Long-term effects of the Niigata-Chuetsu earthquake in Japan on acute myocardial infarction mortality: an analysis of death certificate data

Izumi Nakagawa ¹, Kazutoshi Nakamura ^2*, Mari Oyama ², Osamu Yamazaki ³, Kazuo Ishigami ³, Yasuo Tsuchiya ² and Masaharu Yamamoto ²

¹ Niigata Seiryo University, Japan
² Niigata University, Japan
³ Niigata Prefectural Government, Japan

^* To whom correspondence should be addressed. E-mail: kazun{at}med.niigata-u.ac.jp.

Accepted 1 June 2009

Abstract

Objective: To determine if the Niigata-Chuetsu earthquake of October 2004 increased long-term mortality from acute myocardial infarction (AMI).

Design: A comparative study of mortality rates before and after the earthquake, as well as between the disaster and control areas, by analyzing death certificate data from October 1, 1999 to September 30, 2007.

Setting: The disaster area and a control area in Niigata Prefecture (n=2,448,025 in October 1, 2004) in Japan.

Population: The total population of Niigata Prefecture observed for five years (12,333,429 person-years) before and three years (7,279,076 person-years) after the earthquake.

Main outcome measures: Mortality from AMI (ICD-10, I21 and I22).

Results: Overall mortality rates from AMI five years before and three years after the earthquake in the disaster area were 47.3 and 53.9 per 100,000 person-years, respectively. Change (+6.6 or +14.0%) was significantly different (P=0.0008), compared to the control area, where mortality rates were 42.5 and 42.6 per 100,000 person-years, respectively, and was not significantly different (P=0.9028). In men, a change in AMI mortality before and after the earthquake in the disaster area was +7.1 per 100,000 person-years (+13.4%, P=0.0172), and +2.0 (+4.2%, P=0.2362) in the control area. In women, a change in AMI mortality in the disaster area was +6.2 per 100,000 person-years (+14.9%, P=0.0184) and -1.6 (-4.2%, P=0.2735) in the control area.

Conclusions: The Niigata-Chuetsu earthquake significantly increased long-term mortality from AMI in both men and women. Clinicians and policymakers in public health must recognize the need for long-term prevention of AMI in earthquake disaster areas.