Effects of age, period and cohort on acute myocardial infarction mortality in Hong Kong

Abstract

Background: Hong Kong has been experiencing a transition from a developing area to a developed area over the past few decades. The time trends of acute myocardial infarction (AMI) mortality would have implications for the future trends of AMI in Mainland China. Methods: Age-adjusted mortality rates during the period 1976–1999 were calculated by direct standardization with the world population using local mortality and population data. Log-linear regressions were used to estimate the annual percentage changes in mortality over different periods. Poisson regression models were used to explore the effects of age, calendar period and birth cohort. Results: A downward trend was observed for age-adjusted AMI mortality rate in both sexes in the 1990s, after the increasing trends in the 1970s and 1980s. The AMI mortality rate among men and women dropped by 36.4% and 37.4%, respectively. A negative annual percentage change was observed across all age groups in both sexes. Both the calendar period and the birth cohort showed significant effects on the changing AMI mortality rate, with the influence of period being stronger than the cohort, especially among males. Conclusion: Age-adjusted AMI mortality started to decrease during the last decade. Changing life styles and a reduction of coronary risk factors could have contributed, but the improvements in medical care and effective treatment for patients suffering from AMI should have an important role.