Heart attacks and the Newcastle earthquake

Abstract

OBJECTIVE: To test the hypothesis that stress generated by the Newcastle earthquake led to increased risk of heart attack and coronary death. DESIGN: A natural experiment. SUBJECTS: People living in the Newcastle and Lake Macquarie local government areas of New South Wales, Australia. INTERVENTION: At 10.27 a.m. on 28 December 1989 Newcastle was struck by an earthquake measuring 5.6 on the Richter scale. OUTCOME MEASURES: Myocardial infarction and coronary death defined by the criteria of the WHO MONICA Project and hospital admissions for coronary disease before and after the earthquake and in corresponding periods in previous years. Well established, concurrent data collection systems were used. RESULTS: There were six fatal myocardial infarctions and coronary deaths among people aged under 70 years after the earthquake in the period 28-31 December 1989. Compared with the average number of deaths at this time of year this was unusually high (P = 0.016). Relative risks for this four-day period were: fatal myocardial infarction and coronary death, 1.67 (95% confidence interval [Cl]: 0.72, 3.17); non-fatal definite myocardial infarction, 1.05 (95% Cl: 0.05, 2.22); non-fatal possible myocardial infarction, 1.34 (95% Cl: 0.67, 1.91); hospital admissions for myocardial infarction or other ischaemic heart disease, 1.27 (95% Cl: 0.83, 1.66). There was no evidence of increased risk during the following four months. CONCLUSION: The magnitude of increased risk of death was slightly less than that previously reported after earthquakes in Greece. The data provide weak evidence that acute emotional and physical stress may trigger myocardial infarction and coronary death.