Study Design and Measures of Disease Frequency Intermediate Epidemiology
Objectives To discuss Kaplan Meier survival curves To discuss different types of rates that are commonly used in epidemiology
Absolute measures of Disease Frequency MeasureExpressesTypes of Events IncidenceFrequency of a new event New or recurrence of a disease Death Development of a side effect PrevalenceFrequency of an existing event Point Period Cumulative
Incident Rate
Prevalence Rate
Period Prevalence
Mortality Rates
Cause-specific mortality rates
Case-fatality rate
Infant Mortality Rate Special Mortality rates Neonatal = under age of 28 days Post-neonatal = 28 days to 11 months
Age-specific mortality rates The number of deaths in a specific age group during a specified period of time ____________________________________ The total number of individuals in that same age group During the same period of time Example: Homicides among year olds in New Orleans for 1994 ___________________________________ The number of persons aged in New Orleans In `994
Fetal Death Rate
Crude Birth Rate
Fertility Rate
Survival Rate
Other measures Ratio - expresses a relationship between two quantified measures (i.e.male:female) Proportion - types of ratios where the numerator is included in the denominator –PMR - indicates the relative importance of specific causes of death to the total number of deaths in a specific population (expressed as a percentage)