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The Systems Ageing Index - Dr Mark Burgin

10/06/19. Dr. Mark Burgin BM BCh (oxon) MRCGP uses a theory of ageing based upon the function of physiological systems to create a novel multidimensional index.

Chronological age in healthy adults has a strong correlation with disability and life expectancy and its predictions can be improved by considering life-style changes.

Age calculators find it more difficult to describe the biological age of the individual when they develop illness and for this reason, I have created a different approach.

The theory that ageing is due to failure of the body’s various systems would be superior as a description of biological reserve than any measures of disability. (1)

Conflating disability and ageing is logically inconsistent as a child with a disability may have a normal life expectancy and old people may suffer from minimal disability.

The systems ageing index is based upon a simplistic model that problems with each system are independent from each other and they are additive.

This scoring system was chosen for its simplicity and need to make comparisons between different patterns of ageing to give a flexible structure for collecting data and research.

To those who note that there is no mention of endocrine dysfunction, I say that this is deliberate, because these functions can largely be replaced by medication they are not now fatal.

Against the criticism that lifestyle can lead to immediate death from drug or alcohol overdose or fall from a high place I would accept the argument but counter that ageing is not part of the mechanism.

Ten biological systems

The choice of the systems was based around the observations that anatomical structures and physiological functions are linked and those chosen are necessary for life.

  • The heart provides circulation of blood and can be assessed by normality at rest and under stress from exercise and assigned a qualitive value.

  • The lungs provide gas exchange which can be assessed using spirometry and gas exchange can be directly measured so a quantitative value can be estimated.

  • The kidneys provide fluid balance and clearing of some toxins and can be assessed with high degree of accuracy with estimated glomerular filtration rate.

  • The liver metabolises toxins and the blood tests only indicate the damage to the liver cells but not residual function, imaging can only indicate a range of values.

  • Skin protects the body from fluid loss, infection and trauma and can examined easily to estimate the extent of changes and give a quantative value.

  • Bowels and their associated secretions break down food and absorb nutrients and assessing their function is challenging although weight gives a global estimate.

  • Muscles and skeleton provide the body with support and movement and assessment of function is straightforward as there are many measures of mobility.

  • The blood provides cells for fighting infection and other injuries and there are many measures to assess the function and frequency of infection gives an alternate way of measuring.

  • The peripheral (and autonomic) nervous system takes sensory information and through reflexes produces motor and endocrine effects so defects in the functions are usually obvious.

  • The cerebrum takes patterns of information and processes it to create thoughts and defects such as language, recognition of objects and memory can be measured.


Each of the ten biological systems are scored from 1 (minimal function) to 10 (full function) using the best estimate of how the system is performing.

The total score (out of 100) provides an overview of the person’s residual youth from a nominal 100% so death will occur from organ failure at some value.

It can be expected that some patients will die with a score of 90 and others with score of 10 but most will be at a value between.

As a lawyer it can be a useful and simple tool to check whether life expectancy calculations are sensible and to give perspective in complex disability cases.

This value is expected to be lower in countries with good health and social care systems and less in those without but the opposite is also possible.

If a person is exposed to infections then many systems might deteriorate in a younger person who can compensate better than an older person who is protected by immunisation.

The purpose of the scoring is therefore to provide a baseline so that the figures can be analysed and compared to determine the real contribution of systems failure to health and ageing.

Until methods for obtaining precise figures are available and research provides a normal range it is possible to self-score with estimates for amusement as I have illustrated below.

Doctor Mark Burgin, BM BCh (oxon) MRCGP is on the General Practitioner Specialist Register.

Dr. Burgin can be contacted on This email address is being protected from spambots. You need JavaScript enabled to view it. and 0845 331 3304 website

  1. Gonçalves J, Gomes MI, Fonseca M, Teodoro T, Barros PP and Botelho M-A (2017) Selfie Aging Index: An Index for the Self-assessment of Healthy and Active Aging. Front. Med. 4:236. doi: 10.3389/fmed.2017.00236



Score (ten is best)











Toxin breakdown




















Total function remaining % = 76%

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