Measurements of Health Status

So, is there any way we can tell how healthy a person or group is, and compare their levels of health?  Yes!

Health status is an individual’s or population’s overall level of health, taking into account various aspects such as life expectancy, amount of disability and levels of disease risk factors.

An individual’s health status is usually measured by a health professional, whereas we measure population health status using statistics and data presented as a set of measurements or ‘indicators’, including:

  • life expectancy
  • health-adjusted life expectancy
  • morbidity
  • mortality
  • under-five mortality
  • burden of disease
  • DALYs
  • incidence
  • prevalence

Remember that each measurement has its limitations, and is best used in particular circumstances.

Life Expectancy

Life Expectancy (LE) is an indication of how long a person can expect to live.  It is the number of years of life remaining to a person at a particular age (such as 30, 65 or 85, but most commonly at birth) if current death rates do not change.

Health Adjusted Life Expectancy (HALE) is a measurement burden of disease based on life expectancy at birth, but including an adjustment for time spent in poor health.  It’s the number of years a person can expect to live in good health, if current morbidity and mortality rates don’t change.  So while it’s similar to LE, it is a more comprehensive measure of health status as it focuses on quality of life, not just years of life.

Morbidity and Mortality

Mortality is the number of deaths caused by an illness, disease or external factor.

Morbidity is the occurrence of disease or illness in an individual or population. It is less reliable than mortality data (death is conclusive, illness can be subjective and difficult to measure).

Under 5 Mortality Rate (U5MR) is the number of deaths of children under the age of five, per 1000 live births.  It is commonly used as it demonstrates a population’s levels of education, economic development and healthcare.

Burden of Disease

Burden of disease measures the impact of diseases and injuries, in a way that morbidity and mortality can’t.  For example:

Morbidity measures the number of people with Type 1 diabetes in a population, and mortality measures the deaths due to it, but fails to show how much the suffering from the condition impacts health and quality of life.

Burden of disease, however, attempts to calculate this impact. Specifically, it measures the gap between the current health status and the ideal situation, where people live long lives free of disease. It measures this through a unit called a DALY – a disability-adjusted life year.

One DALY is one healthy year of life lost due to premature death or time lived with illness, disability or disease.  The more DALYs a population has for a certain condition, the higher the burden of disease the population is experiencing; it’s not just how many are suffering, but how much they are suffering.

One DALY can either be a YLL (a Year of Life Lost due to premature death – fatal) or a YLD (Year Lost to Disability – non-fatal).  High YLL levels occur with diseases which kill quickly, while high YLD levels occur with conditions like mental illnesses, which have low fatality levels, but cause people to suffer from disability for many years.

Incidence and Prevalence

Incidence is the number or rate of new cases of a disease or condition in a population over a given time period.

Incidence can be useful in assessing health promotion campaigns, as a decrease in new cases may suggest that fewer people are developing the disease due to the campaign. Increases in incidence are not always bad, however, as screening tests can help uncover new cases of disease which would otherwise have gone undetected, and so a spike in incidence can be seen when effective screening is implemented.

Prevalence is the total number of cases of a disease present in a population at a specific time.

Increasing prevalence may indicate a climbing incidence, or indicate that the fatality rate of a disease has gone down.  Prevalence = new cases + old cases (still living and suffering).