3 Measurement of mortality
Measurement of Mortality
Dr. Hiba Elzaki, Assistant Professor at Gulf Medical University, Ajman, UAE
Learning Objectives
Describe differences between various mortality measures.
Compare applications of each measure of mortality.
Mortality Statistics
Mortality statistics are a key health indicator.
Coverage of birth and death registration varies globally.
Sources of Mortality Data
Vital statistics registration (birth and death records)
National surveys
Specific health surveys
Hospital records
Notification of diseases
Uses of Mortality Data
Indicates overall health status of a population.
Identifies leading causes of death and mortality patterns.
Monitors and assesses health program impacts.
Mortality Rate
Definition: Frequency of death occurrence in a defined population over a specified time period.
Calculation of Mortality Rate
Formula:
Deaths occurring during a given time period x 10
Size of the population among which the deaths occurred.
Common denominators: 1,000 and 100,000.
Frequently Used Measures of Mortality
Crude Death Rates
Specific Death Rates
Crude Death Rate (CDR)
Definition: Number of deaths from all causes within a population over a year.
Formula: No. of deaths x 10
Mid-year population.
Example Calculation of Crude Mortality Rate
Total deaths = 2,419,921
Estimated population = 290,809,777
Calculation: CDR = (2,419,921 / 290,809,777) x 100,000 = 832.1 deaths per 100,000 population.
Uses of Crude Death Rate
Measures population decrease due to deaths.
Provides rough risk of dying for the population.
Useful for year-to-year comparisons in the same area.
Disadvantages of Crude Death Rate
Cannot compare populations with different age structures.
Age-Adjusted Mortality Rates
Statistical techniques adjust rates to correct for age distribution differences.
Results in age-adjusted mortality rates for accurate comparisons.
Specific Death Rates
Cause-specific death rate: Death rate attributed to a specific cause.
Age-specific death rate: Death rate in a specific age group.
Includes neonatal, infant, maternal mortality rates and case fatality rates.
Cause-Specific Mortality Rate
Defined: Mortality rate from a specified cause in a population.
Calculation: Number of deaths attributed to a specific cause
Midpoint population size, expressed per 100,000.
Calculation Example of Cause-Specific Mortality Rate
Total deaths from accidents = 108,256
Result: Cause-specific mortality rate = 37.2 per 100,000 population.
Disease-Specific Death Rates
Definition: Number of medically certified deaths due to a specific disease in a year.
Calculation: No of deaths x 10
Mid-year population of the same year.
Age and Sex-Specific Death Rates
Definition: Total deaths in a specific age/sex group during a defined period
Population of same group in the same area.Provides insights on mortality risks in specific demographic groups.
Age-Specific Mortality Rate
Limited to a particular age group.
Calculation: Number of deaths in age group
Number of persons in that age group.Example: 130,761 deaths among 25-44-year-olds results in a mortality rate of 153.0 per 100,000.
Infant Mortality Rate (IMR)
Definition: No of deaths under one year of age in a year
Number of live births in the same year.Importance: IMR reflects overall health conditions and is affected by maternal health, quality of healthcare, socioeconomic conditions, and public health practices.
Neonatal Mortality Rate (NMR)
Calculation: Number of deaths under 28 days of age during a year
Live births during the same year.
Maternal Mortality Rate (MMR)
Definition: Deaths among women during pregnancy, delivery, or within 42 days of pregnancy termination
Live births in the same year.
Case Fatality Rate
Proportion of persons with a condition who die from it.
Indicator of the severity of a disease.
Formula: Total deaths from disease
Total cases of the disease x 100.
Example Case Fatality Rate Calculation
Epidemic of hepatitis A: 555 cases, 3 deaths.
Calculation: Case-fatality rate = (3 / 555) x 100 = 0.5%.
Limitations of Mortality Measures
Data Quality: Inaccuracies can result in biased outcomes.
Population Changes: Aging demographics can lead to misleading CDRs.
External Factors: Various socio-economic and environmental factors can influence mortality.
Errors and Limitations in Mortality Statistics
Under-reporting of deaths.
Inaccuracies in death certification due to lack of medical facilities and large unreported deaths.
Factors Affecting Mortality Rates
Access to healthcare and quality of services.
Socioeconomic conditions and living standards.
Public health interventions and policies.
Environmental factors and lifestyle choices.
Genetic predispositions and demographics.
Conclusion
Mortality measures serve as essential public health tools.
Timely and accurate data is crucial for effective interventions.
Addressing limitations is vital for better data quality and interpretation.