Inequalities in Life Expectancy and Cardiometabolic Disease Mortality Across and Within High-Income Countries

Summary:

Cardiometabolic disease is a leading cause of death and plays a key role in recent life expectancy trends worldwide. We highlight inequalities in cardiometabolic disease mortality across sex, race/ethnicity, geographic region, and urbanicity within the United States, as well as across high-income countries.

Differences in longevity and metabolic disease mortality across high-income countries

Today, high-income countries have achieved among the highest life expectancy levels observed in human history. Life expectancy at birth for Japanese women, the world leaders, reached a remarkable 87.44 years in 2019.¹ However, there are striking life expectancy differences even among these long-lived populations (Figure 1A–1B). Newborn girls in Japan and newborn boys in Switzerland, the best performers in this set of 21 high-income countries, can expect to live much longer than their counterparts residing in countries like the United States, the United Kingdom, Portugal, Germany, and Denmark. In 2019, the life expectancy gaps between the US and the best performers reached 5.43 and 5.96 years for men and women, respectively. The size of these gaps is substantial. Considering that a very robust rate of life expectancy increase is 2.5 years per decade for countries that have reached fairly high life expectancy levels,² these gaps mean that poorly performing countries like the US have fallen decades behind their peers.

Figure 1. Life expectancy and cardiometabolic disease mortality across high-income countries.

Life expectancy at birth and age-standardized cardiometabolic disease mortality in men (A and C) and women (B and D) in 21 high-income countries. Most recent year available in 2016–2019. Data sources: Human Mortality Database and World Health Organization Mortality Database

Chronic diseases including circulatory diseases, respiratory diseases, and metabolic diseases are among the primary contributors to these life expectancy gaps.³ Risk factors such as high blood pressure, impaired glucose regulation, dyslipidemia, obesity, sedentary lifestyle, and smoking contribute to several forms of both cardiovascular diseases and metabolic diseases; this cluster of conditions is often referred to jointly as cardiometabolic diseases.⁴ Among this set of countries, metabolic, nutritional, and endocrine diseases (referred to hereafter as “metabolic diseases”, ICD-10 codes E00-E88) accounted for 1.4% to 5.1% of total deaths among this set of countries in 2019, while cardiovascular diseases related to metabolic risk factors (referred to hereafter as “cardiovascular diseases”, ICD-10 codes I00-I69) accounted for 19.3% to 40.3% of total deaths.⁵ Death rates from both metabolic and cardiovascular diseases tend to be higher among men than among women.

There are significant differences in cardiometabolic disease mortality across these high-income countries (Figure 1C–1D). The US, Austria, and Germany have the highest death rates, while Japan, France, the Netherlands (men), and the UK (women) have the lowest death rates. These cross-national differences are considerable, with American men experiencing cardiometabolic disease death rates that are nearly twice as high as Japanese men (294.44 per 100,000 versus 151.28 per 100,000), and Austrian women experiencing death rates nearly two and a half times those of Japanese women (218.10 per 100,000 versus 91.02 per 100,000). Considering the metabolic component alone, Japan, Finland, and the UK have the lowest metabolic disease death rates, while the US, Austria, and Portugal have the highest metabolic disease death rates. This is the case for both men and women. Metabolic disease mortality in the countries with the highest death rates is 2.8 to over 3.3 times higher on average than in the countries with the lowest death rates. The patterns are slightly different for the cardiovascular component alone. Japan, France, Australia (men), and Denmark (women) have the lowest cardiovascular disease mortality rates, while Austria, Germany, the US (men), and Greece (women) have the highest rates. For cardiovascular disease, the death rates are 1.7 to 2 times higher on average in the countries with the highest death rates compared to countries with the lowest death rates.

One question we might ask is whether countries with higher cardiometabolic disease mortality tend to have lower life expectancy. These quantities do appear to be weakly correlated. For example, countries like the US, Germany, and Portugal tend to have both relatively low life expectancy and higher cardiometabolic disease mortality, and countries like Japan, France, and Spain tend to have relatively high life expectancy and lower cardiometabolic disease mortality. However, there are also countries with relatively low life expectancy (e.g., the UK and Denmark) that do not experience particularly high levels of cardiometabolic disease mortality. Factors that may play a role in driving these patterns includes differences in countries’ smoking epidemics over the past century, obesity rates, alcohol consumption, diet, physical activity patterns, and orientations towards the prevention and treatment of metabolic risk factors like hypertension, high cholesterol, high blood glucose, and diabetes.

In addition to cardiometabolic diseases, other leading drivers of the US life expectancy shortfall include external causes like drug- and alcohol-related deaths, motor vehicle accidents, and gun deaths.^3,6 These causes of death predominate at the prime adult ages—ages 25 to 64—indicating that young and middle-aged Americans are dying from largely preventable causes of death. Their counterparts living in better-performing peer countries experience substantially lower mortality risks at these ages. Striking similarities exist across these causes of death: they are much more strongly influenced by broader social and structural factors rather than a lack of access to health care. For example, the US and other Anglophone countries experienced substantial increases in drug overdose mortality over the past two decades. These epidemics were initially catalyzed by the widespread prescribing of opioids driven by high patient volumes, financial incentives to provide quick fixes, and a high degree of pharmaceutical influence in the health care system. Death rates from car accidents are particularly high in the US due to extensive commuting, lack of investment in public transit, and slower progress in implementing road safety innovations. The US has been a longstanding outlier in terms of access to firearms, which is exacerbated by conditions including concentrated poverty and residential segregation. A substantially higher proportion of homicides are caused by guns in the US than in its peer countries, and the recent uptick in homicide rates in the US is concerning against a backdrop of long-run declines in homicide.

Differences in longevity and metabolic disease mortality within the United States

In addition to cross-national variation in both longevity and cardiometabolic disease mortality, stark differences in these outcomes are often observed across population subgroups within high-income countries. This section describes overall trends as well as disparities in metabolic disease mortality within the United States. Over the past two decades, metabolic disease mortality has displayed a U-shaped pattern: death rates began decreasing in the early 2000s but have been on the rise since 2010 (Figure 2A–2B). For women, metabolic disease mortality in 2019 still remained below its 1999 level, but for men, metabolic disease mortality in 2019 reached its highest level over this twenty year period. Metabolic disease death rates were roughly 50% higher among American men than American women in 2019. The trends for cardiovascular disease mortality differ, with both men and women experiencing sustained decreases since 1999 (although progress reducing cardiovascular disease mortality was considerably greater prior to 2013 than in subsequent years). In 2019, American men experienced cardiovascular disease death rates that were about one and a half times those of women.

Figure 2. Inequalities in cardiometabolic disease mortality within the United States.

Cardiometabolic disease mortality between 1999 and 2019 and in 2019 by race/ethnicity, geographic region, and urbanicity in men (A, C, E, and G) and women (B, D, F, and H) in the United States. All estimates are age standardized. Data source: National Center for Health Statistics

Racial/ethnic disparities in life expectancy are longstanding in the US. In 2019, among five major racial/ethnic groups – Hispanics, Non-Hispanic American Indians or Alaska Natives (AIAN), Non-Hispanic Asians (Asians), Non-Hispanic Blacks (blacks), and Non-Hispanic Whites (whites) – Asians had the highest life expectancy at birth (87.4 years for women, 83.5 years for men), followed by Hispanics (84.4 years for women, 79.1 years for men) and whites (81.3 years for women, 76.3 years for men).⁷ AIAN populations had the lowest life expectancy levels at 75.0 years for women and 68.6 years for men, followed by blacks, whose life expectancies were 78.1 years for women and 71.3 years for men.⁷ Among these groups, blacks had the highest cardiometabolic disease death rates in 2019, followed by whites and AIANs (Figure 2C–2D). Hispanics and Asians had the lowest cardiometabolic disease death rates, experiencing rates that were 40–60% (men) or 30–40% (women) lower than blacks. Considering the metabolic disease mortality component alone, blacks had the highest death rates followed by AIANs and Hispanics. Ranking by the cardiovascular disease mortality components follows the same pattern as total cardiometabolic disease mortality.

Prior research has also highlighted large and growing geographic disparities in longevity along both regional and urban/rural dimensions within the United States.^8–10 Since 1990, mortality has decreased more rapidly in coastal and metropolitan areas than in interior and nonmetropolitan areas, leading to a striking divergence in life expectancy. Among ten regions in the US, the East South Central (Alabama, Kentucky, Mississippi, and Tennessee), Appalachian, and West South Central (Arkansas, Louisiana, Oklahoma, and Texas) regions had the highest cardiometabolic disease death rates in 2019 (Figure 2E–2F). These are also the regions that have tended to experience particularly adverse overall mortality trends over the past few decades. The Pacific and New England regions, which are doing the best, had cardiometabolic disease mortality rates that were 19–30% lower than in the three worst-performing regions. Considering metabolic disease mortality alone, the patterns would be fairly similar, but the Mountain region would do worse while the Middle Atlantic region would improve. We see a clear metropolitan-nonmetropolitan gradient in cardiometabolic disease mortality, with nonmetropolitan areas experiencing the highest cardiometabolic disease death rates followed by medium/small metros, large central metros, and large fringe metros. This pattern also holds for the metabolic and cardiovascular disease mortality components. Men and women living in nonmetropolitan areas in 2019 experienced metabolic disease death rates that were 39% and 49% higher, respectively, than their counterparts living in large fringe metros. Differences across geographic region and levels of urbanicity within the US may be related to the differential distribution of health behaviors like smoking¹¹ and other cardiometabolic risk factors, as well as to differences in health care access, quality, and infrastructure.

Future Outlook

Populations around the world are undergoing epidemiological and nutrition transitions, which are driving increasing prevalences of cardiometabolic risk factors like obesity, hypertension, impaired glucose regulation, and dyslipidemia. These metabolic risk factors are in turn important contributors to many leading causes of death worldwide. For decades, high-income countries have been at the forefront of these trends, which emerged more recently in low- and middle-income countries. The contemporary and historical experiences of high-income countries may be instructive for low- and middle-income countries now experiencing a rising burden of cardiometabolic risk factors, disease, and mortality.

Since 2010, several high-income countries have experienced a notable stagnation in life expectancy gains, with the US experiencing among the most adverse trends.⁶ Slowdowns in reductions in cardiovascular disease mortality are a key contributor to the stalled progress in life expectancy¹², and it is likely that metabolic risk factors and disease may be contributing to this phenomenon. In some countries, rises in drug overdose mortality have also impeded improvements in life expectancy. The rising levels of drug and alcohol use observed in some countries may have important implications for the development of cardiometabolic disease, but this remains understudied. Over the longer run, high-income countries have generally achieved reductions in hypertension and improvements in cholesterol levels, but increases in the prevalence of obesity, poor glucose regulation, and diabetes.¹³ It is important to note that there is heterogeneity across countries in the prevalence of metabolic risk factors, the relationships between various risk factors and the development of metabolic disease, and the prevalence of metabolic disease. For example, levels of obesity are relatively low in countries like Japan and Switzerland, which still incur burdens of metabolic disease. In the coming decades, it is likely that the greatest burden of metabolic disease will fall on low- and middle-income countries. It is concerning that the health care systems in many of these countries are poorly equipped to detect, monitor, and treat metabolic risk factors and conditions.

We are also likely to continue observing important inequalities in metabolic disease mortality within countries. Factors hypothesized to contribute to these disparities include differences between groups in socioeconomic status, behavioral factors like smoking and alcohol consumption, and access to health care.¹¹ While some trends, like reductions in cigarette smoking, may be favorable, it is alarming that countries like the US have witnessed increases in metabolic syndrome across racial/ethnic groups and at younger ages.¹⁴ Cardiometabolic risk factors may also have elevated the severity of and mortality from COVID-19¹⁵, particularly among vulnerable populations. It is likely that we will continue to experience periodic global pandemics in the coming decades. During these pandemics, specific population subgroups with high burdens of cardiometabolic disease may face higher risks of morbidity and mortality.