Researchers were interested in determining if lifestyle modi…

Researchers were interested in determining if lifestyle modification can reduce the incidence of a second heart attack (myocardial infarction). They identified a group of 700 patients who had a first (single) heart attack within the past five years.  These patients were then randomly allocated to: 1) a lifestyle intervention group (n=350) that received intensive dietary and physical activity counseling and training; or 2) a comparison group (n=350) that received only some educational information regarding the benefits of healthy lifestyles in reducing heart disease. These groups were then followed for 5 years to determine the rates of second heart attacks.  The researchers could use a triple masked (blind) study design

Policies, procedures, and threshold levels of a screening te…

Policies, procedures, and threshold levels of a screening test should be determined in advance to establish who should be referred for further testing, diagnostics and possible treatment. Once these are determined in at least one study population, the screening test can be administered on any population in the world.