Measures of Mortality Dr. Asif Rehman

Measurements of Mortality Epidemiology: The study of the distributions and determinants of health related states or events in specified population and the application of this study to control health problems. (K Park, 20th edition)

Measurements of Mortality Specific objectives of epidemiology ? Cause of the disease Distribution/frequency of the problem Natural history and prognosis Evaluate both existing and new preventive and therapeutic measure and modes To provide foundation for developing public policy

Measurements of Mortality Mortality data: Traditionally and universally, most epidemiological studies begin with mortality data. Mortality data are relatively easy to obtain, and, in many countries, reasonably accurate. Many countries have routine systems for collecting mortality data. Each year information on deaths is analyzed and the resulting tabulations are made available by each government. Mortality data provide the starting point for many epidemiological studies. In fact, they are the major resource for the epidemiologist. (K Park, 20th edition)

Measurements of Mortality Uses of Mortality data: Statistics on causes of deaths are important and widely used for a number of purposes. They may be employed in explaining the trends and differentials in overall mortality. Indicating the priorities for health action and allocation of resources. Mortality data is helpful in designing intervention program, and in the assessment and monitoring of public health problems and programs. Moreover, they give important clues for epidemiological research.

Measurements of Mortality Mortality Rates and Ratios; Crude death rate Age specific mortality rate Cause specific mortality rate Case fatality rate Infant mortality rate Maternal mortality rate Proportionate mortality rate………………………etc

Measurements of Mortality Crude Death Rate: It is the number of deaths (from all causes) per 1000 estimated mid year population in one year, in a given place. It measures the rate at which deaths are occurring from various causes in a given population, during specified period. CDR = number of deaths (from all causes) during the year x 1000 mid year population (K Park, 20th edition)

Measurements of Mortality Population CDR Age specific death rates per 1000 populations 0-1 yrs 1-4 yrs 5-7 yrs 8-44 yrs 45-64 yrs 65+ yrs A 15.2 13.5 0.6 0.4 1.5 10.7 59.7 B 9.9 22.6 1.0 0.5 3.6 18.8 61.1

Measurements of Mortality Problem with CDR The limitations of the CDR is exposed when we compare the age- specific rates b/w the two populations. Population B has higher age-specific rates in all age group. This seeming contradiction is due to difference in the age composition of the population. The higher crude rate in population A is due to its older population compared with population B which has relatively younger population. Currently this is the prevailing situation in most developing countries with low crude death rates, but high age-specific death rates.

Measurements of Mortality Cause/Age specific death rate: When analysis is planed to throw a light on etiology, it is essential to use specific death rate. The specific death rates may be Cause or disease specific (TB, cancer, accident etc) Specific group (age, sex etc) CSDR = No of deaths from sp disease during calendar year X 1000 Mid year population (K Park, 20th edition)

Measurements of Mortality Case fatality rate: CFR represents the killing power of a disease. It is simply the ratio of deaths to cases. The time interval is not specified CFR is typically used in acute infectious diseases (Food poisoning, cholera, measles) CFR for the same disease may vary in different epidemics because of change in the agent, host and environment. CFR= Total no of deaths due to particular disease X 100 Total no of cases due to the same disease

Measurements of Mortality Infant Mortality rate The infant mortality rate is the ratio of deaths under 1 year of age in a given year to the total no of live births in the same year. IMR = No of deaths of children under 1 year of age X 1000 Total no of live births in the same year (K Park, 20th edition)

Measurements of Mortality Maternal Mortality rate Maternal deaths is defined as “the death of a women while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and site of pregnancy, from any causes related to or aggravated by the pregnancy or its management but not from accidental causes” MMR = Total no of female deaths due to complication of pregnancy, child birth or within 42 days of delivery from puerperal causes in an area during given year X 1000 Total no of live births in the same area and year

Measurements of Mortality MMR of different countries Country MMR Pakistan 270 per 100000 live births India 200 per 100000 live births USA 21 per 100000 live births UK 12 per 100000 live births Afghanistan 460 per 100000 live births

Measure of Mortality Proportionate mortality rate Survival rate Adjusted or standardized rate (Direct & indirect age standardization)

Exercise In an Asian country with a population of 6 million people, 60,000 deaths occurred during the year ending December 31st , 1995. These include 30,000 deaths from cholera in 100,000 people who were sick with cholera Calculate the case fatality rate from cholera in 1995 ? What was the cause specific mortality rate from cholera in 1995?

THANK YOU