Mortality Rates and Indices

Incidence vs. Prevalence

• Incidence measures the rate at which new cases of a disease occur in a population over a specified period.
• Prevalence reflects the total number of existing cases (new and old) of a disease at a specific time, indicating the overall disease burden.

Key Differences

• Incidence is ideal for tracking chronic diseases and is calculated via follow-up studies.
• Prevalence is broader and often used for both acute (communicable) and chronic diseases.
• Incidence indicates disease emergence, while prevalence shows how widespread the disease is in the population.

Mortality Indices

• Crude Death Rate (CDR): Number of deaths in a year per 1,000 midyear population.
  • Influenced by socioeconomic factors, disease patterns, age structure, and health system effectiveness.

Age-Specific Death Rates

• Special categories include:
  • Neonatal Mortality Rate (NMR): Deaths in infants <4 weeks per 1,000 live births.
  • Infant Mortality Rate (IMR): Deaths in children <1 year per 1,000 live births.
  • Under-5 Mortality Ratio (U5MR): Deaths of children <5 years per 1,000 live births.

Cause-Specific Mortality Rate

• Measures deaths from a specific disease per 100,000 population.
• Proportionate Death Rate: Percentage of total deaths due to a specific cause.
• Case Fatality Rate: Percentage of cases leading to death from a disease within a certain timeframe.

Maternal Mortality Ratio

• Defined as the number of maternal deaths related to pregnancy per 100,000 live births over a specific time period.

Decrease in Incidence Rates

• May result from:
  • Enhanced population resistance to diseases.
  • Changes in disease etiology.
  • Effective public health and prevention programs.

Overall Health Implications

• Understanding the differences and implications of incidence and prevalence is critical in public health, epidemiology, and the formulation of health policies aimed at disease control and prevention.