9.4.11 Mortality Statistics

Interprets Mortality Statistics: Crude Death Rate, Death Rate, Mortality Rate, Age-Adjusted Death Rate, Standardized Mortality Ratio

Mortality statistics are commonly used to measure the frequency and pattern of deaths in a population. There are several different measures that can be used to interpret mortality data, including crude death rate, death rate, mortality rate, age-adjusted death rate, and standardized mortality ratio.

Crude Death Rate:

The crude death rate is the simplest measure of mortality, calculated by dividing the number of deaths in a given time period by the total population at risk during that time period. It is usually expressed as the number of deaths per 1,000 or 100,000 population. However, the crude death rate does not take into account the differences in age structure between populations, and therefore may not provide an accurate picture of mortality risk.

Death Rate:

The death rate, also known as the specific death rate, is calculated by dividing the number of deaths among a specific population by the total number of individuals in that population. It is expressed as the number of deaths per 1,000 or 100,000 population. This measure is useful for comparing mortality rates between different subgroups of a population, such as age groups or gender.

Mortality Rate:

The mortality rate, also known as the standardized death rate, takes into account the age structure of the population and adjusts for differences in age distribution between populations. This allows for a more accurate comparison of mortality rates between populations. It is usually expressed as the number of deaths per 1,000 or 100,000 population, standardized to a standard population.

Age-adjusted Death Rate:

The age-adjusted death rate is a type of mortality rate that adjusts for differences in age distribution between populations. It is commonly used to compare mortality rates between populations with different age structures. This measure is calculated by applying age-specific death rates to a standard population and then summing the results.

Standardized Mortality Ratio:

The standardized mortality ratio is a measure of the relative risk of mortality in a specific population compared to the general population. It is calculated by dividing the observed number of deaths in a specific population by the expected number of deaths based on the age and sex distribution of the general population. A standardized mortality ratio greater than 1 indicates an increased risk of mortality in the specific population, while a ratio less than 1 indicates a decreased risk.

Mortality Statistic	Definition
Crude death rate	The number of deaths in a population during a specified period of time per 1,000 or 100,000 people.
Death rate	The number of deaths in a specific population during a specified period of time is typically expressed as a rate per 1,000 or 100,000 people.
Mortality rate	The number of deaths in a specific population during a specified period of time is typically expressed as a rate per 1,000 or 100,000 people.
Age-adjusted death rate	A death rate has been standardized to a specific age distribution to allow for comparison across different populations.
Standardized mortality ratio	A measure of the ratio of the observed number of deaths in a population to the expected number of deaths based on the age and sex distribution of a standard population.

Overall, the interpretation of mortality statistics requires an understanding of the different measures used and the characteristics of the population being studied.

References:

1. Rothman KJ, Greenland S, Lash TL. Modern epidemiology. Lippincott Williams & Wilkins; 2008.