Key Takeaways

• In China, adequate access to healthcare at age 65, increased life expectancy by about 2 years, in contrast with those lacking access to healthcare. According to a study of the impact of the pandemic on Americans, over 338,500 lives could have been saved, if universal health care was accessible.
•  GDP per capita and population size are identified as the most significant factors responsible for variations in life expectancy across continents. Using income per capita and infant mortality rate as variables, a study found that improved population health and socioeconomic development reduced infant mortality rate, and consequently, increased life expectancy at birth.
• According to a study by the Finnish Institute for Health and Welfare, being under heavy stress can reduce life expectancy by 2.8 years. A Yale research proves that a stressful lifestyle can impact health at the DNA level, by making one's life “clock” tick faster.
• Health and longevity are influenced by subjective well-being. According to a study, high levels of subjective well-being is expected to add between 4 and 10 years to life. The result of research suggests that individuals with high levels of subjective well-being live healthier and longer lives than their counterparts.

Introduction

Access to Healthcare

•  Health inequity has always been a major problem, with disparities in access and results persisting among and in nations and regions and across gender, financial, and other demographic factors. Typically, without health insurance, access to a primary care doctor is limited, and waiting time at the hospital is longer. This increases the likelihood of suffering from preventable diseases and causes higher mortality rates.
• The United States stands out among rich countries as one where universal health insurance is not accessible to the population. Reduced life expectancy and growth in mortality rate have been attributed to this lack of universal access to healthcare. According to a study that measured the gravity of the impact of the COVID-19 pandemic on Americans, over 338,500 lives could have been saved if universal health care was accessible.
• In China, increased life expectancy among older adults was credited to adequate access to healthcare. Sufficient access to healthcare at age 65 increased life expectancy by about 2 years.
• According to Ann Keller (Associate Professor of Health Policy and Management at U.C. Berkeley), the occurrence of chronic diseases can be prevented with steady access to healthcare. Also, patients with such diseases can have them better managed.”

GDP per Capita

• Life expectancy varies across different continents. Several factors are responsible for this variation, with the most significant being GDP per capita and population size.
• An analysis of the relation between GDP and life expectancy using data from six countries suggests that the mortality rates are often elevated when the GDP of a country is high. Although the relationship is obvious, the impact size is modest. About 1% of adults are more likely to die in a year when the economic performance of a country is about five percent above average.
• Another study, however, reveals that by improving economic development in a country, GDP per capita increases the life expectancy at birth. Socioeconomic development such as economic conditions, the standard of living, health conditions, levels of poverty, and inequality, play an important role in the increase of life expectancy and longevity. The research which analyzed the correlation between socioeconomic development and life expectancy at birth, using income per capita and infant mortality rate as variables for the socioeconomic development in five countries, found that infant mortality rate reduced with improved population health and socioeconomic development; consequently, the life expectancy at birth seemed to increase.
• Generally, life expectancy in a country increases with national income, with some “punching above their weight”, while others “punch lower than their weight” — reaching a higher or lower lifespan than projected by their per capita income. A study of Brazil, Ethiopia, and the United States, identified sociopolitical and economic enhancements, and health care coverage as some possible drivers for extra 2 years of life expectancy in Brazil. While market-based healthcare and considerable rises in income inequality in the United States were some factors responsible for it punching 2.9 years below weight.

 

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Stress Levels

• Although there are no precise reasons for why people with neurotic personalities are more likely to have lower life expectancies, there is proof that neuroticism is associated with high cortisol levels — a hormone that is discharged when someone is stressed. High levels of cortisol have been proven to negatively impact the immune system and heart health. And a state of persistent stress can result in health conditions such as stomach ulcers, high blood pressure, and cardiovascular diseases.
• According to a study by the Finnish Institute for Health and Welfare, life expectancy is not only affected by conventional lifestyle-associated risk factors but also by factors linked to the quality of life, for instance, heavy stress. Life expectancy can be reduced by 2.8 years, in people who are under heavy stress.
• By tracking chemical changes in DNA, scientists can measure biological age — “epigenetic clocks” — which have proven to be better lifespan and health predictors than chronological age. According to Yale researchers, a stressful lifestyle can impact health at the DNA level, by making one's life “clock” tick faster.
• “Many people have had a gut feeling that stress makes us age faster, and our study proves that is true,” stated Zach Harvanek (Resident Psychiatrist and Yale researcher). The Yale study is the first tangible evidence that stress can negatively impact health beyond other physical or mental health conditions.

Self-Perceived Well Being

• Health and longevity are influenced by subjective well-being. Various studies have shown that a lesser subjective age is linked with better cognitive functions, mental and physical health, well-being, and happiness. Loosely described as satisfaction and gratitude for one's life, happiness, happens to be the psychological equivalent of vitamin C. Although not yet fully understood, a positive attitude to life protects against the negative effects of stress and becoming sick. A study of older adults discovered that physical function was better maintained in happier people than those who were unhappy; even walking speeds dropped more slowly.
• Another study connecting happiness to longevity involving a group of nuns, revealed that of the most optimistic quarter of nuns, 90% were alive at age 85, but just 34% of the least cheerful quarter were. The happiest nuns lived 10 years more. According to a Compendium of Factsheets by the Department of Health, high levels of subjective well-being can add between 4 and 10 years to life.
• The length of a perceived healthy life can be estimated using self-rated health as a marker. Studies have revealed that self-perceived health is associated with several health outcomes including morbidity onset, physiological dysregulation, and mortality. An analysis of 9761 participants suggests that individuals with high levels of subjective well-being live healthier and longer lives than their counterparts.

 

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Research Strategy

Key Takeaways

•  The First Public Health Revolution happened between 1880 and 1920. This period witnessed significant advancements in healthcare and disease prevention. These advancements resulted in a significant increase in life expectancy.
•  Vaccines and antibiotics had a significant impact on life expectancy. Diseases such as smallpox and polio had claimed millions of lives before this intervention.
• Waterborne diseases affect morbidity and mortality. Microbes that cause diseases such as cholera and typhoid could not be filtered out with traditional methods of filtration. Water purification and supply impacted the life expectancy rate significantly.

Introduction

Global Life Expectancy Overview

• Life is vastly different from what it was about 200 years ago. In the 1800s, the average lifespan was 35 years, which is attributed to poor sanitation, crowded housing, limited knowledge of nutrition, and poor sewage management, among others. Diseases such as "tuberculosis, pleurisy, typhus, tonsillitis, cholera, and dysentery" resulted in death during infancy or childhood. 

• The richest countries in the world have a life expectancy rate higher than 80 years. Japan has the highest life rate at 85 years while the Central Africa Republic registers the lowest count at 53 years. According to the CDC, the US life expectancy rate in 2020 was 77 years. Although there was a gentle growth in the 1800s, the increase in life expectancy was accelerated drastically in the 1900s.

 

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• Over the past 200 years, the life expectancy in the US has more than doubled. The chart below demonstrates how life expectancy has grown over the years, with a side-to-side comparison of developed countries, developing countries, and the global average.

 

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#1. Improvement in Public Health and Medicine

• Over the past 200 years, improvement in public health has been one of the leading factors that have contributed to the improvement of the global life expectancy rate. The greatest improvement in the data is demonstrated between 1880 and 1920. This period, referred to as the “First Public Health Revolution”, saw a great increase in control of infectious diseases, improved access to cleaner water, safer food, and overall social improvement. By addressing these issues, this period eliminated several causes of death that plagued the world.

• Vaccines are one of the key advancements in healthcare and medicine to date. They have had a significant impact on life expectancy by drastically reducing mortality rates. Diseases such as smallpox and polio had killed millions of people across the globe. The chart below demonstrates how various infectious diseases were addressed by the use of vaccines and medication. As the chart demonstrates, although some vaccines were introduced in the 1800s, they were more widely used in the 1900s.

 

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•  Antibiotics introduced in the 1940s to address bacterial infections increased the average lifespan by about 5-10 years globally. The Antibiotic Era (1935-1960) saw the largest widespread implementation of medical intervention. Scholars have noted that sulfa drugs had a significant impact on the decline of the mortality rate. Although not all scholars agree, some state that the introduction of penicillin had a significant impact as well. Over the years, new technological advancements such as CT scans have allowed the treatment of certain diseases before the onset of symptoms, preventing complications. Today, telemedicine has increased access to medical treatment and insights.
• In the 1800s, the US GDP percentage of medical spending was low and so was life expectancy. The chart below demonstrates the amount of money spent against the year. As is demonstrated, there has been a significant increase in the 1900s, which is also reflected in the increase in life expectancy.

 

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• The leading causes of death in the past 100 years have also shifted. Diseases that were considered incurable now have vaccines and medication. The table below provides a side-by-side comparison of the primary causes of death in 1900, 1950, and 2000. The critical public health concerns in the US have also shifted.

 

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#2. Improved Hygiene and Living Conditions

• Over the past 200 years, improvements in hygiene and living conditions have had an impact on global life expectancy. These efforts include implementing modern plumbing and sewer systems. This has significantly mitigated contact with bacteria that would lead to illness, hence improving life expectancy. Although medical intervention addresses diseases, improvements in hygiene and living conditions also had a significant impact by preventing diseases such as cholera and dysentery.
• Inventions in this space have played a great role in improving hygiene and living conditions. Toilets invented in 1875 saved one billion lives, synthetic fertilizers developed in 1909 saved one billion lives, water chlorination saved 175 million lives, and pesticides invented in 1945 saved 25 million lives.
• Access to clean water affects morbidity and mortality. Alongside several other factors, water purification and supply have been a point of concern within every community. Although ancient communities may have been able to purify water, these efforts were not effective in addressing the microbes that cause diseases such as typhoid. The chart below provides data for Philadelphia, providing a small scope analysis of the impact of treated water within a community/region.

 

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•  Disinfection has also played a critical role in the availability of clean drinking water. In the US, New Jersey was the first city to implement this in 1908. Many more cities across the US implemented this within the next decade dramatically reducing the morbidity rate. By the mid-1900s, the incidence of typhoid and cholera decreased drastically. The chart below demonstrates this change before the widespread implementation of vaccines.

 

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Additional Insights

• Studies have shown that mortality is decreased by 30%-35% in people that regularly exercise. One's lifestyle has an impact on health and vulnerability to diseases such as hypertension, coronary heart disease, and diabetes. Additionally, one's nutrition plays a great role. A diet that prioritizes fruits, vegetables, whole grains, and lean meats improves one's longevity.
• Regions dubbed the Blue Zones demonstrate longer lifespans of about 100 years. Blue Zones are the regions in the world where life expectancy is the highest thanks to their lifestyle and diet choices, which suggests the importance of these factors. These regions include "Okinawa, Japan; Sardinia, Italy; Nicoya, Costa Rica; Ikaria, Greece, and even stateside in Loma Linda, California."
• As technological advancements evolve, human beings will continue to unravel more insights into how the body works. By doing so, we could continue to witness an increase in life expectancy. The past 200 years have witnessed a sky-rocket increase as significant strides are taken in general health improvements and the prevention of diseases. The table below demonstrates how life expectancy in the US has changed based on gender and race.

 

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Research Strategy