It is impractical to perform all possible screening procedures

 Within a population, it is certainly impractical to perform all possible screening procedures for the variety of diseases that exist in that population. This approach would be overwhelming to the medical community and would not be cost-effective. Indeed, the amount of monetary and psychological stress that would occur from pursuing false-positive test results would add an additional burden on the population. When determining which procedures should be considered as screening tests, a variety of end points can be used. One of these is to determine how many individuals would need to be screened in the population to prevent or alter the outcome in one individual with disease. While this can be statistically determined, there are no recommendations for what the threshold value should be, and may change based on the invasiveness or cost of the test and the potential outcome avoided. Additionally, one should consider both the absolute and relative impact of screening on disease outcome. Another measure used in considering the utility of screening tests is the cost per life-year saved. Most measures are considered costefective if they cost <$30,000–$50,000 per year of life saved. This measure is also sometimes adjusted for the quality of life as well and presented as quality-adjusted life-years saved. A final measure that is used in determining the effectiveness of a screening test is the effect of the screening test on life expectancy of the entire population. When applying the test across the entire population, this number is surprisingly small, and a goal of about 1 month is desirable for a population-based screening strategy