Characteristics, readmission patterns and trends in hospitalisations for chronic coronary disease in Western Australia, 2005 to 2022

BACKGROUND: There is increasing clinical focus on chronic coronary disease (CCD) yet limited population-level data on CCD epidemiology. We evaluated admission patterns and characteristics of hospitalised CCD patients and assessed the impact of definitions of episodes of care on CCD surveillance. METHODS: We used person-linked hospitalisation data from Western Australia, 2005-2022, to identify CCD (stable angina, ICD-10-AM I20.1-I20.9; chronic ischaemic heart disease, IHD, I25). Baseline episodes and 28-day, 3-month and 6-month duration-specific episodes were created for each subgroup, stratified by recent acute coronary syndrome (ACS). Age-standardised and sex-stratified hospitalisation rates were calculated, with age-adjusted annual changes estimated from Poisson regression models. RESULTS: From 2005 to 2022, 50,384 stable angina and 65,278 chronic IHD baseline episodes were identified. Nearly 10% had a recent ACS admission. Patient characteristics were similar by subgroup, although chronic IHD admissions were predominantly for invasive angiography +/- revascularisation (95% vs stable angina 61%). When 28-day and 3-month episodes were imposed, stable angina counts were 7.0% and 11.6% lower than baseline episodes, with a similar pattern for chronic IHD (9.2% and 14.6% lower). Most patients had ≥1 coronary-related readmission in the 6-months following their CCD admission (68.2%), with >80% for angiography +/- revascularisation. Marginal declines in overall CCD rates were underpinned by reductions in stable angina (-6.1%/year, 95% CI -6.3, -5.9) and increasing chronic IHD (3.3%/year, 95% CI 3.2, 3.5). CONCLUSIONS: Small declines in CCD hospitalisation rates masked differing trends in stable angina and chronic IHD. Differences in patient management indicate that subgroup stratification is needed when using hospitalisation data for CCD.