Life Expectancy Measurements

David M.J. Naimark , in International Encyclopedia of Public Health (Second Edition), 2017

Conclusion

Life expectancy can be understood to be equal to the area under a survival curve regardless of its shape. A gain in life expectancy associated with adopting one health strategy over another (or of being in one exposure group vs another) is the area between the respective survival curves. In order to put a given gain into proper perspective, it is necessary to understand the baseline risk in the control group and the proportion of people who are likely to benefit from the intervention. It is certainly a misconception to view gains in life expectancy as increments of time tacked onto the end of a fixed life span. Life expectancy can be estimated from empirical data by a variety of methods that each have strengths and weaknesses.

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Longevity of Specific Populations

Thomas Theodore Samaras , in International Encyclopedia of Public Health (Second Edition), 2017

Worldwide Variations in Life Expectancy

Life expectancy is the median age at death for a particular population group. For example, if a group of people have a life expectancy at birth of 70  years, half died before 70 and half survived beyond this age. Note that life expectancies are also determined for each age group, usually in 10-year increments.

Life expectancies are available for over 200 populations ranging from China to the tiny sovereign states of Andorra and San Marino. As shown in Table 1, life expectancy at birth for males and females combined range from 33.22   years for Swaziland to 83.51   years for Andorra (Wikipedia, 2006).

Consistent with findings that a good environment and SES promote longevity, most of the longest living populations are found in highly developed populations with superior sanitation, education, and health care. The worst life expectancies are found in Africa with its lower economic development and very high rate of mortality from HIV/AIDS infection. The top 10 populations in terms of descending life expectancy (83.51–80.42   years) are Andorra, Macau, San Marino, Singapore, Hong Kong, Japan, Sweden, Switzerland, Australia, and Guernsey (UK). (Depending on the year, the ranking varies somewhat, but has essentially remained unchanged over the last 15   years).

The low life expectancy of developing versus developed populations does not mean that elderly people are absent from developing populations. Since poor countries tend to have much higher infant death rates, this situation lowers the average life expectancy. In addition, early deaths of children and young adults due to malnutrition and infections reduce the average life expectancy. However, if early death is avoided, adults often reach advanced ages (Walker, 1974; Samaras, 2007, 2013).

A common misconception in comparing today's life expectancy to that of earlier times, such as the 1900s, is the belief that individuals can expect to live 25–30   years longer. However, if we look at the life expectancy of elderly people, the picture is quite different; e.g., 60-year-old white males could expect to live 6.6   years longer in 2004 versus 1900, and 80-year-olds could live 3   years longer. This is a small increase in view of the exceptional health and medical developments over the last century. Our workweek has also declined from about 60 to 40   h per week with increased worker safety and benefits.

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AMERICAS, SOUTH | Early Villages

Robert A. Benfer , in Encyclopedia of Archaeology, 2008

Palaeodemography

We estimated life expectancy from the distribution of the dead by age groups, using plausible levels of population growth rates. Fewer infant burials in #200 argue for greater investment in children, who, as discussed above, showed less stunting of growth. The lack of scars of pregnancy in the public and ilium bones of women younger than 24  years suggests that marriage was delayed, reducing fertility. High levels of cadmium in human bone samples likely reduced male fertility, perhaps most strongly in #200. Adult life expectancy increased over time at Paloma only to decrease in subsequent time periods at other sites. In Ecuador, Ubelaker also found a decline following the Preceramic period. A recent compilation of studies by Mark Cohen shows a similar decline in health and life expectancy of adults is associated with initial experiments with intensive agriculture in prehistoric peoples widely scattered around the earth.

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United Kingdom, Health System of

Rebecca Surender , ... Pavel Ovseiko , in International Encyclopedia of Public Health (Second Edition), 2017

Conclusion

As life expectancy increases and the population ages, the NHS will face greater demand on its scarce resources than ever before in its history. The health conditions the NHS was created to combat are not the primary health conditions that challenge British society today: Chronic diseases like diabetes and heart disease have supplanted infectious diseases as the major causes of death. This changing pattern of disease will require health policy makers to think of health system design in a different way, to break through the historical divide between 'medicine' and 'public health,' and to focus on promoting health rather than responding to illness. Moreover, increasingly, at the beginning of the twenty-first century, important decisions are being faced about how many of the constantly appearing scientific products of medical science can be provided by public funds. More than at any stage of its history, the value and effectiveness of services in the NHS are being scrutinized. Nevertheless, because access to a wide range of modern health-care facilities has been provided by means of public funding of the NHS for so long, the NHS continues to remain a strikingly popular institution in public opinion, despite its many upheavals.

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The Crust

A.C. Kerr , in Treatise on Geochemistry (Second Edition), 2014

4.18.3 Preservation of Oceanic Plateaus

The life expectancy of oceanic crust, from formation at a mid-ocean ridge to recycling into the asthenosphere at a subduction zone, is of the order of 150–200  Ma. Consequently, the oldest in situ oceanic plate is the Jurassic crust of the western Pacific (Pringle, 1992). However, since oceanic plateaus are much more buoyant than oceanic crust of 'normal' thickness formed at a mid-ocean ridge, they have a greater potential to resist subduction and, instead of being completely recycled back into the mantle, the upper layers can be 'peeled off' (Kimura and Ludden, 1995) and accreted on to island arcs and active continental margins (e.g., Ben-Avraham et al., 1981; Cloos, 1993; Kimura and Ludden, 1995). The net result is that oceanic plateaus are more likely to be preserved in the geological record than normal oceanic crust.

Older plateaus are colder and so less buoyant than younger plateaus and, as a result, a plateau that collides with a subduction zone shortly after its formation (<   5Ma) is less likely to be subducted than an older plateau (Cloos, 1993). For example, the Pacific-derived Caribbean plateau collided with the Cretaceous 'Great arc' of the Caribbean <10   Ma after the plateau formed at ~90   Ma (Burke, 1988; Hastie and Kerr, 2010; Hastie et al., 2008; Kerr et al., 2003; Thompson et al., 2004b). As a result, a significant proportion of the more buoyant plateau accreted to the arc. Similarly, the Ontong Java Plateau collided with the Solomon Islands arc at ~100   Ma, following its formation at ~120   Ma (e.g., Mann and Taira, 2004; Petterson et al., 1997). Again, the plateau has largely resisted subduction (Wessel and Kroenke, 2000) because of (1) the thick crust (Abbott and Mooney, 1995; Cloos, 1993), (2) relatively little in the way of postemplacement subsidence ( Section 4.18.4.5.1 ), and (3) a >   300-km thick, rheologically strong, and chemically depleted mantle 'root' (Klosko et al., 2001; Richardson et al., 2000).

When an oceanic plateau clogs a subduction zone, a range of events can happen depending on the plate tectonic setting ( Figure 4(a) ). (1) At an island arc, the subduction direction can reverse (subduction 'flip' or polarity reversal), for example, the collision of the Ontong Java Plateau with the Solomon Islands subduction zone. (2) As well as subduction flip, plateau collision with an oceanic arc can also result in subduction initiation behind the plateau ( Figure 4(a) ). For example, a subduction zone initiated at the trailing edge of the Caribbean plateau at 75–90   Ma to form the still-active Central American arc (Burke, 1988; Kerr et al., 2003; Figure 5 ). (3) Plateau collision with a continental arc results in the formation of a new subduction zone behind the accreted plateau, but with no associated subduction flip ( Figure 4(b) ). This occurred in the Late Cretaceous, when the more southerly part of the Caribbean plateau collided with, and accreted to, the northwestern edge of South America (Kerr and Tarney, 2005; Kerr et al., 2003; Figure 5 ).

Figure 4. Idealized cross-sections illustrating the likely effects of the collision of an oceanic plateau with (a) an island arc and (b) an active continental margin.

 Modified from Kerr AC and Mahoney JJ (2007) Oceanic plateaus: Problematic plumes, potential paradigms. Chemical Geology 241: 332–353.

Figure 5. Map showing the main accreted outcrops of the Caribbean–Colombian oceanic plateau along with the locations of DSDP/ODP drill holes that penetrated the thickened crust of the Caribbean plate.

Although many of the in situ Cretaceous oceanic plateaus have been drilled by the Deep Sea Drilling, Ocean Drilling, and Integrated Ocean Drilling programs, the insight that these drill holes can provide is limited compared to the accreted oceanic plateau sections. For instance, subduction polarity reversal along with plateau accretion and the formation of a new subduction zone have resulted in the uplift and exposure of much deeper sections than could ever be sampled by drilling of both the Ontong Java Plateau on the Solomon Islands (Neal et al., 1997; Petterson et al., 1999) and the Caribbean plateau around its margins and along the coast of northwestern South America ( Figure 5 ). It is in ways such as these that remnants of these thick, buoyant oceanic plateaus can be preserved and incorporated into the continental crust, thus making them more accessible for detailed study ( Figure 4 ).

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South Asia, Health Systems of

Brian Chin , ... Sekhar Bonu , in International Encyclopedia of Public Health (Second Edition), 2017

Health Status of the Population

The average life expectancy at birth in South Asia is 67  years and ranges from 60   years in Afghanistan to 77   years in Maldives (Table 2), lower than the average of 75   years in East Asia. Between 1960 and 2012, under-5 mortality rates per 1000 live births declined from 266 to 60 in the region, although the gains are not uniform across countries (Figure 1). A recent Global Burden of Disease Study estimated an annualized rate of decline in under-5 mortality of 3.9% (compared to 7.9% in East Asia) between 2000 and 2013 for South Asia ranging from 1.8% in Pakistan to 6.7% in Maldives (Kassebaum et al., 2014). Afghanistan continues to have highest child mortality in the region, though declined child mortality has accelerated in recent years.

Table 2. Health status in South Asia

Indicators Afghanistan Bangladesh Bhutan India Maldives Nepal Pakistan Sri Lanka
Life expectancy at birth (years) 60 70 68 66 77 68 65 75
Life expectancy at birth, males (years) 58 69 68 64 76 67 64 71
Life expectancy at birth, female (years) 61 71 69 68 78 69 66 78
Healthy life expectancy (HALE) at birth, males (years) 49 60 58 56 66 58 56 63
Healthy life expectancy (HALE) at birth, females (years) 49 61 59 58 67 60 57 68
Probability of dying (per 1000 population) between 15 and 60   years (adult mortality rate), males 294 159 221 242 91 197 190 186
Maternal mortality ratio (per 100   000 live births) 400 170 120 190 31 190 170 29
Annualized rate of % decline in under-5 mortality rate (2000–13)∗ 3.6 5.6 4.9 4.3 6.7 6.1 1.8 4.8

Source: Global Health Observatory of the World Health Organization (2012) and; Global Burden of Disease Study 2013∗.

Figure 1. Trends in under-5 mortality rate in South Asian countries, 1960–2012.

 From http://www.childinfo.org/mortality_ufmrcountrydata.php.

Although maternal mortality has been estimated to have declined from 550 per 100   000 births in 1990 to 190 in 2013, the ratio is still unacceptably high and is 11 times higher than that in the high-income countries (17). The lifetime risk of dying during pregnancy for a woman in South Asia is 1 in 190, compared to 1 in 13   600 in Sweden. However, the regional average hides considerable inter-country variations in maternal mortality ratio that range from as low as 29 in Sri Lanka to 190 in India and Nepal and to 400 in Afghanistan (Table 2). The lifetime risk of dying during pregnancy in Afghanistan is 1 in 49 – among the highest in the world. South Asia has the unfortunate distinction of having the lowest proportion of births attended by skilled health-care personnel, increasing from only 30% in the 1990s to 50% in 2012.

Widespread undernutrition among women, including high rates of iron deficiency anemia (52% of pregnant women in South Asia are anemic – highest prevalence among all regions), is of particular concern, especially among poor women. South Asia has the highest prevalence of child malnutrition (38% stunted, 32% underweight, and 58% anemic) in the world. Rampant iron and other micronutrient deficiencies, combined with overall undernutrition, especially among the poor, is not only keeping children at an educational learning disadvantage from an early age: it is also leading to intergenerational transmission of poverty and other disabilities.

Infections such as tuberculosis (TB) continue to be one of the leading causes of death among young adults. South Asia has the second highest incidence rate of tuberculosis (187 per 100   000 population) second only to the Africa region and has 3 (Afghanistan, Bangladesh, and India) of the 10 countries with the highest burden of TB. India carried the world's greatest burden of TB cases (26% of total cases worldwide) in 2012. Afghanistan is estimated to have the highest prevalence and mortality rate of 358 cases and 37 deaths, respectively, per 100   000 population. Though the incidence rate of TB is declining in South Asia by about 2% annually (compared to 6.5% in Europe) since 2000, there is threat of reversal of gains made with emergence of multidrug resistance TB (MDR-TB). India has one of the largest increases in MDR-TB patients that were eligible for treatment in 2011–12. In addition, a significant proportion of the regional population continues to live in malaria-prone areas with significant morbidity and mortality with the second highest incidence and mortality rates after sub-Saharan Africa, though significant gains have been made in malaria control also in the recent years.

Approximately 1.7–2.9   million people are estimated to be living with HIV/AIDS in South Asia; 90% living in India. India and Nepal has the highest estimated prevalence (0.4% among adults) in the region, yet both countries have successfully reduced the number of new infections by more than 50%. However, the epidemic continues to expand in some countries (e.g., Bangladesh and Sri Lanka) (UNAIDS, 2013). Although the rate in the population at large is still low (0.4%), in absolute numbers due to its large population, India has the third largest HIV-positive populations in the world after South Africa and Nigeria. Other countries in the region have a low prevalence among the general population (<0.1%), but have significantly higher rates among subpopulations that are engaging in high-risk behaviors, such as injecting drugs with contaminated needles and high-risk sex behavior.

Substantial gains have been made in control of communicable diseases though these still contribute to the maximum years of life lost in all the countries in the region, except in Sri Lanka. The brunt of communicable diseases is mainly borne by children, women, and marginalized sections of the population. Though the agenda for control of traditional infectious diseases such as malaria, tuberculosis, and HIV/AIDS still remains unfinished, the region is being confronted with new emerging infectious diseases such as dengue, chikungunya, influenza, etc., which may escalate with climate change and increasing globalization. Overall, almost 39% of the disability-adjusted life years (DALYs) lost in the region is accounted for by communicable, maternal, perinatal, and nutritional conditions. Infectious and parasitic diseases contribute to 15% of the DALYs lost, followed by neonatal (13%) and respiratory infections (6%).

While the challenge of communicable diseases continues, the burden of non-communicable diseases has dramatically increased (49% of the DALYs lost), followed by injuries (12% of the DALYs lost) (Table 3). Other than Afghanistan and Pakistan, all the other countries are experiencing an epidemiological transition from communicable to non-communicable diseases. Many of the non-communicable diseases affect young and middle-aged populations, which adversely affects workforce productivity. Cardiovascular diseases, diabetes mellitus, and chronic obstructive pulmonary diseases have already reached epidemic proportions in India. Moreover, the burden of injuries is increasing in the region, especially those due to road accidents in the working-age population.

Table 3. Disease and disability burden of population in South Asia

Indicators Afghanistan Bangladesh Bhutan India Maldives Nepal Pakistan Sri Lanka
Age-standardized mortality rate for non-communicable diseases (per 100   000 population) 1117 702 735 685 598 620 711 623
Age-standardized mortality rate for cardiovascular diseases (per 100   000 population) 634 421 366 328 229 279 361 214
Age-standardized mortality rate for cancer (per 100   000 population) 131 183 171 108 59 178 152 130
Age-standardized mortality rate for injuries (per 100   000 population) 149 91 105 99 53 58 92 233
DALYs lost to communicable diseases (%) 51 37 30 37 19 38 48 14
DALYs lost to non-communicable diseases (%) 33 52 50 51 73 50 40 71
DALYs lost to injuries (%) 16 10 20 12 9 11 11 15

Source: Global Health Observatory of the World Health Organization (2008 and 2012).

However, with better uptake of preventive services (e.g., immunization, clean water and sanitation, better nutrition, maternal services, etc.), the communicable diseases are relatively more concentrated among the poor, while the non-communicable diseases are rising across all the socioeconomic groups, contrary to the commonly held view that non-communicable diseases are diseases of the rich. A number of risk factors including tobacco and alcohol consumption are much higher in the poorest population in South Asia. This is leading to a double burden of communicable and non-communicable diseases among the poor, which has the potential to accentuate the inequities in health outcomes. Though the consumption of ʻmanufacturedʼ cigarettes – a major form of tobacco consumption in developed countries – is relatively low in South Asia (only 3–4% of world consumption compared to South Asia's 23% share of the global population), tobacco consumption is highly prevalent in South Asia and takes many other forms and as hand-rolled cigarettes (bidis), chewing tobacco inside a betal leaf, etc. Prevalence of smoking of any tobacco product among men, 15 years and older varies from 26% in India to 46% in Bangladesh (World Health Organization, 2012).

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Volume 1

Françoise G. Bourrouilh-Le Jan , in Encyclopedia of Environmental Health (Second Edition), 2019

Life Expectancy and Tax Haven (or Fiscal Paradise)

But, the life expectancy in the Bahama Archipelago was 72.3 years in 2007 and 74.7 years in 2013, with a fertility rate of 2.27 children per woman and an urban population of near 90%. This figure might indicate a fragile population in comparison to the natural food resources, as only sugarcane and pineapple are cultivated, with few market garden produce, on 1% of the cultivated land. The other areas cannot be cultivated due to the absence of soil and the presence of a modern-day, visible developing karstic surface.

There is an apparent contradiction between the high life expectancy (74.7 years) in the Bahamas and seemingly poor economy. This is only apparent; the history of the archipelago shows that the country is a tax haven, or a fiscal paradise, since Sir Harry Oakes' arrival in 1934—in other words, for 75 years, representing nearly three human generations (one generation is counted as 30 years), during which money flew easily inside and through Bahamian banks and population. As for tourism, it started around 1870, nearly 150 years ago, and brings now in the archipelago 3,400,000 around 1990–2000 and 5.8–5.9 million visitors in 2012, against 369,670 inhabitants, a rate of 1 inhabitant for 20 tourists. If a basic tourist spends at least $ 2000 in the islands (travel, hotel, restaurants, souvenirs, and presents), it represents a total amount of 120.108 dollars per year, thus 30,000 $ for each inhabitant per year (including babies and retired persons). In consequence, the two factors, tourism and tax haven, have significantly improved the inhabitant life quality, despite a poor economy, creating numerous positions in the third sector (hotels, banks, offices, etc.); these politics have lasted at least for three generations and brought emulation for population education, but it remains a fragile economy as it is linked to the world exchange and world tourism.

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Cancer and Senescence

Koji Itahana , Goberdhan P. Dimri , in International Encyclopedia of Public Health (Second Edition), 2017

Abstract

The dramatic increase in life expectancy around the globe has resulted in a significant increase in chronic health problems such as cardiovascular diseases and cancer, which are often associated with aging. The exact role of the aging process in the development of these chronic diseases is under intense investigation in numerous laboratories. Recent studies suggest that the aging process at the cellular level, which is also known as cellular senescence, at least partially contributes to these chronic health problems. Here we discuss the age-related increase in cancer incidence and the possible role of cellular senescence in cancer development. We also discuss the therapeutic potential of cellular senescence in cancer treatment.

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Volume 3

R. Benigni , A. Giuliani , in Encyclopedia of Environmental Health (Second Edition), 2011

Gender Differences in Life Expectancy

It is of interest to compare the gender differences in cancer incidence with the parallel gender differences in life expectancy.

The normalized sex difference in life expectancy at birth (ΔLIFE) for the various countries is calculated in a way similar to that adopted for ΔN:

Δ LIFE = female life expectancy − male life expectancy male life expectancy

Positive values of ΔLIFE describe female advantage, and vice versa. Figure 6 presents the values, with the countries clustered by geographic area.

Figure 6. The distribution of ΔLIFE values. The 'global area' effect is lower than for ΔN. Here the world regions are more internally heterogeneous, in terms of the general social conditions. The within-area variation is of the same order of magnitude of the between-area variation.

An analysis of variance demonstrates the statistical significance of the geographic distribution of ΔLIFE values (F=13.07; p<.0001), pointing that significant differences exist between different areas.

As for cancer incidence, the majority of countries are characterized by male disadvantage (positive ΔLIFE), with the exception of a few developing countries (Niger, Burkina Faso, Kenya, Afghanistan, Nepal, and Paraguay). In fact, Africa, the Middle East, and South Asia form a large belt of countries characterized by either low male disadvantage or female disadvantage. The male disadvantage increases in the order: East Asia<South America<Western countries<Eastern Europe<former Soviet Union. During their recent political transition, many Eastern European and former Soviet Union countries have undergone a very rapid and dramatic decrease in life expectancy, especially for the male population. This phenomenon has attracted the attention of many investigators, and the concomitant action of material deprivation, stress, and stress-related behaviors (e.g., increased alcohol consumption) has been hypothesized.

The general lesson that can be derived from the analysis of ΔLIFE distribution is that the differences among countries change gradually and consistently according to the differences in social, economical, and cultural characterization (as approximated by the geographic classification). With respect to cancer incidence, the female advantage in life expectancy seems to be almost invariant across different countries and cultures. However, at present, there is not enough evidence to decide whether or if this is a 'biologically rooted' feature (over which the environment simply plays a modulating role); the existing explanations (going from anthropological to evolutionary ones) are still largely incomplete and unsatisfactory. What can be surely said is that ΔLIFE appears as a much more 'biologically determined' parameter than ΔN; this is to be expected, given that cancer – only in relatively recent times (and in affluent geographic areas) – became a demographically relevant cause of death. On the contrary, on ΔLIFE impinges the entire biological history of humans.

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Volume 3

C. Stein , in Encyclopedia of Environmental Health (Second Edition), 2019

Trends in Life Expectancy

Over the past 50 years, average life expectancy at birth increased globally by nearly 20  years; this equates to an average increase in life expectancy of approximately 4   months per year (Fig. 1).

Fig. 1

Fig. 1. Trends in life expectancy at birth in developed and developing countries.

 From World Health Organization. (2003). The world health report 2003 – shaping the future. Geneva: WHO. https://www.who.int/whr/2003/en/ (accessed 29 October 2018).

As shown in Fig. 1, the gap between developed and developing countries was only closed by those developing countries whose life expectancy had already been higher from the outset while those with the highest mortality in the 1950s had only modest gains. Therefore, the large life expectancy gap between developed and developing countries observed in the 1950s has changed to a wider gap within developing countries at the beginning of the 21st century.

Over 60% of deaths in the developed world occur in people older than 70   years, compared with 30% in developing countries. Hence, the vast majority of deaths in developing countries occur in young adulthood and childhood (Fig. 2).

Fig. 2

Fig. 2. Age distribution of global mortality in developed and developing countries in 2002 (number in thousands). Note: The term developed countries includes Australia, Canada, European countries, former Soviet countries, Japan, New Zealand, and the United States. High-mortality developing countries include those Sub-Saharan Africa, and countries with high child and adult mortality in Asia, Central and South America, and the Eastern Mediterranean. Other developing countries are referred to as "developing–low mortality."

 From World Health Organization. (2003). The world health report 2003 – shaping the future. Geneva: WHO. https://www.who.int/whr/2003/en/ (accessed 29 October 2018).

Developing countries, however, are not uniform in their age distribution of mortality (Fig. 2). This is particularly evident when comparing a low-mortality developing country such as China (where nearly 17% of the world's population live) with high-mortality developing countries in Africa (with 10% of the global population). Less than 10% of all deaths in China are in children under 5   years of age compared with 40% in Africa.

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