Number of deaths occurring in a given population at risk during a specified time period (also known as the recall period).

Usually expressed as deaths per 1000 persons per month or per year.

Usually expressed as deaths per 1000 persons per month or per year.

World Health Organization. Definitions. 2009.

An estimate of the proportion of a population that dies during a specified period.

The*numerator* is the number of persons dying during the period; the *denominator* is the total number of people in the population, usually estimated as the mid-year population.

This rate is an estimate of the person-time death rate, i.e., the death rate per person-years.

This rate is also called the*crude death rate*.

The

This rate is an estimate of the person-time death rate, i.e., the death rate per person-years.

This rate is also called the

World Health Organization. Definitions of terms. 2009.

A mortality rate (MR) expresses the number of events (deaths) that occur in a population of known size that is at risk for the death event during a specific period of time (usually called the recall period).

Mortality rate = Total deaths during period / (mid-period population at risk x duration of period)

The mid-period (or mid-point) population is estimated by (i) taking the population at the end of the period; (ii) adding one half of the deaths during the period; and (iii) subtracting one half of the births during the period.

__Example.__

- duration of period: 120 days

- births during period: 360

- population at end: 18,300

- deaths during this period: 445

Mid-period population at risk: 18,300 + 0.5(445) – 0.5(360) = 18,343

Unit of expression: per 10,000 people per day

MR = [445 / (18,343 x 120 days) ] x 10,000 = 2.02 deaths per 10,000 people

*Interpretation. In this population, on average about 2 people out of 10,000 died every day during the 120-day period analysed.*

Mortality rate = Total deaths during period / (mid-period population at risk x duration of period)

The mid-period (or mid-point) population is estimated by (i) taking the population at the end of the period; (ii) adding one half of the deaths during the period; and (iii) subtracting one half of the births during the period.

- duration of period: 120 days

- births during period: 360

- population at end: 18,300

- deaths during this period: 445

Mid-period population at risk: 18,300 + 0.5(445) – 0.5(360) = 18,343

Unit of expression: per 10,000 people per day

MR = [445 / (18,343 x 120 days) ] x 10,000 = 2.02 deaths per 10,000 people