shows bivariate analyses of the association between the metabolic syndrome and each of the explanatory variables, with separate analyses for men and women. Age was a risk factor among women but not men (interaction P < 0.01). Both men and women from lower employment grades were more likely to have the syndrome. We found a dose-response relation between exposure to job stress and the syndrome (trend P < 0.05 for men; P < 0.01 for women). Men with chronic work stress (three or more exposures) were nearly twice as likely to develop the metabolic syndrome than those with no exposure to work stress. Women with chronic work stress were over five times more likely to have the metabolic syndrome, but they formed a small group (n = 18).
Risk factors for having the metabolic syndrome by explanatory variables. Bivariate logistic regression models: complete case analysis
The association between the metabolic syndrome and exposure to health damaging behaviours was stronger among men than women. Poor diet (no fruit and vegetable consumption), heavy alcohol consumption, smoking, and physical inactivity were associated with higher odds of the metabolic syndrome (see ).
Because few men and women had chronic exposure to work stress (three or more exposures) and the evidence for a sex difference in the effect of work stress on the metabolic syndrome was scarce, men and women were combined in the multivariate analysis of the dose-response effect of work stress. Examination of the effects of the interaction between sex and the explanatory variables showed little evidence of sex differences.
shows the results of a series of nested multivariate logistic regression models of the metabolic syndrome. These models use imputed data. The analyses excluded respondents with pre-existing heart disease at baseline and those who had retired at phase 5. In the model with men and women, adjusted for age and employment grade only, greater exposure to work stress was significantly associated with increasing odds of the syndrome. Adjusting for health behaviours did not change the dose-response association. When we excluded obese men and women at baseline (using obesity as a proxy indicator of the syndrome at baseline), the linear association between work stress and the metabolic syndrome remained. When we analysed men and women separately, the pattern of effects was similar, although for women the small number of cases resulted in a non-significant association.
Odds ratios (95% confidence intervals) of the metabolic syndrome. Multivariate multiple imputation logistic regression models: non-retired men and women in the Whitehall II cohort at phase 5
The metabolic syndrome showed a social gradient: men and women in the lowest employment grades had more than double the odds of the syndrome than those in the highest grades (odds ratio 2.33; ). When we adjusted the figures for work stress, the difference in the log odds between the highest and lowest employment grades was reduced by 11%. Adjusting for health behaviours reduced the social gradient by around 16%. When adjusted for health behaviours and work stress the social gradient was non-significant (P = 0.07).
Risk of having the metabolic syndrome by relative index of inequality of employment grade. Multivariate multiple imputation logistic regression models: non-retired men and women in the Whitehall II cohort at phase 5