Background Population-based coronary heart disease (CHD) studies have historically focused on myocardial infarction (MI) with limited data on trends across the spectrum of CHD. We investigated trends in hospitalisation rates for acute and chronic CHD subgroups in England and Australia from 1996–2013.
Methods CHD hospitalisations for 35–84 year olds were identified using the primary diagnosis in electronic hospital records from 1996–2013 for England and Australia and from the Oxford Region and Western Australia (WA). CHD subgroups identified were acute coronary syndromes (MI and unstable angina) and chronic CHD (stable angina and ‘Other CHD’). We calculated age-standardised and age-specific rates, and estimated annual changes (95% CI) from age-adjusted Poisson regression separately for 1996–2003 and 2004–2013 to account for non-linear trends. Regional person-linked data from the Oxford Region and WA were used to account for the effect of transfers and coronary procedure admissions on trends.
Results From 1996–2013, there were 4.9 million CHD hospitalisations in England and 2.6 million in Australia (67% men). From 1996–2003, there was between-country variation in the direction of trends in acute coronary syndromes (ACS) and chronic CHD hospitalisation rates (p<0.001). During 2004–2013, reductions in ACS hospitalisation rates were greater than for chronic CHD hospitalisation rates in both countries, with the largest subgroup declines in unstable angina [England: men -7.1%/year (95% CI -7.2 to -7.0), women -7.5%/year (-7.7 to -7.3); Australia: men -8.5%/year (-8.6 to -8.4), women -8.6%/year (-8.8 to -8.4)]. Age-specific trends generally reflected overall downward trends in each subgroup except for MI rates in women aged 35–54 years in 2004–2013, [England: 0%/year (-0.5 to +0.4); Australia: +1.9%/year (+1.4 to +2.4)]. Rates of ‘Other CHD’ increased in 75–84 year olds in both countries. Chronic CHD comprised half of all CHD admissions, with the majority involving angiography or revascularisation. Analysis of linked regional data found increasing MI rates in WA from 2004–2013 for men and women. In both regions, an increasing proportion of admissions for other CHD were for coronary procedures (mainly angiogram) in Oxford (71% in 1996; 84% in 2013) and WA (88% in 1996; 91% in 2013).
Conclusion Since 2004, rates of all CHD subgroups have fallen in both countries, with greater declines in acute than chronic presentations. The slower declines and high proportion of chronic CHD admissions involving coronary procedures requires greater focus. Differing MI trends in younger women in both countries warrant further investigation.
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