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

1. Crude Death Rates

2. 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.

Thank You