Stress, and its role in illness - V
The last study we report on (reference 8), involves a large study of about 30,000 Japanese men and 43,000 Japanese women, ages 40 to 79, who completed a lifestyle questionnaire that included perception of mental stress. After approximately 8 years of followup, in which stoke, CHD and total cardiovascular diseases (CVD) were tracked, they found that in women, a high level of stress leads to a factor of two higher risk of mortality from stroke and CHD, and a 1.5-fold increase in risk for CVD. The actual results are:
Risk Ratio of 2.2, for stroke. (1.5 to 3.1 Margin of Error).
Risk Ratio of 2.3 for CHD. (1.1 to 4.4 Margin of Error).
Risk Ratio of 1.6 for CVD. (1.3 to 2.1 Margin of Error).
Interestingly, the results for men show only a very small increase in risk with stress, that is not statistically siginificant. This should not be construed to imply that men are less impacted by stress than women. More than likely it is an artifact of the way that stress was evaluated in this cohort: 75% of the men had a full time job at the start of the study, but only 32% of the women had a job. Possibly, a large part of the male population was stressed by their work, and so the difference between high and low stress was not large. Alternatively, the men may not have admitted their true level of stress. This exemplifies once again the difficulties with these types of studies, that involve subjective assessments.