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