This study showed that there were marked sex differences in physical health functioning in populations from Britain, Japan and Finland and, and in mental functioning in populations from Britain and Japan (i.e. men had better health than women). No sex differences in mental functioning were observed in the Finnish population. In addition, the sex differences in physical and mental functioning were smaller among the Finnish employees than among other 2 populations. Sex differences in work characteristics were also observed in all populations but the pattern of the sex differences were somewhat different among the 3 populations: Japanese women with the same age and employment grade as men simply had disadvantaged work characteristics (i.e. high job demands and long work hours), while British women had 2 disadvantaged and 1 advantaged work characteristics (i.e. low job control, high job demands, and not long work hours), and Finnish women had 2 advantaged and 1 disadvantaged work characteristics (i.e. not low job control, high job demands, and not long work hours) than men. These findings suggest that sex inequalities in work characteristics were also somewhat smaller in the Finnish population than in other 2 populations. In addition, the larger the sex differences in work characteristics, the larger the sex differences in health and the reduction in the sex differences in health after adjustment for work characteristics, which suggests that sex differences in work characteristics contribute to the sex differences in health and the international variation.
The findings from this study are consistent with those from previous research on sex differences in poor physical and mental health (Macintyre et al., 1996
; Lahelma et, 1999
; Doi & Minowa, 2003
). With respect to sex differences in mental health, the findings from this study were similar to those from a recent study on sex differences in depression in 23 European countries (Van de Velde et al., 2010
): The sex differences in depression were smaller in Nordic countries than in other countries, with no significant sex differences in Finland. In most countries, depression levels most strongly related to socioeconomic position (i.e. labour market position, educational level and household income). In this study, sex differences in employment grade and working conditions were the smallest in the Finnish population. Such smaller sex differences in employment position and working conditions may contribute to no significant sex differences in mental health among the Finnish employees.
According to Esping-Andersen (1990)
, Finland belongs to the social democratic group among the welfare states regimes with a strong emphasis on universal and egalitarian policies, while Britain and Japan belong to liberal and conservative welfare state regimes respectively. The Global Gender Gap Report (Hausmann, et al., 2008
) showed that, among the 3 countries, Finland achieves the highest gender equality in terms of economic participation and opportunity, educational attainment, political empowerment and health and survival. Relatively smaller sex differences in health and work characteristics in the Finnish population may be partly attributable to the egalitarian policies in Finland. The findings from this study may be therefore explainable from the existing data.
In this study, when SES was adjusted for, the sex differences in work control declined, whereas the differences in job demands and long work hours strengthened among women in all populations. We recently reported that high SES individuals generally had high control, high demands, and long work hours in our previous study of the 3 civil servant populations (Sekine, et al., 2009
). Because more men occupied higher employment grades than women in all populations, making adjustment for SES may result in the improvement in work control and the worsening in high demands and long work hours among women. Thus, the changes in the sex difference in work characteristics after adjustment for SES may be explainable from the male predominance of high employment grade.
In this study, when SES was adjusted for, the sex differences in physical functioning slightly attenuated in all populations. This attenuation may be attributable to the fact that there were SES differences in physical functioning (i.e. the higher the employment grade, the better the health) and more men than women occupied higher grades of employment. In contrast, changes in the sex differences in mental functioning after adjustment for SES differed among the 3 countries. Like in physical functioning, the sex differences in mental functioning attenuated in the Japanese population; the sex differences increased in the Finnish population; the sex differences hardly changed in the British population. The different sex patterns may be attributable to different patterns of SES differences in mental functioning. In the Japanese population, the majority of women occupied low SES which are associated with poor mental functioning so making adjustment for SES may have resulted in the reduction in sex differences in mental functioning. In contrast, in the Finnish population, low SES had better mental functioning so making adjustment for SES may have resulted in the increase in the sex differences. In the British population, there were no consistent SES differences in mental functioning so making adjustment for SES may have resulted in no significant changes in the sex differences. While the different patterns on SES differences in mental functioning in the Finnish population deserve further research, the patterns were the same as those reported in our previous study of the 3 civil servant populations (Sekine, et al., 2009
In this study, when work characteristics were adjusted for, the sex differences further attenuated in both physical and mental functioning in all populations. In addition, the largest reductions in the sex differences in both physical and mental health were observed in the Japanese population. These findings may be attributable to the facts that psychosocial stress at work (low control and high demands) and short and long work hours were generally associated with poor physical and mental functioning and Japanese women tended to have more disadvantaged work characteristics than those of other 2 countries. In contrast, the smallest reduction in the sex differences was observed in the Finnish population. This may be attributable to the facts that Finnish women did not necessarily have more disadvantaged work characteristics than men and Finnish women occupied relatively higher employment grade than those of other 2 populations.
There are several methodological limitations. Firstly, this study is cross-sectional, which makes it hard to determine the causal nature of the associations of sex, SES, psychosocial stress and work hours with physical and mental functioning. However, there is little evidence for an effect of poor physical and mental health on employment grade changes in the British civil servants study (Chandola, Bartley, Sacker, Jenkinson & Marmot, 2003
Secondly, it may be difficult to generalize the results of this study as the participants were recruited from occupations and regions that may not be representative of whole populations in the countries and this study contained only 3 countries. While the British and Finnish populations came from capital cities of those countries, the Japanese population came from a non-metropolitan area. The civil servants were middle-aged, well-educated, and white-collar dominant in comparison to the general adult population. Also, gender equality policies are introduced in this population of Japanese civil servants. Thus, sex inequalities in health may be larger in the general adult population. In addition, it should be mentioned that long work hours and high job stress were more prevalent among men than among women in a nationally representative sample of Japanese adults (Ministry of Internal Affairs and Communications, 2007
; Ministry of Health, Labour and Welfare, 2010
). Further investigation is necessary.
Thirdly, there may be data comparability problems. There were the 10-year differences in data collection. The working style has changed (e.g. computerisation) during the 10 years. We did not use the data from a later phase of the Whitehall II study, because the study was set up in 1985 for those aged 35-55 at the time of survey (Marmot et al., 1991
) and about half of them had already retired when the Japanese and Finnish data were collected in early 2000s. In addition, the results from making adjustment for SES in the Japanese population should be treated cautiously due to the very small number of high grade female employees. There may also be data comparability problems for grades of employment, work characteristics and health measures, although the factor scores from the US population have been widely used for Japanese population (Fukuhara et al., 2001
) and the items pertaining to the job demands and control were carefully chosen.
Fourthly, we did not adjust for other factors such as factors that affect reporting, family-related factors, health behaviours, and biological factors as explanatory factors for sex differences in health. Consideration of these factors may result in further explanation of sex differences in health in each country and the cross-national variation.
In conclusion, we observed that more women than men had poor physical and mental functioning with one exception for mental functioning in the Finnish population. In addition, more women than men tended to have disadvantaged work characteristics but there were relatively smaller sex differences in work characteristics in the Finnish population. The larger the sex differences in work characteristics, the larger the sex differences in health and the reduction in the sex differences in health after adjustment for work characteristics. These results suggest that egalitarian and gender equal policies may contribute to smaller sex differences in health, through smaller differences in disadvantaged work characteristics between men and women.