Autopsy statistics on the relative frequency of acute myocardial infarction in the Japanese mental workers and the unemployed during the two oil-crises periods

In order to investigate whether job induced emotional stress, arising from socioenvironmental disasters would act as a trigger for the onset of AMI, the author reviewed all pathological autopsies throughout Japan 15 years old and over. Data were obtained from publications of the 'Annual of the Pathological Autopsy Cases in Japan' for the years 1966-1968 (a period of high economic growth), 1973-1975 (1974, the year of the first oil crisis), and 1978-1980 (1979, the year of the second oil crisis). Relative frequencies of AMI were significantly higher during the years of both oil crises than in both the preceding and following years (2.6% in 1973, 3.7% in 1974, 3.0% in 1975; 2.8% in 1978, 3.2% in 1979, and 2.0% in 1980), and in each of three years of the high economic growth period (1.9-2.2% in 1966-1968). The proportions of managers and officials among AMI victims were significantly higher in the years of both oil crises than in both the preceding and following years (13.4% in 1973, 17.5% in 1974, 12.5% in 1975; 11.6% in 1978, 15.8% in 1979, and 11.1% in 1980). Moreover, there was a significantly higher value in the year of first oil crisis than in each of three years of the high economic growth period (11.7-13.1% in 1966-1968). The proportions of 'out of job' persons were also significantly higher in the years of both oil crises than in the preceding years (24.0% in 1973, 29.3% in 1974, 27.8% in 1975; 24.1% in 1978, 29.1% in 1979, and 27.4% in 1980). For 11,199 randomly selected autopsies, the proportions of AMI in the above two occupational groups were significantly higher in the years of both oil crises than in the preceding years. Moreover, the proportion of 'out of job' persons was significantly higher in the year of first oil crisis than in each of three years of the high economic growth period. A similar trend was noted among professional and technical workers, with more AMI occurring in this group during the years of both oil crises than in both the preceding and following years but without statistically significant difference. However, the proportion of AMI in this group was significantly higher in the year of first oil crisis than in each of three years of the high economic growth period (for managers and officials, 4.1% in 1973, 18.8% in 1974, 7.1% in 1975; 5.1% in 1978, 15.0% in 1979, 6.7% in 1980; 6.7-7.5% in 1966-1968; for 'out of job' persons, 5.0% in 1973, 13.1% in 1974, 6.9% in 1975; 7.2% in 1978, 14.7% in 1979, 10.4% in 1980; 3.2-3.8% in 1966-1968; for professional and technical workers, 7.6% in 1973, 16.1% in 1974, 5.8% in 1975; 7.6% in 1978, 13.7% in 1979, 7.0% in 1980; 4.5-5.3% in 1966-1968). This study not only reconfirms that myocardial infarction tends to occur more frequently in workers under mental stress than in those whose jobs are mostly physical exertion, but also makes it clear that emotional stress, arising from the oil crises would trigger a lethal myocardial infarction in professional workers as well as in 'out of job' persons of Japan.