Wealth and longevity: double inequality
Canadian researchers from the University of Toronto, working under the leadership of Ryan Hum, used the Michaelis-Menten equation to analyze the mortality of adults and children in regions with different levels of per capita income. This well-known mathematical model, one of the developers of which was Maud Menten, who received her Doctor of Medicine degree from the University of Toronto in 1911, was first used in 1913 to analyze the kinetics of enzymatic activity.
The authors justified their choice by the fact that, just as chemical catalysts affect the rate of the enzymatic reaction, income-related factors affect the average life expectancy.
According to the results obtained using the Michaelis-Menten model, compared with 1970, the average life expectancy of people around the world continues to increase, which is generally accompanied by a decrease in the "cost" of additional years of life. However, the dynamics of this indicator depends on the level of per capita income. Thus, for adult men in low-income countries, the cost of an additional year of life is increasing, while the cost of an additional year of life for children and adult men in high-income countries continues to decline.
The authors explain this by the fact that over the past decades, the main areas of research and development of new technologies (drugs, vaccines and strategies) have been the health of children and the fight against infectious diseases. At the same time, investments in the development of methods for the treatment of chronic diseases of adults remained at a relatively low level.
Developing an analogy between catalysts and income, the researchers reasoned as follows: income directly provides the opportunity to introduce certain technologies, immunization programs, epidemiological education, as well as sanitary and hygienic and other measures that can be considered as "catalysts" - agents that increase the rate of reaction and are only partially consumed in the course of its course.
They formulated the definition of a new parameter, "critical income" – the level of income required to achieve half of the maximum absolute life expectancy observed in rich countries. For example, in 1970, this figure was 1.48 US dollars per day. By 2007, it had dropped to $1.21 per day. In other words, compared to the conditions of 40 years ago, today a lower national income is required to achieve a longer life expectancy.
However, this good news is mainly due to the improvement of children's health and an increase in life expectancy in high-income countries. For adults (aged 15-59 years) in low-income countries, the critical income has increased since 1970, on the contrary. This pattern applies more to adult men; for women, this trend is less pronounced.
The authors note that an increase in the number of smokers, especially among adult men, as well as the prevalence of HIV infection has a significant impact on life expectancy. On the contrary, the attention paid everywhere to children's health, including the active development of new technologies and vaccines, as well as political attitudes, means a more "rosy" future for children, that is, a reduction in the cost of a chance for a longer life.
Article by Ryan J Hum et al. Global divergence in critical income for adult and childhood survival: analyses of mortality using Michaelis-Menten is published in the journal eLife.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the University of Toronto:
Global Longevity Not Fairly Distributed, say U of T Researchers.
18.12.2012