Trends in coronary heart disease event rates in New Zealand.

To examine the reasons for the recent decline in coronary heart disease death rates in New Zealand, a register of definite myocardial infarction and sudden death was established in the Auckland region (1981 population 829,464). Both routine and nonroutine case finding sources were used and event rates for the 12 months from March 1, 1981, were compared with estimates from an earlier study conducted in 1974. In 1981, 1,093 myocardial infarction and/or sudden death events in people 25-69 years of age were registered. The age standardized event rates for the total of myocardial infarction and sudden death were 506/100,000 and 139/100,000 for men and women, respectively. Over the seven-year period from 1974 there was no change in the event rate or 28-day case fatality of definite myocardial infarction, but a significant decline in the rate of sudden death occurred from 139/100,000 to 117/100,000. The decline in the sudden death rate was particularly marked in people under the age of 50 years and in subjects with a prior history of myocardial infarction.