Causes Of Mortality Decline Research Articles

The Reversal of Fortunes: Trends in County Mortality and Cross-County Mortality Disparities in the United States

BackgroundCounties are the smallest unit for which mortality data are routinely available, allowing consistent and comparable long-term analysis of trends in health disparities. Average life expectancy has steadily increased in the United States but there is limited information on long-term mortality trends in the US counties This study aimed to investigate trends in county mortality and cross-county mortality disparities, including the contributions of specific diseases to county level mortality trends.Methods and FindingsWe used mortality statistics (from the National Center for Health Statistics [NCHS]) and population (from the US Census) to estimate sex-specific life expectancy for US counties for every year between 1961 and 1999. Data for analyses in subsequent years were not provided to us by the NCHS. We calculated different metrics of cross-county mortality disparity, and also grouped counties on the basis of whether their mortality changed favorably or unfavorably relative to the national average. We estimated the probability of death from specific diseases for counties with above- or below-average mortality performance. We simulated the effect of cross-county migration on each county's life expectancy using a time-based simulation model. Between 1961 and 1999, the standard deviation (SD) of life expectancy across US counties was at its lowest in 1983, at 1.9 and 1.4 y for men and women, respectively. Cross-county life expectancy SD increased to 2.3 and 1.7 y in 1999. Between 1961 and 1983 no counties had a statistically significant increase in mortality; the major cause of mortality decline for both sexes was reduction in cardiovascular mortality. From 1983 to 1999, life expectancy declined significantly in 11 counties for men (by 1.3 y) and in 180 counties for women (by 1.3 y); another 48 (men) and 783 (women) counties had nonsignificant life expectancy decline. Life expectancy decline in both sexes was caused by increased mortality from lung cancer, chronic obstructive pulmonary disease (COPD), diabetes, and a range of other noncommunicable diseases, which were no longer compensated for by the decline in cardiovascular mortality. Higher HIV/AIDS and homicide deaths also contributed substantially to life expectancy decline for men, but not for women. Alternative specifications of the effects of migration showed that the rise in cross-county life expectancy SD was unlikely to be caused by migration.ConclusionsThere was a steady increase in mortality inequality across the US counties between 1983 and 1999, resulting from stagnation or increase in mortality among the worst-off segment of the population. Female mortality increased in a large number of counties, primarily because of chronic diseases related to smoking, overweight and obesity, and high blood pressure.

The Relative Importance of the Causes of Mortality Decline: A Review Essay

This essay looks at and critiques analyses of the causes of mortality decline by three scholars namely: P.E Razzell (1974) with his paper An Interpretation of the Modern Rise of Population in Europe-A Critique.; Thomas McKeown (1976) with his book The Modern Rise of Population; and Abdel Omran (1977) with his article Epidemiologic Transition: Theory. Razzell believes inoculation against smallpox was the main cause of mortality decline while McKeown believes that the virulence of the organisms diminished and the improvements in the environment are what led to the decline. Both of them base their arguments on data from eighteenth and nineteenth century England and Wales. Omran, on the other hand, theorizes about the three main stages of the epidemiologic transition. The essay looks at their arguments and counterarguments and critiques them.

M R Smallman-Raynor and A D Cliff, War epidemics: an historical geography of infectious diseases in military conflict and civil strife, 1850–2000, Oxford University Press, 2004, pp. xxxv, 805, illus., £100 (hardback 0-19-823364-7).

M R Smallman-Raynor and A D Cliff, War epidemics: an historical geography of infectious diseases in military conflict and civil strife, 1850–2000, Oxford University Press, 2004, pp. xxxv, 805, illus., £100 (hardback 0-19-823364-7).

Commentary: Mortality decline in Senegal

Sub-Saharan Africa has become associated in the minds of many with news stories about famine, civil war, or hospitals overwhelmed by terminally ill AIDS patients. The continent’s success stories receive less news attention. Delaunay et al. present results from a study documenting the reductions in infant and child mortality achieved in rural Senegal since the 1960s. 1 In the Niakhar area, the probability of a child dying in the first five years of life in the mid-1960s remained 485 per 1000. Nationally, this proportion was around 300 per 1000. 2,3 The former statistic, at least, represents a level of mortality among infants and children more characteristic of 19th century Asia or 18th century Europe than of the second half of the 20th century. The improvement in child survival achieved since the 1960s is impressive. By the late 1990s under-5 mortality in Niakhar had fallen to about 213 per 1000, while estimates of the proportion of all Senegalese children dying before their fifth birthday fall in the range 115‐130 per 1000. 4,5 Senegal is now one of the lowest mortality countries in tropical Africa. Despite its relative proximity to the capital, Niakhar lies in the region of Senegal with the highest mortality. 3 In particular, in the 1960s the study area combined high mortality in infancy with exceptionally high mortality of children aged 1‐4. This pattern has been found in many parts of Africa and some other tropical regions but it seems to be most pronounced in the Sahel. 6 It was more extreme in Niakhar in the 1960s than in any other population that has been investigated in detail. 3,6,7 In this population, mortality rates rose in the second half of infancy, reaching a peak at about age 12 months, but remained very high right through the second year of life and into the third. This unusual age pattern of mortality was underlain by seasonal variation in numbers of births and deaths. Detailed analysis of the early data from Niakhar demonstrates that the age at which the risk of dying was highest differed according to season of birth: children were experiencing heavy excess mortality during their first two rainy seasons. 8 The overall pattern arose because the peak in mortality was particularly severe for those children aged 9‐15 months during the rains and because this was a relatively large group of children, as the birth rate also peaked at this time of the year. Delaunay et al. propose that under-5 mortality has been declining at a steady rate throughout the 37 years under study. Visual inspection of the relevant Figure in their paper suggests that one could argue equally plausibly that much of the decline in the risk of death occurred during the 1980s, with slower advances being made before and since. It would perhaps be asking too much of the data from a relatively small study, however, to attempt to differentiate between these accounts. It is clear though that it was children aged 6‐30 months that benefited from the early part of the mortality decline. Although mortality in this age range is still higher than is usual, the peak in mortality around one year of age had disappeared by the end of the 1970s. In contrast, the survival of children of all ages has improved during the past two decades. Thus, the explanations of the age pattern of mortality and of mortality decline in this population are closely inter-linked and the causes of mortality decline may differ between the two periods. Two diseases are emphasized in accounts of the age pattern of mortality in childhood in Senegal, of seasonal variations in mortality and of the reduction of mortality: measles and malaria. 1,3,9 The former disease figures prominently in the discussion by Delaunay et al. of the changing age pattern of mortality and the latter in their discussion of the disappearance and re-emergence of the seasonal peak in mortality. Apart from isolated campaigns in the 1960s, however, vaccination coverage in Niakhar began to rise only with the establishment of an EPI programme in the 1980s. 3 It therefore seems unlikely that measles and its sequellae played a significant role in the elimination of the 6‐30 month peak in the risk for dying in Niakhar, which occurred before this date. Moreover, others have argued that more than half the drop in mortality up to 1980 resulted from declining rainfall rather than from human intervention. 9 It was deaths from malaria, and perhaps also diarrhoea, that fell. During the 1980s though, when mortality may have fallen particularly rapidly, the crucial factor does seem to have been improvements in health care, perhaps buttressed by improve

Commentary: 'the child is father of the man.' The relationship between child health and adult mortality in the 19th and 20th centuries.

In the early years of the twentieth century, enormous concern was focused on the relationship between the health of the child and the welfare of the nation. In 1902, Leslie Mackenzie and Matthew Hay informed the Royal Commission on Physical Training (Scotland) that large numbers of children in Aberdeen and Edinburgh were suffering from serious medical conditions which could pose a threat to them in later life, and in 1904 the Interdepartmental Committee on Physical Deterioration devoted more than one-third of its report to conditions affecting the ‘juvenile population’. 1 In 1905 Leslie Mackenzie told the Royal Society of Edinburgh that the most important single lesson to emerge from the enquiries was the need to make the individual citizen fit for the environment around them. ‘One truth we have already realised—if we would fit the man for his environment, we must begin with the child. “The child is father of the man.”’ 2 As this statement indicates, contemporary medical opinion had already begun to emphasize the importance of child health and its relationship to the adult, but it was not until the 1930s that epidemiologists began to devote serious attention to the role which factors operating in early childhood might play in determining the chronological pattern of adult mortality. In 1934, Kermack, McKendrick and McKinlay suggested that if the decline of mortality in England, Scotland, Wales and Sweden in the second half of the nineteenth century was examined in terms of the experience of particular cohorts, then ‘it would seem that the actual calendar year is of relatively little importance in determining … mortality. What is of importance is year of birth of generation or group of individuals under consideration’. They went on to suggest that the first fifteen years of life were particularly important in shaping the health of the adolescent and the adult, and that ‘if the above hypothesis is correct, it would be implied that the decreased death rates were largely the result of … improved physique’. 3 The aim of this paper is to examine the impact of Kermack, McKendrick and McKinlay’s work on subsequent approaches to the history of health and mortality. The paper begins with an examination of the relationship between infant and child health and adult mortality, and focuses on the history of mortality decline in Sweden and Scotland. The second section seeks to extend Kermack, McKendrick and McKinlay’s work on the history of mortality decline in England and Wales back into the eighteenth century, and also highlights some important differences in the relationship between childhood and adult mortality in the case of men and women. The third section examines the impact of their work on the development of research in the field of anthropometric history. The final section will discuss the implications of this work for our understanding, not only of the causes of mortality decline in the past, but also for the projection of mortality trends in the future.