Summary
This report provides a snapshot of almost 35,800 people (aged 25 to 84) who survived an acute coronary syndrome (ACS) hospitalisation, using linked health data with high coverage of the Australian population (National Integrated Health Services Information (NIHSI)). The project looks at interventional procedures and medication use to describe a person’s 'treatment pathway' after an ACS hospitalisation. High-level characteristics and health outcomes are described for those who did and didn’t follow specific treatment pathways. The results provide an insight into patient journeys in reference to existing clinical guidelines (Chew et al. 2016), however they cannot be used to estimate the benefit from treatment pathways for individuals (see note on interpretation).
Acute coronary syndromes (ACS) include heart attacks and unstable angina. These conditions are sudden, severe and life-threatening events. A heart attack (or acute myocardial infarction) is a life-threatening event, commonly where a blocked blood vessel threatens to damage the heart muscle. Angina is a chronic condition in which intermittent episodes of chest pain can occur when the heart has a temporary deficiency in blood supply. Unstable angina can be dangerous due to the changing severity in transient coronary narrowing.
Results are presented separately for the different diagnosis subtypes of acute coronary syndrome:
- ST segment elevation myocardial infarction (STEMI) – 7,853 people (22% of the people included)
- Non-ST segment elevation myocardial infarction (NSTEMI) – 17,109 people (48%)
- Unstable angina – 10,453 (29%)
Note: 1% (369) of the people included had a diagnosis of unspecified myocardial infarction (MI), only limited results are presented for this group due the small size.
This project describes peoples' treatment pathways using 3 measurement points during or after their initial ACS hospitalisation (referred to as the 'index hospitalisation' in this report). These measurement points were:
- Was an interventional procedure (percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG)) undertaken in the index hospitalisation or within 40 days of discharge?&
- Were all 4 classes of guideline recommended medications initiated (defined as being supplied) within 40 days of discharge from the index hospitalisation?
- Were all 4 classes of guideline recommended medications taken persistently, (defined as continuation without a gap in medication supply of 60 days or more) from first supply after hospitalisation until one year after? The first supply could be at any time in the first year, and at least 2 supplies were required. Persistence was not measured for people who died within 1 year of discharge.
Together, each of these measurement points were used to describe a person’s treatment pathway. For example, a treatment pathway may involve having an interventional procedure, being initiated to all 4 classes of medications but then not taking these persistently.
It is important to note that interventional procedures and patterns of medication use are only a component of secondary prevention. Many factors, including some not captured in the analysis, impact both treatment decisions and the risk of experiencing poor health outcomes, for example age, health behaviours, and comorbidities. This project does not identify causal relationships between treatment pathways and health outcomes, but instead provides a starting point for further research and improved understanding of the patient journey.
Key findings
Interventional procedures
During their index hospitalisation (or within the following 40 days) 50% of people who survived an ACS hospitalisation had an interventional procedure (percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG)).
- This varied by subtype; 84% of people with STEMI, 49% of people NSTEMI and 28% of people with unstable angina.
- People who did not have a procedure were more likely to be women, be aged 75-84, live in Outer regional, Remote and Very remote areas or have identified prior coronary heart disease (CHD), across all diagnosis types.
- Of those who survived a STEMI or NSTEMI hospitalisation, fewer people who had an interventional procedure experienced adverse health outcomes in the 3 years after leaving hospital (Major adverse cardiac event (MACE) results for STEMI: 15% for those who received an interventional procedure compared with 22% for those who did not, and for NSTEMI: 19% compared with 28%).
Post-hospital initiation to medication
Only 31% of people filled a prescription for all 4 classes of recommended medications (referred to as initiation in this report) within 40 days of surviving an ACS hospitalisation.
- This varied by subtype; 56% of people with STEMI, 30% of people with NSTEMI and 14% of people with unstable angina.
- People who did not initiate were more likely to be women, be aged 75-84 or have identified prior CHD.
Persistently taking medications
One year after surviving an ACS hospitalisation 22% of people were consistently taking all 4 classes of recommended medications (referred to in this report as persistence).
- This varied by subtype; 37% of people with STEMI, 21% of people with NSTEMI and 13% of people with unstable angina.
- People who did not persist were more likely to be women and be aged 75-84.
A combined ‘treatment pathway’ in the year after hospitalisation
The most comprehensive treatment pathway (including an interventional procedure, initiation to all 4 classes of recommended medications within 40 days and persisted taking them at one year) was most likely for men, the middle-aged or those who lived in metro and inner regional areas.
Of people with a STEMI diagnosis, 27% who survived 1 year had the most comprehensive treatment pathway and generally had better outcomes.
- Almost 1 in 5 people (19%) who experienced the most comprehensive treatment pathway had an emergency cardiovascular disease (CVD) hospital readmission compared to 29% who had the least comprehensive treatment pathway.
- After the first year, 2.4% who experienced the most comprehensive treatment pathway died during follow up compared to 11.6% who had the least comprehensive treatment pathway.
- The groups who followed these different pathways differed by age, sex, socioeconomic group and comorbidities which will have contributed to their prognosis.
References
Chew DP, Scott IA, Cullen L, French JK, Briffa TG, Tideman PA, Woodruffe S, Kerr A, Branagan M, Aylward PEG. (2016) ‘National Heart Foundation of Australia & Cardiac Society of Australia and New Zealand: Australian Clinical Guidelines for the Management of Acute Coronary Syndromes 2016’, Heart Lung and Circulation 25:895–951.