What Is Premature Death and Its Primary Causes?

Premature death refers to dying before reaching the age that most people in a given society can reasonably expect to live, and its primary causes are overwhelmingly chronic diseases, with heart disease and cancer at the top of the list in most countries. Researchers typically define it as death before age 70, though some studies use 65 or 75 as the cutoff. Globally, the share of people dying prematurely fell from about 56% in 1970 to 31% in 2019, but that progress has been deeply uneven across regions and demographics, and several disturbing trends are now pushing in the wrong direction.

How Researchers Measure Premature Death

The most common metric is the “proportion of premature deaths” (PPD), which captures what fraction of all deaths in a population occur before a threshold age, usually 70. The World Health Organization and most global health studies use this benchmark because it roughly corresponds to average life expectancy across developed nations. A related measure, “years of potential life lost” (YPLL), adds up the gap between each person’s age at death and the threshold, giving extra weight to deaths that happen very young. A 25-year-old dying in a car crash counts for far more YPLL than a 68-year-old dying of a heart attack, even though both are classified as premature.

Between 1970 and 2019, 34 countries managed to cut their PPD in half over a 30-year span, and among the 30 most populous nations, seven achieved that halving in roughly 50 years.¹ Child mortality drove much of that improvement; adult mortality has been slower to budge. But the global average masks stark gaps. In 2019, sub-Saharan Africa still had a PPD of 52%, while Western Europe and Canada were at roughly 15%.² One analysis framed this as sub-Saharan Africa being more than a century behind the frontier countries in premature mortality, with central Asia roughly 80 years behind and the United States about 38 years behind.³

Heart Disease and Stroke

Cardiovascular disease is the single largest contributor to premature death worldwide, and ischemic heart disease specifically has been the leading cause of premature cardiovascular mortality across all age groups from 1990 through 2019. In younger people (ages 15 to 19), stroke shares that top position with heart disease, but in every older bracket heart disease dominates.⁴ The risk factors are familiar: high blood pressure, high cholesterol, smoking, diabetes, obesity, and physical inactivity. What makes cardiovascular disease so lethal in terms of premature mortality is how early it can strike. A substantial share of heart attacks happen to people in their 40s and 50s, decades before what most would consider old age.

Chronic lung disease compounds the cardiovascular picture. Among people with type 2 diabetes, having COPD (chronic obstructive pulmonary disease) on top of diabetes tripled the rate of death from respiratory causes and increased overall mortality by about 23% compared to those without COPD.⁵ The clustering of chronic conditions in the same person, often driven by the same upstream behaviors, is one reason premature death rates are so hard to bring down once they take hold in a population.

The Rise of Early-Onset Cancer

Cancer is the second-largest cause of premature death globally, and an alarming trend has emerged over the past three decades: cancer in younger adults is becoming more common. Between 1990 and 2019, the global incidence of early-onset cancer (diagnosed before age 50) rose by about 79%, and early-onset cancer deaths climbed by roughly 28%. Breast, lung, stomach, and colorectal cancers carried the highest death toll and disability burden among younger patients.⁶ By 2021, there were an estimated 23.6 million new early-onset cancer cases and nearly a million deaths worldwide, with breast and lung cancers topping the list of killers.⁷

In the United States specifically, 14 cancer types showed rising incidence in at least one early-onset age group between 2010 and 2019. The biggest absolute jumps were in female breast cancer (about 4,800 additional cases above the expected number), colorectal cancer (about 2,100 extra cases), and kidney cancer (about 1,800 extra).⁸ Researchers point to dietary patterns, obesity, tobacco, and alcohol as key contributors, though the full explanation remains incomplete. The rise is too rapid to be genetic; something about how people are living is changing the risk landscape.

Wealth matters enormously here. Cancers that benefit from screening, like breast and colorectal cancer, show declining premature mortality in nearly all high-income countries but in a much smaller share of low-income ones. Cervical cancer, which benefits from vaccination programs rather than just screening, has declining premature mortality in about 90% of countries regardless of income level, suggesting that prevention programs can partly bypass the screening gap.⁹

Deaths of Despair and External Causes

Not all premature deaths are caused by disease. Injuries, suicide, drug overdose, and alcohol-related liver disease form a category sometimes called “deaths of despair,” a term that has become central to understanding premature mortality trends in several wealthy nations, the United States in particular. Between 1999 and 2015, the premature death rate among white Americans outside large urban areas rose significantly, driven largely by suicide, poisoning (mainly drug overdose), and liver disease. Researchers linked these trends to underlying social and economic upheaval in those communities.¹⁰

Feelings of despair among young adults are associated with higher odds of suicidal thoughts, illicit drug use, and opioid use.¹¹ The practical significance is that these deaths are concentrated in working-age people, meaning they carry an outsized impact on YPLL. A 30-year-old who dies of a fentanyl overdose loses 40 potential years, whereas a 68-year-old who dies of lung cancer loses two. This weighting is partly why the deaths-of-despair epidemic registers so heavily in premature mortality statistics even though the absolute number of deaths is smaller than the toll from heart disease or cancer.

Workplace hazards add another external dimension. Globally, hazardous working conditions cause a minimum of 312,000 fatal unintentional occupational injuries per year, translating to roughly 3.5 years of healthy life lost per 1,000 workers annually when both fatal and non-fatal injuries are counted.¹²

Air Pollution and Climate-Related Risks

Environmental exposure is an underappreciated driver of premature death, and fine particulate matter (PM2.5) from vehicle exhaust, industrial emissions, and wildfires is the single biggest environmental killer. Globally, roughly one million premature deaths per year between 2000 and 2019 were linked to short-term PM2.5 exposure alone, representing about 2% of all deaths worldwide.¹³ India bears a disproportionate share of this toll; annual premature mortality from ambient PM2.5 in India exceeds one million deaths.¹⁴ Even in a country like Australia, landscape fire-sourced air pollution was responsible for nearly 23,000 deaths between 2016 and 2019.¹⁵

Extreme heat is a growing contributor. Research shows that the risk of heat-related mortality has already increased substantially over the past two decades, and the extreme-heat years of the recent past are on track to become routine under continued warming. Limiting global temperature rise to 1.5°C rather than 2°C would significantly lower that risk, but for most locations, substantial adaptation will be needed regardless.¹⁶ Tropical and subtropical regions face the steepest projected increases in heatwave-related excess deaths, with countries like Colombia, the Philippines, and Brazil most affected.¹⁷

How Poverty and Inequality Shape Who Dies Young

Social and economic conditions are arguably the most powerful predictors of premature death, more powerful in many cases than any single disease category, because they determine who is exposed to the diseases and hazards in the first place. A nationally representative U.S. study found that low family income, lack of health insurance, unemployment, low education, and food insecurity collectively explained a large share of the gap in premature mortality between Black and white Americans. Family income below the poverty line and lack of private insurance were the two biggest contributors.¹⁸

England tells a remarkably similar story. An analysis of 2.5 million premature deaths found that roughly one in three was attributable to neighborhood deprivation, measured by factors like income, employment, education, and crime.¹⁹ Historical evidence from the United States shows that major policy shifts matter. The “War on Poverty” and civil rights legislation of the 1960s coincided with narrowing inequalities in premature death through 1980. After that, as antipoverty programs were rolled back and the minimum wage stagnated, the gap began widening again.²⁰

Mental Illness and Premature Mortality

People with mental health conditions die younger than the general population, and the gap is larger than most people realize. A systematic review and meta-analysis found that substance use disorders carried the shortest life expectancy, averaging about 57 years, with roughly 20 years of potential life lost. Eating disorders accounted for about 17 years lost, and schizophrenia-spectrum disorders around 15 years.²¹ Most of this excess mortality comes not from suicide, as people often assume, but from natural causes: the cardiovascular disease, diabetes, and respiratory illness that accumulate when mental illness makes it harder to manage health, access care, or maintain stable living conditions.

Data from a South African insurance cohort confirmed this pattern. Men with a mental health diagnosis lost nearly four years of life on average, and women about two years. Most of those lost years were attributable to natural causes, not suicide or accidents, though men with bipolar disorder or substance use disorders did lose a considerable number of years to unnatural causes as well.²² Tobacco is a major mediator. Among people receiving substance abuse treatment, over half of all deaths were tobacco-related, compared to about 31% in the general population.²³

Ultra-Processed Food as an Emerging Risk Factor

Diet has always been linked to premature death through its effects on heart disease, diabetes, and cancer, but a more specific culprit has gained attention: ultra-processed food. A large prospective study found that people eating the most ultra-processed food had about 62% higher risk of dying from any cause compared to those eating the least, with each additional daily serving raising mortality risk by roughly 18%.²⁴ A larger population-based cohort found a more modest but still meaningful 4% higher risk of total mortality for the highest consumers, with the association strongest for neurodegenerative deaths.²⁵

A cross-country analysis estimated that for every 10% increase in dietary share from ultra-processed foods, all-cause mortality rises by about 3%. In practice, this translated to an estimated 4% of premature deaths in Colombia and up to 14% in the United Kingdom and the United States being attributable to ultra-processed food intake.²⁶ The spread between those numbers reflects how deeply ultra-processed items have penetrated diets in the English-speaking world compared to countries with stronger traditional food cultures.

Biological Clocks and What They Reveal

At the molecular level, researchers now have tools to estimate how quickly someone’s body is aging, independent of their calendar age. Epigenetic clocks measure chemical tags on DNA that shift predictably with age, and when your epigenetic age runs ahead of your actual age, it signals higher mortality risk. Two of these clocks, known as GrimAge and PhenoAge, showed strong and consistent associations with death across large U.S. population studies.²⁷ Separately, shorter telomeres (the protective caps on chromosomes) also predicted higher mortality, and the two measures appear to capture somewhat independent biological processes.²⁸

These biological clocks are not just academic curiosities. In childhood cancer survivors, accelerated epigenetic aging was associated with worse cognitive function decades later, suggesting these markers can identify people at risk for early decline well before symptoms show up.²⁹ Similarly, genetic risk scores for coronary artery disease can independently predict sudden cardiac death. People in the highest genetic risk group had roughly 1.8 times the risk of sudden death compared to everyone else, even after accounting for heart function and clinical factors.³⁰ None of this is destiny; it is risk stratification that could, in theory, guide more aggressive prevention for the right people.

Why Men Die Younger

Across nearly every country and every era of modern record-keeping, men die younger than women. The gap persists even after controlling for occupational hazards and access to care, which points to a mix of biological and behavioral causes. On the biological side, hormonal differences, immune function, and genetic factors (including the fact that having two X chromosomes provides a backup copy of many genes) all play a role. On the behavioral side, men take more physical risks, are more likely to smoke and drink heavily, and are less likely to seek medical attention when symptoms appear.³¹ The productivity cost data reflect this disparity directly: across the European Union, men account for the majority of economic losses from premature death, ranging from about 65% in the Netherlands to over 80% in Poland.³²

The Economic Weight of Dying Young

Premature death is not just a health tragedy; it is an economic drain. Across the 28 EU member states in 2015, all-cause premature mortality generated production losses of roughly €175 billion, or about 1.2% of the bloc’s entire gross domestic product.³² Smoking alone drives a staggering share of these costs: productivity losses from smoking-related premature death accounted for over 75% of total lifetime costs in the United States and about 67% in Brazil.³³

These numbers create a strong economic argument for prevention. Modeling in the U.S. estimated that every 10% increase in treatment of high blood pressure would prevent roughly 14,000 deaths per year in people under 80, and a similar increase in cholesterol treatment or aspirin use would prevent about 8,000 deaths each. If all recommended clinical preventive services were used optimally, between 50,000 and 100,000 premature deaths could be averted annually in the United States alone.³⁴ Strong primary care systems are a foundation of that effort. Cross-country evidence consistently shows that robust primary care reduces illness and death, regardless of whether the benefit comes from having more primary care physicians, having a regular source of care, or receiving specific primary care features like continuity and coordination.³⁵

Neonatal Infection and Early-Life Vulnerability

While most discussion of premature death centers on adults, some of the youngest deaths are also among the most preventable. Neonatal infectious diseases remain a major cause of infant illness and death worldwide.³⁶ In low-resource settings, the combination of limited diagnostic tools, delayed antibiotic access, and fragile supply chains means infections that would be routine to treat in a well-equipped hospital become fatal. A child who dies in the first month of life loses an entire expected lifespan, making neonatal mortality one of the most YPLL-heavy categories of premature death. The progress made in reducing child mortality over the past half century has been real, but neonatal deaths have been slower to decline than deaths in older children, partly because the causes are more medically complex and harder to address with the public health interventions (like vaccines and oral rehydration) that drove gains elsewhere.