Mortality decline in The Netherlands in the period 1850–1992: A turning point analysis

Abstract

The aim of this paper is to give a detailed and fairly objective description of rapid mortality decline in The Netherlands between 1850 and 1992 with respect to the start, end, and phases of the decline. Turning points were estimated for the standardized mortality trend, and for age and sex-specific trends between 1850–1992. The technique used was derived from spline functions. The turning points divided the trends into phases with different paces of decline. Standardized mortality started to decline rapidly in The Netherlands around 1880. Four phases in the period of decline could be distinguished: 1880–1917 (1.2% annually), 1917–1955 (1.6%), 1955–1970 (0.4%), 1970–1992 (1.1%). For nearly all age groups, the most rapid decline occurred in a period comparable to 1917–1955. Causes of death which might have shaped the standardized mortality trend are, among others, respiratory tuberculosis (1917), heart disease (except ischemic) (1955), and ischemic heart disease (1970). Causes of death that shaped the mortality trend are related to trends of determinants of mortality decline. The technique used in this paper can also be applied to other trends e.g. fertility decline.

Introduction

Over the last two centuries, most Western countries have seen enormous demographic and epidemiologic changes: mortality declined enormously, as did fertility, the population grew and disease patterns shifted. These major changes led to the formulation of two important theories, viz. the demographic transition theory and the epidemiologic transition theory. The demographic transition theory explains the population growth in terms of a process in which there is a transition from a stage with high mortality and fertility rates to a stage with low mortality and fertility rates (Beaver, 1975; Caldwell, 1976; Chesnais, 1992).

In the early 1970s, Omran introduced the epidemiological transition theory. This theory can be regarded as a more detailed description of mortality decline in the demographic transition theory. Omran distinguished three stages in the epidemiologic transition. The first stage is the “age of pestilence and famine” in which mortality is high and fluctuating. The second stage is the “age of receding pandemics” in which mortality declines progressively. The rate of decline accelerates as epidemic peaks become less frequent and eventually disappear. The third stage is the “age of degenerative and man-made diseases” in which mortality first continues to decline and eventually approaches stability at a relatively low level. The dominating causes of death of this stage are cardiovascular diseases, cancer and external causes of death (Omran, 1971; Omran, 1983). The demographic and epidemiologic transitions have been observed in many countries albeit with differences in start, development and duration of the transitions.

Fig. 1 shows the demographic transition as observed in The Netherlands (Hofstee, 1981). It suggests that crude mortality rates had been declining slowly since the beginning of the 19th century and started to decline rapidly around 1875.

The aim of this paper is to give a detailed description of the period of rapid mortality decline in The Netherlands, or more specifically, to describe the start of rapid mortality decline, the phases in the decline in terms of changes in the pace of decline and the end of rapid mortality decline. A description of sex and age-specific mortality changes as well as cause-specific mortality changes is given to elucidate possible sex-specified, age-specific and cause-specific developments in mortality that might have shaped the total mortality trend.

The turning points in the mortality trend described in this paper are not based on a simple visual inspection of the trend, but on a more formal statistical method. A so-called turning point analysis was used to determine phases with different paces of mortality decline. The Netherlands provide a good opportunity for such an analysis because the quality of historical mortality and population data in The Netherlands can be considered as good in comparison to many other Western countries. Ever since 1865 medical doctors have been legally required to issue a medical certificate stating the cause of death, which was then given to the Registrar (van Poppel, 1997).

The advantage of a formal statistical method and reliable data is that these will generate more objective results, and thus provide a sound basis to relate changes in mortality to changes in determinants of mortality.