Mortality refers to death and related issues. There are several ways to measure and compare mortality rates in different populations. Crude mortality rates provide the total number of deaths per population over a period of time but do not account for differences in age or sex. Specific mortality rates, like infant mortality rates, measure deaths from a particular cause or in a specific age group. Adjusted mortality rates like standardized mortality ratios allow for comparisons between populations while controlling for certain variable differences.
8. 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
9. Proportions
• Compare like populations or like
illnesses within a population
For example, 40 children are currently
ill with measles, while 80 children all
together have or have had the measles
12. 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
13. Three Levels of Rates
• Crude rates
• Adjusted rates
• Specific rates/ratios
14. 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
15. 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
29. Adjusted Death Rates
• Allows comparisons by controlling
for differences in some variables
Standardized 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
39. Other Issues Related to Mortality
• Mortality Cross-over
Death 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