Secular trends in acute coronary syndrome hospitalization from 1994 to 2005

Background — Acute coronary syndrome (ACS) is one of the most frequent reasons for hospitalization worldwide. Although substantial advances have been made in the prevention and treatment of coronary artery disease, their impact on the rates of ACS hospitalization is unclear.

Methods — Data from the Canadian Institute for Health Information Discharge Abstract Database were used to estimate secular trends in ACS hospitalization. A total of 1.3 million ACS hospitalizations in Canada from April 1, 1994, to March 31, 2006, were examined. Overall hospitalization rates were standardized for age and sex using 1991 Canadian census data, and hospitalization rates were also stratified by age group, sex and Canadian province to assess trends in each subgroup.

Results — The Canadian age- and sex-standardized ACS hospitalization rate was 508 per 100,000 persons in 1994, and 317 per 100,000 persons in 2005 – a relative reduction of 37.8% and an average annual relative reduction of 3.9% per year. Declines in ACS hospitalization rates were observed among men (annual relative reduction 3.9%, relative reduction 39.0%) and women (annual relative reduction 3.8%, relative reduction 35.8%). Declining trends were also observed among patients of different age groups and among patients hospitalized across all Canadian provinces.

Interpretation — Over the past decade, a substantial decline in ACS hospitalization rates occurred, which has not been previously observed. This finding is likely due to improvements in primary and secondary prevention of coronary artery disease. The present study's data should provide important insights and guidance for future healthcare planning in Canada.