Likelihood Ratio (LR): odds of a positive test in patients with the disorder compared with those without the disorder = sensitivity / (1 -specificity)
Incidence and Prevalence
Incidence: number of new cases occurring in a population over a given period of time (month, year, etc)
Prevalence: number of current cases per population (example: number of cases per 10,000 people)
Point Prevalence: proportion of a population that has the condition at a specific point in time
Period Prevalence: proportion of a population that has the condition at some time during a given period (example: 12-month prevalence), and includes people who already have the condition at the start of the study period as well as those who acquire it during that period
-Lifetime Prevalence: proportion of a population that at some point in their life (up to the time of assessment) have experienced the condition
Risk Reduction
Example Data Set from National Lung Screening Research Trial [MEDLINE]
National Lung Screening Research Trial Team: Reduced lung-cancer mortality with low-dose computed tomographic screening. N Engl J Med 2011;365:395-409 [MEDLINE]
