One in four major ischaemic heart disease events are fatal and 60% are pre-hospital deaths: a national data-linkage study (ANZACS-QI 8)

Aims: The aim of this study is to determine proportions of major ischaemic heart disease (IHD) events that are fatal and where they occur, in an era of rapidly falling IHD mortality. Methods and Results: Individual person linkage of national data sets identified all IHD hospitalizations and deaths in New Zealand from December 2008 to November 2010. Outcome measures were proportions of people: (i) hospitalized with IHD and alive at 28 days; (ii) hospitalized with IHD and died within 28 days; (iii) hospitalized for a non-IHD cause and died from IHD within 28 days; and (iv) not hospitalized and died from IHD. Three event definitions were used broad-balanced: IHD deaths and IHD hospitalizations, unbalanced: IHD deaths and myocardial infarction (MI) hospitalizations, and narrow-balanced: MI deaths and MI hospitalizations. About 37 867 IHD hospitalizations and 9409 IHD deaths were identified using the broad IHD definition. Approximately one-quarter of IHD events were fatal: 4% were deaths within 28 days of an IHD hospitalization, 6% were IHD deaths within 28 days of a non-IHD hospitalization, and 14% were non-hospitalized IHD deaths. Using different event definitions, overall case fatality varied from 24–25% (broad and narrow balanced) to 37–39% (unbalanced), whereas the proportion of all deaths that were non-hospitalized was approximately 60%. Forty per cent of deaths were first-ever events that manifested as non-hospitalized IHD deaths. Conclusion: About one-quarter of IHD are fatal, although the proportion is dependent on disease definitions and age. About 60% of all IHD deaths occur out of hospital, and of these 60% are in people not previously hospitalized for IHD.