Epidemiology and Screening Disease

appropriate situations for screening tests

-condition screened needs to be important -screening test should have a high cost-benefit ratio -condition needs to be sufficiently prevalent -an effective treatment should be available

2 controversies regarding screening tests

-false alarms false positive results are disconcerting for patients who receive them -possible over diagnosis of potentially benign conditions

measures used in screening

-reliability -validity

realiability versus validity

-what a screening test should be -interrelated terms

policy issues and screening for disease

-who should be screened -what conditions should be screened -underwhich circumstances should screening tests be used -at what age should screening begin

gold standard

a definitive diagnosis that has been determined by biopsy surgery autopsy or other method

selective screening

a type of screening applied to high risk groups such as those at risk for sexually transmitted disease

true negatives

are individuals who both have been screened negative and do not have the conditions

true positives

are individuals who both have been screened positive and truly have the condition

false negatives

are individuals who have been screened negative and who truly have the condition

false positives

are individuals who have been screened positive but do not have the condition

definition of screening

as the presumptive (likely) identification of disease or defects by the application of tests, examinations, or other procedures that can be applied rapidly

the two types of screening

mass screening selective screening

overview of screening

overall role in health promotion control of major chronic diseases protection of the public controversies policy issues

mass screening

refers to application of screening tests to total population groups, regardless of their risk status

reliability aka precision

refers to the ability of a measuring instrument to give consistent results on repeated trials

screening tests need to demonstrate

reliability validity

selective screening likely to

result in the greatest yield of true cases and to be the most economically efficient

validity aka accuracy

the ability of the measuring instrument to give a true measure of the entity being measured gold standard