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Anton E Kunst Department
of Public Health, Erasmus University, PO Box 1738, NL-3000 DR
Rotterdam, Netherlands
Correspondence to: Dr Kunst
kunst{at}mgz.fgg.eur.nl
Abstract Objectives: To compare countries in western Europe
with respect to class differences in mortality from specific causes of
death and to assess the contributions these causes make to class
differences in total mortality.
Introduction Socioeconomic differences in morbidity and mortality have been
observed in all European countries for which data are
available.
1 2
Health inequalities are a common theme in
all European countries, but it is uncertain whether this is a theme
with major variations.
There are several reasons for an interest in the degree to which health
inequalities are similar or dissimilar in the different European
countries. Large dissimilarities would imply that socioeconomic inequalities in health are highly sensitive to specific national circumstances. Further study might show which circumstances are most
influential and could identify circumstances that could be modified
through intervention.
Design: Comparison of cause of death in manual and
non-manual classes, using data on mortality from national studies.
Setting: Eleven western European countries in the
period 1980-9.
Subjects: Men aged 45-59 years at death.
Results: A north-south gradient was observed:
mortality from ischaemic heart disease was strongly related to
occupational class in England and Wales, Ireland, Finland, Sweden,
Norway, and Denmark, but not in France, Switzerland, and Mediterranean countries. In the latter countries, cancers other than lung cancer and
gastrointestinal diseases made a large contribution to class differences in total mortality. Inequalities in lung cancer,
cerebrovascular disease, and external causes of death also varied
greatly between countries.
Conclusions: These variations in cause specific
mortality indicate large differences between countries in the
contribution that disease specific risk factors like smoking and
alcohol consumption make to socioeconomic inequalities in mortality.
The mortality advantage of people in higher occupational classes is
independent of the precise diseases and risk factors involved.
Key messages

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Fig 1.
Probability of men in non-manual and manual
classes dying between the ages 45 and
65
7 9
A second reason relates to the international exchange of research findings and experiences with health policies. An example is the findings from explanatory studies, most of which are from the United Kingdom and Nordic countries. 1 2 Combining research findings from different countries can provide a more comprehensive picture of the causes of health inequalities, but this is possible only to the extent that the patterns and causes of health inequalities are similar in these countries. Some degree of similarity is also required when extrapolating these findings to other parts of Europe.
Several studies have compared countries with respect to the magnitude of inequalities in mortality.3-6 We recently found higher mortality in manual classes than non-manual classes in 11 Western European countries.7-9 For men aged 45-59 years, these mortality differences were approximately equal in most countries; larger differences were observed for Finland and, especially, France (fig 1). Larger differences were also observed for Ireland, but only in absolute terms. Class differences in mortality among men aged 30-44 were relatively large in Finland, Sweden, and Norway (no data for France).7-9
Only a few studies have compared socioeconomic differences in mortality according to cause of death. 3 4 A study that compared Hungary to northern Europe found that the association with educational level was relatively weak for cardiovascular disease but relatively strong for other causes of death.3 This suggested that risk factors for cardiovascular disease (for example, tobacco consumption) made a smaller contribution to mortality differences in Hungary than in northern Europe.
The present study compares 11 countries from the northern and southern part of western Europe. It compares occupational class differences in mortality from specific causes of death and assesses the contributions these causes make to class differences in total mortality among men aged 45-59.
Methods
This study is part of a larger project on socioeconomic differences in morbidity and mortality in Europe. 7 8 Table 1 shows data sources. Data on mortality by occupational class and cause of death were obtained from longitudinal studies or from cross sectional studies. Longitudinal studies consisted of follow up (of a representative sample) of the national population censuses carried out around 1981. Most follow up studies covered the period 1980-9, but Sweden and Italy had shorter periods. The cross sectional studies were of the "unlinked" type,9 with the death registry providing the number of deaths according to occupational class as registered on death certificates and the population census providing the corresponding number of people at risk according to the same occupational classes. All cross sectional studies were centred on the national population censuses around 1981.
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The age group 45-59 years was used for studies that classified men according to their age at death. For longitudinal studies with a follow up period of about 10 years, the birth cohort aged 40-54 years at the start of follow up was used
Nine causes of death were distinguished. As shown in table 2, the share of these causes of death in the total number of deaths varies strongly between European countries. Ischaemic heart disease is the largest single cause of death in northern countries. In France and southern countries, cancers other than lung cancer and gastrointestinal diseases are relatively important. Other causes of death have different international patterns.
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A common occupational class scheme, the EGP (Erikson-Goldthorpe-Portocarero) scheme, was applied to as many countries as possible.10 This scheme was developed to facilitate international comparisons of social stratification and mobility and is therefore particularly suitable for this study. EGP conversion algorithms were applied to individual data on three aspects of jobs: occupational title (by three digit code), employment status (self employed or not), and supervisory status. These conversion schemes could not be applied to the data available for Denmark, Ireland, Italy, Spain, and Portugal, but data from these countries could be made broadly comparable to the EGP scheme at the level of three broad classes: non-manual classes (including self employed men), manual classes, and the class of farmers and farm labourers.
For most countries, there was insufficient information on the former occupation of economically inactive men; these were excluded from the analysis. Because this exclusion is likely to lead to an underestimation of mortality differences between occupational classes, we applied a procedure that gives an approximate correction for this underestimation. 8 9 This procedure is based on a formula that calculates correction factors as a function of the population share and the relative mortality level of the men that had to be excluded from analysis. The adjustment was made for each cause of death separately. The formula was found to perform well in several tests. 8 9
Mortality differences by occupational class were measured by rate ratios and rate differences. Rate ratios compare mortality in manual classes with mortality in non-manual classes. Rate ratios were estimated by means of Poisson regression. The regression model included a term on the contrast between manual and non-manual classes. A series of terms representing five year age groups were added to control for age.
Rate differences were calculated as the absolute difference between mortality in manual and non-manual classes. Mortality rates were adjusted for age by the indirect method, with national age specific mortality rates as the standard. The rate differences for specific causes of death add up to the rate difference for total mortality. Thus, dividing the rate difference for a specific cause of death by the difference for total mortality yields a measure of the contribution that this cause makes to the rate difference for total mortality.
Results
Table 3 presents manual versus non-manual rate ratios for total mortality and broad groups of cause of death. Rate ratios for total mortality are between 1.33 and 1.44, except for Finland (1.53) and France (1.71). Broad cause of death groups show pronounced variations between countries. Differences are small for neoplasms in Sweden, Norway, Denmark, England and Wales, and Portugal; for cardiovascular diseases in Switzerland and the Mediterranean countries; and for external causes of death in Norway, Denmark, Switzerland, and Italy.
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Table 4 presents manual versus non-manual rate ratios for specific causes of death. Mortality from ischaemic heart disease was strongly related to low occupational class in England and Wales, Ireland, and the Nordic countries. France, Switzerland, and Spain showed large differences for cancers other than lung cancer. Class differences in mortality from lung cancer were largest in Finland and Ireland; differences for cerebrovascular disease were largest in England and Wales; and those for gastrointestinal diseases were largest in France and Italy.
Figure 2 presents the contribution that broad groups of causes of death make to the difference in total mortality between manual and non-manual workers. Neoplasms contribute 27-44% of mortality differences in Ireland, France, Switzerland, Italy, and Spain. Cardiovascular diseases contribute 30-54% of the mortality differences in England and Wales, Ireland, and the Nordic countries. The contribution of external causes ranges from less than 10% in Italy and England and Wales to 21% in Sweden, 24% in Finland, and 33% in Portugal.
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Table 5 shows the contributions made by specific causes of death. The north-south gradient in the contribution of cardiovascular diseases can be attributed to ischaemic heart disease. In southern countries, a large part of the mortality difference between manual and non-manual classes is due to cancers other than lung cancer and gastrointestinal diseases. The contributions made by lung cancer were largest in Ireland and Switzerland; those made by cerebrovascular disease were largest in England and Wales, Ireland, and Portugal; and those made by respiratory diseases were largest in Ireland and Portugal.
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Discussion
Reliability and comparability of data
We have identified three major problems with the reliability and
comparability of the available data on mortality by occupational class:
inaccurate distinctions between manual and non-manual classes as
defined in the EGP scheme; biases resulting from the exclusion of
economically inactive men; and biases inherent in "unlinked" cross
sectional studies.
8 9
If these data problems are
different for different causes of death, they will bias the
contribution of causes of death to inequalities in all cause mortality.
In a series of evaluations, we quantified the potential effect that these data problems could have on manual versus non-manual rate ratios.
8 9
The potential size of error was less than 20% in all countries except Ireland, Spain, and Portugal. The magnitude of
error did not vary substantially by cause of death. These errors might
explain some of our results, notably those for Ireland, Spain, and
Portugal, but cannot account for the large variations between countries
seen for several causes of death.
Explaining variations between countries
Relatively large class differences in total mortality occurred in
Finland and, especially, France. Data from a French study showed that
the large differences in mortality from cancers other than lung cancer
and gastrointestinal diseases in that country can be attributed to
cancers of the upper digestive tract and to liver cirrhosis,
respectively.11 These diseases have excessive alcohol
consumption as a common risk factor. This finding implies that alcohol
consumption should be included in explanations of the exceptionally
large class differences in mortality in France.
Implications of crossnational variations
Specific national circumstances seem to be able to strongly
influence the magnitude, pattern, and causes of socioeconomic inequalities in health. The prevalence, at the national level, of risk
factors that have the potential to strengthen the links between
socioeconomic disadvantage and premature death seem to be particularly
important. This was illustrated by the alcohol consumption patterns in
France and Finland. Conversely, mortality differences in Mediterranean
countries seem to have been mitigated by dietary habits and drinking
patterns that traditionally protected men from lower classes against
ischaemic heart disease.
Persistence of the gap in premature death
Despite the large variations between countries in class
differences in mortality from specific causes of death, differences in
total mortality were similar in most western European countries. There
is a parallel with trends over time in northern Europe. Large
socioeconomic differences in total mortality existed when infectious
diseases and other "old" diseases dominated mortality patterns.
Later, when "diseases of affluence" and other degenerative diseases
became the major causes of premature death, the mortality advantage of
higher occupational classes persisted. Higher classes thus seemed to
have changed their life styles and living conditions in ways that
protected them against the new causes of death. This adjustment process
was clearest for ischaemic heart disease.
23 24
Acknowledgments
Members of the EU Working Group on Socioeconomic Inequalities in Health who contributed to this paper are Otto Andersen, Danmarks Statistik, Copenhagen, Denmark; Jens-Kristian Borgan, Statistics Norway, Oslo, Norway; Giuseppe Costa, Environmental Protection Agency, Piedmont Region, Italy; Guy Desplanques, INSEE, Lyon, France; Fabrizio Faggiano, University of Torino, Turin, Italy; Seeromanie Harding, Haroulla Filakti, Office for National Statistics, London, United Kingdom; Maria do R Giraldes, National School of Public Health, Lisbon, Portugal; Christoph Junker, Christoph Minder, University of Bern, Bern, Switzerland; Brian Nolan, Economic and Social Research Council, Dublin, Ireland; the late Floriano Pagnanelli, National Institute of Statistics, Rome, Italy; Enrique Regidor, Ministry of Health, Madrid, Spain; Denny Vågerö, Stockholm University, Stockholm, Sweden;Pekka Martikainen, Tapani Valkonen, University of Helsinki, Helsinki, Finland.
Contributors: AEK, FG, and JPM were involved in writing the paper and carried out the analyses. The other members of the working group participated in developing the design of the study, collecting data, and interpreting the results of analyses. All these coauthors have read the preliminary versions of the manuscript; most of them gave comments, and all approved the final version.
Funding: European Union Biomed-1 programme (grant No CT92-1068).
Conflict of interest: None.
References
(Accepted 5 December 1997)
David A Leon European Centre on Health of
Societies in Transition, Department of Epidemiology and Population
Health, London School of Hygiene and Tropical Medicine, London WC1E 7HT
dleon{at}lshtm.ac.uk
For Britain in particular, the paper by Kunst et al is
timely. In autumn the independent inquiry on inequalities in health set
up by the Labour government is due to report. Its recommendations will
feed directly into a white paper on public health.
Systematic comparison of socioeconomic differences in mortality
across countries has been undertaken only in the past
decade.1-5 There are considerable difficulties in making
such comparisons.
6 7
Each country has tended to use its
own classification of socioeconomic position, and these are not
directly comparable. The study designs have also differed: some
countries have longitudinal studies while others have only cross
sectional data around censuses. Kunst et al resolved the first of these
issues by using a classification of class that was specifically
developed by sociologists for international comparisons.8
Problems and differences in design, however, have not been avoided. As
the authors admit, there may be systematic errors of over 20% in the
estimates of the relative size of social class differences in three
(Ireland, Spain, Portugal) of the five countries that used the cross
sectional approach.
Despite these shortcomings, this paper is based on the most
internationally comparable set of data on social class differences in
mortality ever produced. It is thus frustrating, although
understandable, that many of the estimates are based on deaths that
occurred up to 15 years ago. Over this period inequalities in mortality
have widened considerably in Britain9 and other countries,
and it is not clear whether the international rankings, in particular, are the same in the 1990s as they were a decade earlier.
Although it has been suggested by previous work, the most important
finding of the study is that in each country the strength of
association between social class and mortality varies according to
cause of death. In relative terms, the largest differences are in
deaths from external causes (accidents and violence), while the
smallest tend to be in neoplasms (in northern Europe) and cardiovascular disease (in southern Europe). This variation by cause,
and the fact that it differs across regions of Europe, does not support
a direct link between stress and general susceptibility to disease.
Instead it suggests that specific proximal risk factors, such as
smoking or alcohol, underlie the patterns found in each country. A
public health strategy, however, needs to go beyond urging manual
workers to change their lifestyle and address the complex social,
psychological, and economic factors that underlie these patterns of
behaviour.
In all countries, mortality from all causes is higher in manual
than non-manual social classes. In relative and absolute terms England
and Wales, Finland, and France have the largest social class
differences. Intriguingly, in relative terms, Sweden does not seem to
be doing as well as might be expected given its postwar commitment to
equity. However, if countries are ranked according to the size of the
absolute difference in mortality between classes, as has already been
pointed out,10 Sweden has almost the smallest difference.
From a public health perspective, it is these absolute differences that
are clearly the most important.
At the end, the authors set about considering how it is that upper
social classes seem to be able always to achieve a mortality advantage,
regardless of cause of death. This question is partly generated from
their conclusion that, overall, countries show similar social class
differences. However, this conclusion is at odds with their own
data There is much more to be done to understand the contribution of social
structure, culture, and government policies to the international
variations that Kunst et al have presented. Studying health trends and
public health policies in different countries is an underutilised
strategy that can do much to illuminate the national
situation.13
References
which clearly show appreciable variation across countries. Within
Europe as a whole there is evidence of even greater variation. The
former communist countries of central and eastern
Europe,11 including Russia,12 show larger
socioeconomic differences in mortality than do countries in western
Europe. This, together with the change in size of social class
differences over time, shows that social class mortality differences
are far from fixed.
applied to infant mortality (Australia and Britain).
Soc Sci Med
1990;
30:
1283-1288.
© BMJ 1998