Topic outline

  • 204 LIFE STAGE MORTALITY

    To go back to the previous Course, click the title here 203 Human Reproduction.

    • 204.1 Stages of Life related to Mortality & Cause of Death

      To lighten up this otherwise morbid topic, let's first hear from Integrative Biologist Joao Pedro de Magalhaes as he explains what aging is and how we can extend our lifespan (with the help of PhD Comics).
         
      Well that was interesting - maybe science will come up with some breakthrough to extend human lifetime to infinity - but not yet!  So let's proceed with our study of mortality rates over a finite human lifespan.
      Age Specific Mortality Rates vary through a wide range of ages and by sex.  Just after birth and into early childhood, mortality rates are generally very low.  At older ages from the end of working life onwards, mortality rates become a significant percentage and climb very steeply.  Female mortality rates are lower than Males at all ages except in the very old centenarian ages. You can see this illustrated by the graph of Age Specific Mortality Rates for Australia for males and females from the Australian Government Actuary's Life Table - ALT 2010-12 (click link below).
      We will examine mortality in age range life stages in this Course 204. This will allow you to see how cause of death varies by life stage. You will also be able to see the age range where historical improvements have occurred. Causes of Death can be analysed in a life stage structure.  Click on the link below to see a Table of Causes of Death for Australia (males and females combined) by age group over the years 2012 to 2014.
      Notice how similar types of cause are colour coded and change over life stages. 
      Deaths in the first year of age are referred to as Infant Mortality and they have declined substantially over time in most countries that developed high quality health care and high living standards.  To give you an indication of how this developed in Australia, the following link shows you that at 1900, deaths of Male children age 0 to 4 represented about 25% of all Male deaths whereas by 2000, they represented only 2% of deaths.
      In the Adolescent/Young Adult range of 15 to 24, risky behaviour and struggles with maturity and mental health are a feature of 2012 to 2014 cause of deaths.  Survival after working life ends (65+) is of interest for determining retirement pension costs. Dementia, often associated with old age (and aged care costs), begins to become prominent from age 75.
      This leads to the following life stage structure we have established for examining mortality rates in this course:
      In the next 6 topics we will discuss the mortality rate characteristics of these 6 life stage categories shown above. In this discussion we will (for brevity) quote   mortality rates for all persons (male and female combined). More discussion on separate Male and Female life expectancy differences will be found in the next Course 205.



      • 204.2 Stage 1 - Infant Mortality Rate (0-1)

        The first year of life has traditionally been an established special case studied in Demography. It has a specific rate defined called the Infant Mortality Rate (IMR). It is the number of deaths per 1,000 live births of children under the age of 1 year.
        In times when plagues and diseases were more prevalent, babies were very much at risk in the first few years year of life. In countries with less developed health services and unhealthy water supplies and sewerage, rates of death of infants are quite high for some countries but big improvements have been made by the efforts of the 1990 UN Millennium Development Goals and national income growth of many formerly developing countries.  This is neatly explained by the following 2 minute video from the late Hans Rosling. (Note that this video quotes child mortality rates (age 0 to 4) rather than infant mortality rates (first 12 months).
           
        Whilst Infant Mortality Rates are very low in countries like Australia, there is still a strong community focus on reducing the risk of infant death towards zero if at all possible.  From 1971 to 2011 the Australian Infant Mortality Rate has reduced from 17.3 per 1000 to 3.8 per 1000 (a reduction of 78%).
        Here is the analysis by the Australian Institute of Health and Welfare of the leading causes of death for the first year of life in 2012-14 (note SIDS means "sudden infant death syndrome").
        The following links to a table of 239 countries sorted in order of 2016 Infant Mortality Rate. Australia ranks 24th.
        • 204.3 Stage 2 - Childhood (1 -14)

          This stage and the remaining 4 stages are not traditional ones used in studying mortality rates. It will become apparent when we move to study total life span and life expectancy, how these discrete stages have contributed to longer lifetimes.
          From 1971 to 2011, the average of mortality rates in this age range has reduced from 0.60 deaths per 1000 to 0.13 per 1000, a reduction of 77%.
          Here is the AIHW analysis of leading causes of death covering this age group in 2012-14.
          • 204.4 Stage 3 - Adolescence/Young Adult (15 - 24)

            This is the category where human development of a maturity of brain and lifestyle risks are major risk factors. In this life stage risk factors are adventurous pursuits, indulgence in alcohol and illicit drugs, careless motor vehicle driving and mental illness.
            In the early days of young people able to own their own car and with no testing of blood alcohol levels, the mortality curve was known as including a road accident hump. This has been reduced with blood alcohol testing and speeding restrictions and penalties. This is illustrated in the following link to graphs of Australian motor vehicle accident deaths (drivers and passengers) from 1900 to 2000. You will see the surge in this for the age 15 to 24 group from 1950 to 1980 and steep decline since then.
            Unfortunately this recent improvement has been moderated by the emergence of higher rates of suicides with this being the most frequent cause of death in this age group in 2012-14.  Below is the AIHW analysis of leading causes of death for this age group.
            Overall, from 1971 to 2011, the average of mortality rates in this age range has reduced from 1.71 deaths per 1000 to 0.53 per 1000, a reduction of 69%. 


            • 204.5 Stage 4 - Mature Adult (25-64)

              This life stage is the engine room of society - where careers are built, life partnerships formed, assets accumulated, life goals pursued and community leadership roles taken on. Changes in Mortality Rates in Australia over this life stage have been characterised by shift of occupations from dangerous manufacturing industries to technology and service industries. The reduction in smoking has also led to significant reduction in mortality rates in the mid to later ages of this stage.  
              From 1971 and 2011 the average of mortality rates across this age range reduced from 8.56 deaths per 1000 to 2.89 per 1000, a reduction of 66%.
              Below is the analysis of leading causes of death for this age group in 2012-14.

              • 204.6 Third Age (65-74)

                This stage is the early years of retirement an provides opportunity for self-direction and autonomy and personal fulfilment not possible during fulltime work. It is also the age when grandchildren emerge and time is spent assisting their care and development. The "Third Age" is a term which has become associated with this period as used in the "University of the Third Age".
                However while these are all positive aspects of lifestyle in this stage, mortality risks starts to rise associated with circulatory diseases and cancer as was seen in the Cause of Death table in 204.1. The average rate of mortality in this age range was 16.83 deaths per 1000 in 2011 which is almost six times the average rate of death in Stage 4 age 25 to 64 age group.
                Below is the analysis by AIHW for leading causes of death for this age group in 2012-14 (note COPD means "chronic obstructive pulmonary disease").