Trend of Increase in the Incidence of Acute Myocardial Infarction in a Japanese Population: Takashima AMI Registry, 1990-2001

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Abstract
The incidence and mortality of acute myocardial infarction (AMI) remain low in Japan despite major dietary changes and worsening cardiovascular risk factors, a situation that should have resulted in a substantial increase in AMI rates (Japanese paradox). The current trend in the incidence of AMI was examined for the period 1990–2001 by use of data from the Takashima AMI Registry covering a stable population of approximately 55,000 in central Japan. AMI incidence rates (per 100,000 person-years) and 95% confidence intervals were calculated for 1990–1992, 1993–1995, 1996–1998, and 1999–2001. The incidence trend was determined by calculating the average annual change in percentage across the years. There were 352 (men: n = 224; women: n = 128) registered first-ever AMI cases during 1990–2001. The age-adjusted incidence rate of all AMI showed a gradual increase from 39.9 (95% confidence interval (CI): 29.8, 50.0) in 1990–1992 to 62.6 (95% CI: 51.5, 73.7) in 1999–2001. In men, the age-adjusted incidence rate increased from 66.5 (95% CI: 46.4, 86.6) in 1990–1992 to 100.7 (95% CI: 78.6, 122.7) in 1999–2001. In women, fluctuation was observed after an initial steep increase. The average annual incidence increased by 7.6% (95% CI: 3.5, 11.7) among men and by 8.3% (95% CI: 1.02, 15.6) among women. To the best of the authors' knowledge, this is the first study to report an increasing trend of AMI in a Japanese population.