[1] Frequency Flashcards
In a Fraction of Proportions, What is the Numerator and What is the Denominator?
Numerator: Cases/Outcomes of Interest
Denominator: Population Examined or at Risk
Define: Prevalence
Proportion of a group of people possessing a condition at a particular time/period
Define: Point Prevalence
Proportion of cases (both old and new) at a single point in time
Define: Period Prevalence
Proportion of cases (both old and new) present during the given time interval
Define: Incidence
Proportion of the population at risk who develop the condition during a given time period
[Incidence vs. Prevalence]
Numerator Denominator Time Design Purpose
Incidence: New Cases Population at risk at the beginning of period Time interval Cohort study Causality
Prevalence: All cases Whole population Single point/Period Cross-sectional Association; Good for Diagnostic Test
What is the Relationship Between Prevalence and Incidence
Prevalence = Incidence x Average Disease Duration
Characteristic of Diseases with Long Duration with regards to Prevalence and Incidence
High Prevalence
Low Incidence
Characteristic of Highly Virulent Diseases with regards to Prevalence and Incidence
High Incidence Short Duration (Kills fast)
[Formula]
Average Disease Duration
Prevalence/Incidence
[Formula]
Case Fatality Rate
People who died within a period / # People with disease at start of the period
[Formula]
Complication Rate
People who develop complications / # People with disease at start of the period
[Formula]
Infant Mortality Rate
Deaths in a year of children <1 year old / # Live births in same year
[Formula]
Perinatal Mortality Rate
Fetal Deaths (>28 weeks AOG) + Neonatal Deaths (<7 days) / Fetal Deaths + Live Births
Define: Prevalence Study
Certain population is examined for the presence of the condition of interest at a certain cross-section in time
