Infant mortality and diminished entelechy in three European countries

Individual-level research reports that adverse environmental conditions during infancy increase the risk of mortality later in life. Extending this model to populations implies what we call the “diminished entelechy” hypothesis in which birth cohorts subjected to virulent environmental insults early in life experience increased mortality at older ages and do not realize their otherwise expected lifespan. Controversy remains as to whether the individual-level findings generalize to populations. We test the “diminished entelechy” hypothesis by measuring the association between infant mortality and life expectancy at age one for males and females born in Sweden (1751–1912), Denmark (1835–1913), and England and Wales (1841–1912). Time-series methods control for trends and other forms of autocorrelation that could confound the associations. Results support diminished entelechy in Sweden and England and Wales, but not in Denmark, in that environmental insults during infancy appear associated with reduced cohort lifespan. We then explored when in the life course the sequelae of infancy appear most salient. We examined cohort associations between infant mortality and mortality during childhood (1–4 years), youth (5–19 years), adulthood (20–54 years), and old-age (55–79 years). We generally find that infant cohort effects appear to “program” the mortality experience in youth, but not in adulthood or old-age. These findings conflict with the notion that improved conditions during infancy shaped the historical decline of old-age mortality.     

Gender-specific selection in utero among contemporary human birth cohorts

Much literature argues that natural selection has conserved mechanisms by which stressed females cull frail males in utero . This argument implies that males from low sex ratio birth cohorts should, on average, live longer than those from high sex ratio cohorts. Research reports such associations but these tests use completed lifespan as the outcome and, therefore, must end with cohorts born in 1913 because too many males survive from more contemporary cohorts to determine average lifespan. The empirical literature does not, therefore, address whether selection affects male mortality in contemporary cohorts. We apply time-series methods to monthly cohorts born in California between 1989 and 2003 to measure the association between the ratio of male to female live births and infant mortality, controlling for all forms of autocorrelation that induce spurious correlations.
Consistent with theories of selection in utero , we find a positive correlation between cohort sex ratio and male infant mortality. The results suggest that natural selection conserved the stress mechanism in females to end the gestation of relatively less fit males and that this mechanism manifests itself in contemporary human societies.     

What can lifespan variation reveal that life expectancy hides? Comparison of five high-income countries

ObjectivesIn most countries, life expectancy at birth (e0) has improved for many decades. Recently, however, progress has stalled in the UK and Canada, and reversed in the USA. Lifespan variation, a complementary measure of mortality, increased a few years before the reversal in the USA. To assess whether this measure offers additional meaningful insights, we examine what happened in four other high-income countries with differing life expectancy trends.DesignWe calculated life disparity (a specific measure of lifespan variation) in five countries -- USA, UK, France, Japan and Canada -- using sex- and age specific mortality rates from the Human Mortality Database from 1975 to 2017 for ages 0--100 years. We then examined trends in age-specific mortality to identify the age groups contributing to these changes.SettingUSA, UK, France, Japan and CanadaParticipantsaggregate population data of the above nations.Main Outcome MeasuresLife expectancy at birth, life disparity and age-specific mortality.ResultsThe stalls and falls in life expectancy, for both males and females, seen in the UK, USA and Canada coincided with rising life disparity. These changes may be driven by worsening mortality in middle-age (such as at age 40). France and Japan, in contrast, continue on previous trajectories.ConclusionsLife disparity is an additional summary measure of population health providing information beyond that signalled by life expectancy at birth alone.     

Analysis of sex,age and disease factors contributing to prolonged life expectancy at birth,in cases of malignant neoplasms in Japan

BACKGROUND: This study aimed to examine the contribution made by the change in mortality from malignant neoplasms to the life expectancy at birth, observed during the years 1965-1995 in Japan. METHODS: We used data on the population and number of deaths by cause, age and sex in 1965, 1975, 1985 and 1995. The contribution of different ages and causes of death to the change in life expectancy were examined with the method developed by Pollard. RESULTS: We found that, among all causes, the decrease of mortality from stomach cancer led to the greatest improvement in life expectancy for both sexes. On the other hand, negative contributions were seen with cancers of many sites, such as cancer of the intestine, liver and lung for males, and cancer of the intestine, gallbladder, lung and breast for females. Recently, the contributing years of all cancers have been negative because of the increase in mortality from malignant neoplasms. In addition, increase of death from malignant neoplasms in middle-aged and elderly people negatively influenced the life expectancy at birth. CONCLUSIONS: Female cancer influenced the improvement in life expectancy at birth. Cancer for males, however, contributed little to improvement of life expectancy at birth except for a little prolongation of life expectancy at birth during the years 1965-1975. To develop a public health policy, the contributing years to life expectancy at birth can be a useful indication in evaluating the impact of death from various diseases. It is necessary to analyze the contribution made by various causes of death to the changes of life expectancy at birth.     

Trends in dementia-free life expectancy among elderly members of a large health maintenance organization

BACKGROUND: This study examined the secular trends of life expectancy without dementia among elderly American members of a health maintenance organization, and observed if an increased life expectancy is accompanied by an increase in the duration of life with dementia. METHODS: The data derived from two chronological 9-year prospective cohort studies of members of the Kaiser Permanente Medical Care Program of Northern California. The first and second cohorts included 2,702 and 2,926 people aged > or =65 years free from dementia at baseline. Life expectancy without dementia or dementia-free life expectancy (DemFLE) is defined as the average number of years a person is expected to live without dementia. Total life expectancy is equal to the sum of DemFLE and life expectancy with dementia. Estimations of DemFLE were based on mortality data and incidence of dementia, using double-decrement life tables. RESULTS: Between the first and second cohorts, all-cause mortality rates declined, while the incidence of dementia remained constant in both men and women. Among the males, total life expectancy increased at a higher rate than DemFLE. Consequently, the duration of life with dementia was extended in the second cohort. Conversely, among the females DemFLE increased at a higher rate than total life expectancy, thus the duration of life with dementia decreased in the second cohort. The median age of dementia onset was postponed by 2-3 years in the second cohort for females, and did not show any specific difference between the two cohorts in males. CONCLUSION: The trends of health expectancies suggest an extension of the duration of life with dementia for males and a compression of dementia for females. A decreased incidence of risk factors for dementia among females in the second cohort such as stroke may explain these trends.     

Northern Territory indigenous life expectancy improvements, 1967-2004

OBJECTIVE: To assess the extent of changes in life expectancy at birth for the Indigenous population of the Northern Territory (NT) over the period 1967-2004, and to determine which age-specific mortality rates were mostly responsible for such change. METHODS: Life expectancy at birth figures were obtained via life table calculations using a high-quality and internally consistent dataset of NT Indigenous deaths and populations covering the period 1967-2004. A life expectancy at birth age decomposition technique was then applied. RESULTS: Indigenous life expectancy at birth has risen considerably in the NT, increasing from about 52 years for males and 54 years females in the late 1960s to about 60 years for males and 68 years for females in recent years. Significantly, for NT Indigenous females the gap with total Australian life expectancy has narrowed. CONCLUSIONS: In contrast to popular perception, Indigenous life expectancy in the Northern Territory has improved substantially from the late 1960s to the present. IMPLICATIONS: The widespread pessimism that surrounds Indigenous health and mortality is largely unfounded, at least for the NT. Although much remains to be done to reduce Indigenous mortality, the results in this paper demonstrate that improvements are occurring and that sustained and increased effort is worthwhile and will succeed.     

Changing mortality patterns in East and West Germany and Poland. II: short-term trends during transition and in the 1990s

OBJECTIVES: To examine trends in life expectancy at birth and age and cause specific patterns of mortality in the former German Democratic Republic (GDR) and Poland during political transition and throughout the 1990s in both parts of Germany and in Poland. METHODS: Decomposition of life expectancy by age and cause of death. Changes in life expectancy during transition by cause of death were examined using data for 1988/89 and 1990/91 for the former GDR and Poland; examination of life expectancy changes after transition were based on 1992-97 data for Germany and 1991-96 data for Poland. RESULTS: In both the former GDR and Poland male life expectancy at birth declined by almost one year during transition, mainly attributable to rising death rates from external causes and circulatory diseases. Female life expectancy in Poland deteriorated by 0.3 years, largely attributable to increasing circulatory mortality among the old, while in East German female rising death rates in children and young adults were nearly outbalanced by declining circulatory mortality among those over 70. Between 1991/92 and 1996/97, male life expectancy at birth increased by 2.4 years in the former GDR, 1.2 years in old Federal Republic, and 2.0 years in Poland (women: 2.3, 0.9, and 1.2 years). In East Germany and Poland, the overall improvement was largely attributable to falling mortality among men aged 40-64, while those over 65 contributed the largest proportion to life expectancy gains in women. The change in deaths among men aged 15-39 accounted for 0.4 of a year to life expectancy at birth in East Germany and Poland, attributable largely to greater decreases from external causes. Among those over 40, absolute contributions to changing life expectancy were greater in the former GDR than in the other two entities in both sexes, largely attributable to circulatory diseases. A persisting East-west life expectancy gap in Germany of 2.1 years in men in 1997 was largely attributable to external causes, diseases of the digestive system and circulatory diseases. Higher death rates from circulatory diseases among the elderly largely explain the female life expectancy gap of approximately one year. CONCLUSIONS: This study provides further insights into the health effects of political transition. Post-transition improvements in life expectancy and mortality have been much steeper in East Germany compared with Poland. Changes in dietary pattern and, in Germany, medical care may have been important factors in shaping post-transition mortality trends.     

Incidence rates of malignant mesothelioma in Denmark and predicted future number of cases among men

OBJECTIVES: This study analyzed the incidence rates of malignant mesothelioma in Denmark in order to predict the future number of cases that will occur among Danish men. METHODS: The 1912 cases of malignant mesothelioma reported to the Danish Cancer registry in 1943-1993 were analyzed in order to describe current incidence rates. By a Poisson regression model the relative risks of synthetic birth cohorts were estimated and used in the prediction of the future number of cases that will occur among Danish men. RESULTS: The incidence rate increased to 1.33 per 100000 person-years in 1983-1987 among men and to 0.51 in 1973-1977 among women. From the Poisson regression model, the risk for birth cohorts of men, relative to the 1940-1944 cohort, peaked in the 1940-1944 cohort and decreased to 0.57 in the 1950-1954 cohort. The age-specific incidence rate peaked at 246 per 100000 person-years in the age group 80-84 years. The future annual number of mesothelioma cases is expected to peak around 2015 with 93 cases among men born before 1955. CONCLUSIONS: The fit of the models was not ideal, but with careful interpretation of the results, it was concluded that a further increase in the number of mesothelioma cases can be expected, and the effect of regulating the environmental exposure to asbestos cannot be expected within the next 10-15 years.     

On Hendrikje van Andel-Schipper and other remarkable developments in the life expectancy of the Dutch population

The Netherlands was home to the oldest living individual in the world, Mrs. Hendrikje van Andel-Schipper, until she died at the age of 115 years on 30 August 2005. She illustrated the remarkable increase in centenarians in many European countries resulting from substantial increases in life expectancy at birth. In 2004, life expectancy at birth in the Netherlands reached a record high of 76.9 years for men and 81.4 years for women. These developments raise important questions on the potential for further increases in life expectancy. Based on an extrapolation of recent trends in cause-specific mortality, Netherlands Statistics predicts an increase in life expectancy of 2 to 3 years in the half-century between 2004 and 2050. Experts are deeply divided about the prospects for further increases in life expectancy. Some have argued that such estimates are too optimistic because, for example, the obesity epidemic might even reduce average life expectancy in the future. Others consider these estimates too pessimistic because, for example, previous estimates of limits to life expectancy have almost always been surpassed. Even relatively modest increases in life expectancy at birth, however, will pose important challenges to health care, social services and pension arrangements.     

Decomposition of life expectancy and expected life-years lost by disease

Life expectancy is commonly used to summarize the life-time mortality experience of a population. Differences in life expectancy are well-known across different levels of socioeconomic status such as income and education. A recent simulation study of potential life-years lost has shown the effects that major diseases contribute to differences in life expectancy at birth. We propose a general methodology to decompose life expectancy and expected life-years lost by disease in order to determine the contribution of diseases to differences in life expectancy at each given age. We show that the estimates for the life expectancy, expected life-years lost and their variances at each age can be computed backward recursively from an old age. The difference in life expectancy between groups will be shown to include contributions from diseases and life-year differences which occur after an old age cut-off beyond which the contribution of diseases cannot be easily determined. Diseases will be grouped into 14 major disease categories. Data from the National Longitudinal Mortality Study will be used for demonstration purposes.     

Women's death in Scandinavia — what makes Denmark different?

OBJECTIVE: To compare the mortality for women in Sweden, Norway and Denmark in order to search for clues for the low life expectancy of Danish women. METHODS: Prospective age-period-cohort study covering 40 years for all Swedish, Norwegian and Danish women aged 40-84 during the period 1960-2000, and born 1900-1950. OUTCOME MEASURES: Relative risks and 95% confidence intervals for deaths. RESULTS: The high risk of dying among Danish women was associated with being born between the two World Wars, and that a similar pattern was not found for women in Norway and Sweden. A tendency of a cohort effect was observed for Swedish women born around 1940. CONCLUSIONS: The currently low life expectancy of Danish women compared with that of women in Norway and Sweden is partly a transitional phenomenon caused by excessive death rates for women born between the two World Wars. Data on smoking prevalence by birth cohort and age indicate that a high percentage of Danish women in these cohorts were smokers throughout their adult life.     

Changing life expectancy in Romania after the transition

BACKGROUND: While Poland, Hungary, and the Czech Republic have seen impressive gains in life expectancy in the 1990s, Romania has not. In contrast with the other countries, there has been very little research on the causes of the pattern of mortality seen in Romania. OBJECTIVES: To describe the trends in life expectancy at birth in Romania after the political transition in 1989 and to evaluate the contribution of deaths from different causes and different ages to these changes. METHODS: Decomposition of life expectancy by age and cause of death using routine data on mortality for the years 1990, 1996, and 1998; comparison of death rates by age, sex, and cause of death. RESULTS: Romania has experienced an overall decline of 1.71 years of life expectancy at birth from 1990 to 1996 in men and 0.54 years in women. The major contribution to this decline was an increase in mortality from cardiovascular diseases and diseases of the digestive system, in particular cirrhosis, among the middle aged and elderly. The recovery observed in 1998, of 1.12 years in men and 0.89 years in women, was mainly caused by a reduction in deaths from cardiovascular disease in the middle aged and elderly. Infant and early childhood mortality fell throughout the period but there was an increase of approximately 40% in mortality at age 5-9 that was almost entirely attributable to AIDS. CONCLUSION: This is the first Romanian study that describes the evolution of life expectancy after transition. Romania may at last be beginning to follow the path of improving adult mortality seen in the early 1990s in some of its neighbours. It has, however, been unique in eastern Europe in experiencing increasing childhood mortality. This is attributable to an epidemic of paediatric AIDS, consequent on the tragically inappropriate policies adopted in the 1980s.     

Low-cost interventions accelerate epidemiological transition in Upper East Ghana

Before the 1950s effective medical interventions were not available and epidemiological transition in developing countries was mostly initiated by the introduction of mains water, sewage systems and personal hygiene. Nowadays, effective medical interventions such as vaccination programmes, medication and vitamin supplements might aid a swift transition. We recorded mortality among a research population of 18850 in Garu-Tempane district of Ghana from 2002 to 2005. We calculated the expected mortality based on the population structure in 2002 and compared the life expectancy of the region with other countries depending on their gross domestic product (GDP). Mortality in the age group 0-9 years was 8.1 per 1000 person-years and in the age group 10-19 years it was 4.1 per 1000 person-years. Cumulative survival probability up to age 20 years amounted to 89% and was far higher than expected. Observed and expected mortality in old age were similar. The life expectancy at birth was 59 years and much higher than the region's per capita annual income of US$100 would predict. We conclude that the population is in epidemiological transition. It shows that an epidemiological transition can be accelerated with low-cost interventions.     

Amenable mortality as a performance indicator of Italian health-care services

ABSTRACT: BACKGROUND: Mortality amenable to health-care services ('amenable mortality') has been defined as "premature deaths that should not occur in the presence of timely and effective health care" and as "conditions for which effective clinical interventions exist." We analyzed the regional variability in health-care services using amenable mortality as a performance indicator. Convergent validity was examined against other indicators, such as health expenditure, GDP per capita, life expectancy at birth, disability-free life expectancy at age 15, number of diagnostic and laboratory tests per 1,000 inhabitants, and the prevalence of cancer and cardiovascular diseases. METHODS: Amenable mortality rate was calculated as the average annual number of deaths in the population aged 0--74 years per 100,000 inhabitants, and it was then stratified by gender and region. Data were drawn from national mortality statistics for the period 2006--08. RESULTS: During the study period (2006--08), the age-standardized death rate (SDR) amenable to health-care services in Italy was 62.6 per 100,000 inhabitants: 66.0 per 100,000 for males and 59.1 per 100,000 for females. Significant regional variations ranged from 54.1 per 100,000 inhabitants in Alto Adige to 76.3 per 100,000 in Campania. Regional variability in SDR was examined separately for male and females. The variability proved to be statistically significant for both males and females (males: Q-test = 638.5, p < 0.001; females: Q-test = 700.1, p < 0.001). However, among men, we found a clear-cut divide in SDR values between Central and Southern Italy; among women, this divide was less pronounced. Amenable mortality was negatively correlated with life expectancy at birth for both genders (male: r = -0.64, p = 0.002; female: r = -0.88, p <0.001) and with disability-free life expectancy at age 15 (male: r = -0.70, p <0.001; female: r = -0.67, p <0.001). Amenable mortality displayed a statistically significant negative relationship with GDP per capita, the quantity of diagnostic and laboratory tests per 1,000 inhabitants, and the prevalence of cancer. CONCLUSIONS: Amenable mortality shows a wide variation across Italian regions and an inverse relationship with life expectancy and GDP per capita, as expected.     

Widening socioeconomic inequalities in US life expectancy, 1980-2000

BACKGROUND: This study examines changes in the extent of inequalities in life expectancy at birth and other ages in the United States between 1980 and 2000 by gender and socioeconomic deprivation levels. METHODS: A factor-based deprivation index consisting of 11 education, occupation, wealth, income distribution, unemployment, poverty, and housing quality indicators was used to define deprivation deciles, which were then linked to the US mortality data at the county-level. Life expectancy estimates were developed by age, gender, and deprivation levels for three 3 year time periods: 1980-82, 1989-91, and 1998-2000. Inequalities in life expectancy were measured by the absolute difference between the least-deprived group and each of the other deprivation deciles. Slope indices of inequality for each gender and time period were calculated by regressing life expectancy estimates on deprivation levels using weighted least squares models. RESULTS: Those in less-deprived groups experienced a longer life expectancy at each age than their counterparts in more-deprived groups. In 1980-82, the overall life expectancy at birth was 2.8 years longer for the least-deprived group than for the most-deprived group (75.8 vs 73.0 years). By 1998-2000, the absolute difference in life expectancy at birth had increased to 4.5 years (79.2 vs 74.7 years). The inequality indices also showed a substantial widening of the deprivation gradient in life expectancy during the study period for both males and females. CONCLUSIONS: Between 1980 and 2000, those in higher socioeconomic groups experienced larger gains in life expectancy than those in more-deprived groups, contributing to the widening gap.     

National health objectives for the year 2000: the demographic impact of health promotion and disease prevention.

BACKGROUND. The national objectives in Healthy People 2000, drafted by health professionals aware of currently available public health interventions, represent a wealth of information about near-term future mortality and morbidity. METHODS. Life table methods were used to calculate the impact of projected changes in mortality and activity limitation rates on life expectancy and expected disability years. RESULTS. Meeting the mortality objectives would increase life expectancy at birth by 1.5 to 2.1 years, raising life expectancy to 76.6 to 77.2 years. In addition, meeting the target for disability from chronic conditions would increase the number of years of life without activity limitations from 66.8 years to 69.3-69.7 years. If the targets for coronary heart disease and unintentional injury were changed to reflect recent trends, a greater improvement in life expectancy at birth would be achieved: from 1.8 to 2.7 years to 76.9 to 77.8 years. CONCLUSION. Meeting the targets would have an important demographic impact. Including changes in the coronary heart disease and injuries targets, life expectancy in the year 2000 would be above the middle of the ranges used in current Census Bureau projections.     

Placing Aboriginal and Torres Strait Islander mortality in an international context

OBJECTIVE: To assess whether the patterns of mortality observed among Indigenous Australians were seen in other countries or sub-populations. Previous reports have indicated that the life expectancy of Indigenous Australians compares unfavourably with that of Indigenous groups in other developed countries, and is similar to that in some developing countries. However, in contrast to many developing countries, low life expectancy of Indigenous Australians is the result of relatively high and early adult mortality, rather than high infant mortality. METHODS: Using routinely available administrative data on age-specific mortality and estimated life expectancy at birth, we compared data for Indigenous Australians (from the Northern Territory, Western Australia and South Australia combined) with corresponding data for 200 countries world-wide, as well as for several population groups of interest, including African Americans, Native Americans, Canadian Natives and New Zealand Maori. RESULTS: Patterns of mortality among Indigenous Australians were markedly different to those of most other populations with available data, with the exception of the Russian Republic. The age-specific mortality rates for Russian males in 1990-95 were almost identical to those of Indigenous males in 1995-97. The similarities among females were less pronounced, but stronger than for any other country. CONCLUSION AND IMPLICATIONS: The dramatic fall in Russian life expectancy has been studied extensively and several important social and contextual factors have been identified. These factors are also relevant for the Indigenous population, and this may help to explain the similar mortality patterns of the two groups.     

The standardized mortality ratio and life expectancy.

This paper develops a theoretical relation between the standardized mortality ratio (SMR) and the expected years of life and establishes a regression equation for easy conversion between these two statistics. The mathematical expression of the derived relation is an approximation, requiring an assumption of constant age-specific mortality ratios. It underestimates the "true" value calculated based on life table technique when the age-specific mortality ratios increase with age. This equation provides a conservative method to estimate the expected years of life for cohort mortality studies and facilitates an assessment of the impact of work-related factors on the length of life of the worker. It also allows one to convert the SMR to life expectancy in smaller studies whose sole objective is to determine the SMR in a working population. A 1% decrease (or increase) in the standardized mortality ratio will result in 0.1373 years increased (or decreased) life expectancy based on white male data for the US population. Furthermore, with data from 14 large oil refinery and chemical worker cohorts of white males, the "derived" expected years of life based on the regression equation closely predicts the corresponding value calculated using a standard life table technique. This statistical equation is expected to have practical applications when used in conjunction with the SMR to provide an approximate measure of life expectancy, a term and statistic familiar to most lay people.     

Changing life expectancy in the 1980s: why was Denmark different from Sweden?

OBJECTIVE: To identify the contribution from specific causes of death to the changes in life expectancy at birth in Denmark relative to Sweden in different age groups during the 1980s and to compare the difference in life expectancy between the two countries in 1990. DESIGN: Mortality data from WHO mortality tapes grouped in smaller series of clinically meaningful categories were used to calculate the contribution of each of these categories at each 10 year age group to the difference in life expectancy at birth in each country between 1979 and 1990 and between the two countries. SETTING: Denmark and Sweden. RESULTS: Between 1979 and 1990 life expectancy increased in both Denmark and Sweden. However, the increase in Sweden was more than two years while that in Denmark was less than one year. In both countries a decrease in cardiovascular disease mortality contributed most to the increase in life expectancy in males as well as females. In both sexes the smaller increase in life expectancy in Denmark was a result of differences in mortality trends in cardiovascular diseases and respiratory and non-respiratory cancers. CONCLUSION: Over a short time two Nordic countries experienced remarkable but different changes in mortality. These findings suggest that mortality rates are sensitive to even minor differences in social and cultural factors across countries and over short time periods.     

Geographical variation in life expectancy at birth in England and Wales is largely explained by deprivation

STUDY OBJECTIVE: To describe the population mortality profile of England and Wales by deprivation and in each government office region (GOR) during 1998, and to quantify the influence of geography and deprivation in determining life expectancy. DESIGN: Construction of life tables describing age specific mortality rates and life expectancy at birth from death registrations and estimated population counts. Life tables were created for (a) quintiles of income deprivation based on the income domain score of the index of multiple deprivation 2000, (b) each GOR and Wales, and (c) every combination of deprivation and geography. SETTING: England and Wales.PATIENTS/ PARTICIPANTS: Residents of England and Wales, 1998. MAIN RESULTS: Life expectancy at birth varies with deprivation quintile and is highest in the most affluent groups. The differences are mainly attributable to differences in mortality rates under 75 years of age. Regional life expectancies display a clear north-south gradient. Linear regression analysis shows that deprivation explains most of the geographical variation in life expectancy. CONCLUSIONS: Geographical patterns of life expectancy identified within these data for England and Wales in 1998 are mainly attributable to variations in deprivation status as defined by the IMD 2000 income domain score.