Mortality rates and migration

The Mortality Rates

Learning objectives:
Study Factors affecting Population Dynamics:
Mortality Rates
Migration

Mortality Rates

A mortality rate is a measure of the frequency of occurrence of death in a defined population during a specified period of time.


1. Crude mortality rate (crude death rate)

The crude mortality rate is the mortality rate from all causes of death for a population.
For 10n, we usually use 1000. = Deaths/1000 individual in the specified year and locality.


Total No. of deaths in a certain year & locality
Crude Death Rate = ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ X 1000
Estimated mid-year population (same year & locality)



It is important to use the population size at the midpoint of t he time interval as an estimate of the average population at risk especially if
a denominator population is growing or shrinking during the period of time for which a rate is to be computed.
e.g. If a death rate is to be calculated for the year 2000, then the population of July 1, 2000 is used for the denominator.

2. Age (sex..category) -specific mortality rate

An age-specific mortality rate is a mortality rate limited to a particular age group.
The numerator is the number of deaths in that age group(or any category)
The denominator is the number of persons in that age group or category in the population.

No. of persons dying in a certain age & a certain year and area

= ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ X 1000
Total No. in the same age group in the same year & same area

Sex-specific mortality rate

A sex-specific mortality rate is a mortality rate among either males or females.
Both numerator and denominator are limited to the one sex.

Total No. of deaths of certain sex during a year in a given locality

= ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ X 1000
Total No. of the same sex during the same year & locality


3. Cause-specific mortality rate

The cause-specific mortality rate is the mortality rate from a specified cause for a population.
The numerator is the number of deaths attributed to a specific cause.
The denominator remains the size of the population at the midpoint of the time period.

Death of a specific cause in a given year & locality
= ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــX 100,000
Estimated mid-year population in same year & locality

Example of cause specific death rates:

No. of deaths of TB in a certain year & locality
Specific death rate due to TB = ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ X 100,000
Estimated mid-year population in same year & locality

4. Proportionate mortality

Deaths due to a particular case
Proportionate mortality = ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ X 100
Deaths from all causes


5. Case fatality rate (Death to case ratio)

Total No. of deaths from a certain disease in a year & in a given locality

= ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ X 100
Total No. of cases having the same disease in the same year & locality

This rate can be used for measuring the virulence of the agent of the disease

6. Other rates
a. Infant mortality rate:
The infant mortality rate is one of the most commonly used measures for comparing health services among nations.
The numerator is the number of deaths among children under 1 year of age reported during a given time period, usually a calendar year.
The denominator is the number of live births reported during the same time period.
The infant mortality rate is usually expressed per 1,000 live births.
In 1988, infant mortality rate in the United States was 9.9 per 1,000


Total No. of deaths aged from Zero to ( 1 year during a year & in a given locality
= ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ X 1000
Total No. of live births in the same year & locality


b. Neonatal mortality rate:
The neonatal period is defined as the period from birth up to (but not including) 28 days.
The numerator of the neonatal mortality rate is the number of deaths among children under 28 days of age during a given time period.
The denominator of the neonatal mortality rate, like that of the infant mortality rate, is the number of live births reported during the same time period.
The neonatal mortality rate is usually expressed per 1,000 live births.
In 1988, the neonatal mortality rate in the United States was 6.3 per 1,000 live births.

c. Postneonatal mortality rate

The postneonatal period is defined as the period from 28 days of age up to (but not including) 1 year of age.
The numerator of the postneonatal mortality rate therefore is the number of deaths among children from 28 days up to but not including 1 year of age during a given time period.
The denominator is the number of live births reported during the same time period.
The postneonatal mortality rate is usually expressed per 1,000 live births.
In 1988, the postneonatal mortality rate in the United States was 3.6 per 1,000 live births
What is the ratio of neonatal to postneonatal mortality?
Compare it between developed and developing countries?

d. Perinatal Mortality Rate

It is expressed as the sum number of still births and early neonatal deaths (less than 7 days of life) per 1000 total births (still births plus live births).
 EMBED Equation.3 










6. Maternal mortality rate (ratio)

The maternal mortality rate is really a ratio used to measure mortality associated with pregnancy.
The numerator is the number of deaths assigned to causes related to pregnancy during a given time period.
The denominator is the number of live births reported during the same time period.
Because maternal mortality is much less common than infant mortality, the maternal mortality rate is usually expressed per 100,000 live births.
In 1988, the maternal mortality rate was 8.4 per 100,000 live births.


Maternal mortality rate** =
Number of deaths among women due to Pregnancy (usually per 100,000) Delivery and/or Puerperium in one year
Number of live births in that year

Combinations of specific mortality rates

Different combinations of specific mortality rates can be calculated e.g. cause-specific, age-specific,
For example, the mortality rate attributed to HIV among 25- to 44-year-olds in the United States in 1987 was 9,820 deaths among 77.6 million 25- to 44-yearolds, or 12.7 per 100,000.
This is a cause- and age-specific mortality rate, because it is limited to one cause (HIV infection) and one age group (25 to 44 years).

Rates whose denominators are total population:

Crude mortality rate (crude death rate)
Crude Birth rate (crude Birth rate)
Cause-specific mortality rate


Rates whose denominators are total population:
Infant mortality rate
Neonatal mortality rate
Postneonatal mortality rate
Maternal mortality rate

Migration

Definition: Migration is the movement of populations across a specified boundary for the purpose of residing. Migration is the change of residence of a person or group of persons for better life and higher standard of living.
The terms immigration and emigration are used to refer to movement between countries (international migration). The parallel terms: in - migration and out-migration are used for internal movement between different areas within a country (internal migration).

Types of migration

I- Internal migration
It is the movement within the boundaries of a given country.
Examples of Egyptian internal migration:
1 - Rural - Urban migration.
2 - Movement of nomads.
3 - Movement of temporary and seasonal nature.
4 - Movement between and within urban areas.

II- External migration

a) Permanent migration:
An example is the permanent movement of Egyptians to the U.S.A., Australia and Canada (about two millions).


b) Temporary migration:
It is the migration over the borders of one society to another for the aim of working for a number of years, with the intent of an eventual return to the motherland. An example is the migration of Egyptian professionals and laborers to Arab Countries. In 1980, the percentage of Egyptians working in Arab Countries was 3.4% of the total population. In 2000, they totaled two millions.
Although migration affects the characteristics of the population, its role is minimal when compared to fertility and mort









Al Kindy College of Medicine

Community Medicine Department Lab. 5 Practical Lab. Of General Epidemiology

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Perinatal death

Infant death


Post neonatal death

Still birth

Abortion

Early neonatal death

Late neonatal death

Neonatal death