Mortality Data and Health Indicators

Health Indicators

• Health indicators are classified into:
  • Mortality indicators
  • Morbidity indicators
  • Disability rates
  • Nutritional status indicators
  • Health care delivery indicators
  • Utilization rates
  • Indicators of social and mental health
  • Environmental indicators
  • Socioeconomic indicators
  • Health policy indicators
  • Indicators of quality of life
  • Other indicators

Mortality

• It is the condition of being mortal or susceptible to death, the opposite of immortality.

Limitation in mortality data

• Incomplete reporting of death
• Lack of accuracy and uniformity
• Choosing a single cause of death
• Changing coding system and changing fashion in diagnosis
• Diseases with low vitality

Uses of Mortality Data

• Explaining trends and differentials in overall mortality
• Indicating priorities for health action and allocation of resources
• Designing intervention programs
• Assessment and monitoring of public health problems and programs
• Giving clues for epidemiological research

Mortality Indicators

• Crude Death Rate is the number of deaths per 1000 estimated midyear population per year in a given community
  • It indicates the rate at which people are dying
  • Crude Death rate = (number of annual deaths / estimated mid-year population) x 1000
  • Population composition and age-specific death rates are factors
  • India’s death rate was estimated at 6.23 deaths/1,000 population in July 2009

Life Expectancy

• Life expectancy at birth is “the average number of years that will be lived by those born alive into a population if the current age-specific mortality rates persist”
  • It is estimated for both sexes separately
  • A good indicator of socioeconomic development in general
  • As an indicator of long-term survival, it can be considered a positive indicator
  • Can help to identify what is happening to overall standard of living
  • An Indian's average expected lifespan is:
    • Total population: 69.89 years
    • Male: 67.46 years
    • Female: 72.61 years (2009 est.)

Infant and Maternal Mortality Rate (IMR & MMR)

• Infant mortality rate is defined as “the ratio of infant deaths registered in a given year to the total number of live births registered in the same year;" which is expressed per 1000 live births
  • IMR= (number of deaths under 1-year age in 1 year / number of live births during that year) x 1000
  • India’s infant mortality rate is:
    • Total: 30.15 deaths/1,000 live births
    • Male: 34.61 deaths/1,000 live births
    • Female: 25.17 deaths/1,000 live births (2009 est.)

Neonatal Mortality Rate

• Calculated as number of deaths under 28 days of age occurred during a year / number of live births during that year x 1000

Maternal Mortality Rate

• Maternal death is the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and the site of pregnancy, from any cause related to or aggravated by the pregnancy or its management, but not from accidental or incidental causes
  • MMR = (number of female deaths from pregnancy, childbirth, or Puerperial causes in a year / number of live births in same area during that year) x 1000
  • A study of a decade found a change in trend in maternal mortality
    • The admission ledgers of patients admitted over two 3-year periods (1979-1981 and 1989-1991) were studied to ascertain the total number of maternal deaths and the specific causes of death

Fetal Death Rates

• The WHO subdivided fetal death based on gestation:
  • Early: under 20 weeks
  • Intermediate: 20 to 27 weeks
  • Late: 28 weeks and over
  • The stillbirth rate (late fetal death rate) correspond to
    • Stillbirth rate = (number of fetal deaths, 28 weeks of gestation or more occurred during a year) / (number of live births plus late fetal death during that year) x 1000
    • Late foetal death rate = (number of foetal deaths, 28 week of gestation Or more occurred during a year) / Number of live births during that year _x1000

Child Mortality Rate(Under 5 Mortality Rate)

• Defined as the number of deaths at ages 1-4 years in a given year, per 1000 children in that age group at the midpoint of the year concerned
  • Thus, excludes infant mortality

Child Survival Index

• A child survival rate per 1000 birth can be calculated by subtracting under 5 mortality rate from 1000, then dividing this figure by ten shows the percentage of those who survive to 5 years
  • Child survival rate = (1000 – under 5 mortality rate) / 10

Disease Specific Mortality

• Mortality rates can be computed for specific diseases
• As countries begin to extricate themselves from burden of communicable disease, a number of other indicators emerged as measures of specific disease problem

Proportional Mortality Rate

The simplest measure of estimating the burden of a disease in the community proportion of all death currently attributed to it. Proportional mortality rate for a specific disease = number of deaths from a specific disease / total deaths from all causes in that year x 100

Case Fatality Rate

• total number of deaths due to a particular disease / total number of cases with the same disease x 100
  • Determines the killing power of a disease
  • The ratio of death to case
  • Typically used in acute infectious diseases

Specific Mortality Rate

• Can be made specific with regard to any subgroup of the population
  • Age-specific death rate (group A)
    • no of death of age A in an year / Estimated population of age A midyear x 1000
  • Sex-specific death rate (sex M or F):
    • number of deaths of sex M in a year / estimated population of sex M midyear x 1000
  • Cause-specific death rate (cause C)
    • number of deaths due to cause C occurred / estimated midyear population x 1000
  • A refers to a specific age; C refers to specific cause of death; M and F refers to their gender

Adjusted or Standardized Rates

• If we want to compare the death rates of two populations with different age- composition, we can use 'age adjustment "or "age Standardization Direct and indirect standardization are two ways of computing standardized death rates
  • Direct Standardization (SDR₁)- calculates a weighted average of the region's age-specific mortality rates
    • SDR₁ = [Σ age groups (Mar Pas)]/Ps x 1000
      • Mar is the age-specific mortality rate for the region.
      • Pas is the number of people in the age group in the standard population.
      • Ps is the total standard population.
  • Indirect Standardization (SDR₂)-uses age-specific mortality rates from the standard population to derive expected deaths in the region's population
    • SDR₂ = Dr /[Σ age groups (Mas Par )] x CDRs
      • Mas is the age-specific mortality rate for the standard population
      • Par is the number of people in the age group in the region's population
      • Dr is the number of deaths in the region
      • CDRs is the crude death rate for the standard population

Morbidity

• Defined as "any departure, subjective or objective, from a state of physiological well being"
  • Equivalent to terms like sickness, illness, disability, etc.
  • WHO Expert Committee on Health Statistics noted morbidity measured in terms of 3 units
    • A person who is ill; the illness that these persons experienced; and duration of these illness.

Morbidity Data Summarization

• The nature and extent of disease load in the community is described, which assists in the establishment of priorities
• Provides comprehensive and accurate clinically relevant information on patient characteristics
• They act as starting points for aetiological studies and play a crucial role in disease prevention.
• Needs for monitoring and evaluation of disease control activities

Morbidity Indicator Use

• To describe health in terms of mortality is misleading as the mortality indicators do not reveal the burden of ill health-morbidity indicators are used to supplement mortality data to describe the health status of a population; mental illness and rheumatoid arthritis, for example. -Morbidity statistics also have their drawback; they tend to overlook a large number of conditions that are subclinical or inapparent, that is, the hidden part of the iceberg of disease

Following Morbidity Rates are Used for Assessing Ill Health in the Community

• Incidence and prevalence
• Notification rates
• Attendance rate at outpatient department, health centers, etc
• Admission readmission and discharge rates
• Duration in hospital and Spells of sickness or absence from work or school

Incidence

• Incidence rate is defined as "number of NEW cases occurring in a defined population during a specified period"
  • Calculation: number of new cases of specific disease / Population at risk during that period x1000
  • Applies only to new cases during a given period (usually one year) in a specified population or "population at risk."
  • It can also refer new spells or episodes of disease arising in a given period of time, per 1000 population Ex. if a person suffers from a common cold twice he would contribute two spells to the year.
    • Incidence rate formula = number of spells of illness occurring during a limited period / mean number of people exposed to danger that time x 1000

Prevalence

• Disease prevalence refers specifically to all current cases (old and new) existing at a given point of time, or over period of time in given population

Prevalence Indicator

• "Total number of all individuals who have an attribute or disease at a particular time (or during a particular period) divided by the population at risk of having the attribute or disease at this point in time or midway through the period"

Prevalence Types

• Point Prevalence

  • of a disease is defined as the number of all current cases (old and new) at a given point of time in relation to a defined population
    • can consist of day or a few weeks based on how long it takes to examine a population sample calculated as number of all current cases ,the old and the new, of a determined sickness that relates to a population at an allotted point in history / approximated populace at specified juncture multiplied by 100

• Period prevalence -A less commonly used measure of prevalence. - Measures the frequency of all current cases (old and new) existing during a defined period, expressed in relation to a defined population including cases arising before extending into or through to the year as well as those cases arising during the year - Existing number cases, new and old, of a definite illness within a time frame or span / Estimated central time populace at threat multiplied by 100

Relationship Between Prevalence and Incidence

• Prevalence depends on incidence and duration of illness
  • Assuming a stable population, unchanging incidence and duration, the relationship between incidence and prevalence can be expressed as:
    • P= I x D -incidence x mean duration

Prevalence Uses

• Helps estimate the magnitude of health/disease problems in the community and identify potential high-risk populations.
• Especially useful for administrative and planning purposes, (e.g. hospital beds, manpower needs, and rehabilitation facilities)