measures of mortality & mortality in different populations
Post on 18-Dec-2015
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Rates
• With rates, the numerator is included in the denominator
• Rate is the number of or frequency of a disease per unit size of population
Ratios
• Ratio – the relation in number, degree or quantity existing between two similar things
25 ♀ : 30 ♂
• Ratio as a fraction
25/30 or 5/6
Proportions• Compare like populations or like
illnesses within a populationFor example, 40 children are currently
ill with measles, while 80 children all together have or have had the measles
Mortality
• Deaths; describes death; related issues
• Graunt 1600s – Bills of Mortality
• Farr (1807-1883) Registrar general; vital statisticsCausesRegistration
Types of Mortality Rates/Ratio• annual death rate• crude death rates• infant mortality rates (ratio)• neonatal mortality rates• postneonatal mortality rates• perinatal mortality rates• fetal death rates• fetal death ratios• abortion rates• maternal mortality rates• adjusted mortality rates• standardized mortality ratio• specific death rates• proportionate mortality rate- case fatality rate• mortality crossover – mortality time trends
Your Assignment: familiarize yourself with the definitions
of these terms
Annual Death Rates• “General” (crude) mortality rate
a population group exposed to risk of death
a time period
• Crude Mortality Rate = # of deaths occurring in that population during that period of time
Crude Death Rates• Does NOT account for differences of
age, sex, etc. in any aspect of death
• Info needed: total deaths total population a given period of time
Adjusted Death Rates• Allows comparisons by controlling
for differences in some variablesStandardized Mortality Ratio (SMR)Proportionate Mortality Ratio (PMR)Specific Mortality Rates
• Does NOT account for differences of age, sex, etc. in any aspect of death
• Info needed: total deaths total population a given period of time
Other Issues Related to Mortality
• Mortality Cross-overDeath of a subject that started in one group
but “crossed over” to another group during course of study
• Mortality Time Trends
• Years of Potential Life Lost (YPLL)YPLL Rate