWhat are the pros and cons of each?
7 Wilson’s Criteria Condition must be: Screening must be: common importantdiagnosablehave a latent intervalScreening must be:cheap and simplecontinuoustargeted towards a high risk group
8 Wilson’s CriteriaAlthough the following were not part of Wilson’s original criteria we might add:Disease readily treatableTests sensitive, specific, safe, acceptable and easy to interpretBenefits outweigh costs
9 The Test Explain the following terms: Sensitivity Specificity few false negativesSpecificityfew false positivesPositive Predictive Valuelikely 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 valueDo 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