Mortality following acute myocardial infarction (AMI)
Mortality due to coronary heart diseases has declined substantially over the past few decades (see indicator “Mortality from circulatory diseases” in Chapter 3). Reductions in smoking (see indicator “Smoking among adults” in Chapter 4) and improvements in treatment for heart diseases have contributed to these declines. Despite this progress, acute myocardial infarction (AMI or heart attack) remains the leading cause of cardiovascular deaths in Europe, highlighting the need for further reductions in risk factors and care quality improvements (OECD/The King’s Fund, 2020).
A good indicator of acute care quality is the 30-day mortality rate following AMI after hospital admission. The measure reflects the processes of care, such as timely transport of patients and effective medical interventions. However, the indicator is influenced not only by the quality of care provided in hospitals, but also by differences in hospital transfers, average length of stay and AMI severity.
Figure 6.12 shows mortality rates within 30 days of admission to hospital for AMI using unlinked data – that is, only counting deaths that occurred in the hospital where the patient was initially admitted. Across EU countries, the lowest rates in 2017 were in Denmark, the Netherlands, and Sweden (less than 4% of patients aged 45 and over), while the highest rate was in Latvia (over 13%).
Figure 6.13 shows the same 30-day mortality rate but calculated based on linked data whereby the deaths are recorded regardless of where they occurred (i.e. either in the hospital where the patient was initially admitted, after transfer to another hospital or after being discharged). Based on these linked data, the AMI mortality rates in 2017 ranged from 4% in the Netherlands to over 14% in Latvia.
Thirty-day mortality rates for AMI have decreased substantially between 2007 and 2017. Across EU countries for which data are available, they fell by around 30% on average from 9.2% to 6.5% based on unlinked data and from 12.4% to 9.3% based on linked data. Better and more timely access to acute care following an AMI, including timely transportation of patients and admissions in specialised health facilities, such as percutaneous catheter intervention-capable centres, have contributed to the reduction in mortality rates (OECD, 2015).
Mortality rates for patients admitted with AMI vary significantly not only across countries, but also across different hospitals in each country. As shown in Figure 6.14, differences in 30-day mortality rates following AMI across hospitals in each country are often much larger than across countries. In general, a greater volume and concentration of acute care for AMI patients in specialised hospital services is associated with lower mortality rates (Lalloué et al., 2019).
The mortality rate measures the percentage of people aged 45 and over who died within 30 days following admission to hospital for AMI. National rates are age-sex standardised to the 2010 OECD population aged 45 and over admitted to hospital for AMI (ICD-10 codes I21-I22). The rates are also adjusted for co-morbidity and previous AMI (linked data only). The reference population for hospital rates is constructed from data from participating countries (Padget et al., 2019).
Besides differences in the coverage of deaths (numerator), the denominator varies between the indicator using linked and unlinked data. The indicator calculated with unlinked data uses a total number of admissions to hospital with a primary diagnosis of AMI as the denominator. The indicator using linked data uses a total number of patients admitted to hospital with a primary diagnosis of AMI as the denominator. If patients were admitted multiple times, the last admission is counted in the denominator.
Figure 6.14 is a turnip plot that graphically represents the relative dispersion of rates across hospitals in each country. Hospitals with fewer than 50 AMI admissions were excluded to improve data reliability.
References
Lalloué, B. et al. (2019), “Does size matter? The impact of caseload and expertise concentration on AMI 30-day mortality - A comparison across 10 OECD countries”, Health Policy, Vol. 123/5.
OECD (2015), Cardiovascular Disease and Diabetes: Policies for Better Health and Quality of Care, OECD Health Policy Studies, OECD Publishing, Paris, https://doi.org/10.1787/2074319x.
OECD/The King's Fund (2020), Is Cardiovascular Disease Slowing Improvements in Life Expectancy?: OECD and The King's Fund Workshop Proceedings, OECD Publishing, Paris, https://doi.org/10.1787/47a04a11-en.
Padget, M. et al (2019), “Methodological development of international measurement of acute myocardial infarction 30-day mortality rates at the hospital level”, OECD Health Working Papers, No. 114, https://doi.org/10.1787/181be293-en.
Pessoa-Amorim, G. et al. (2020), “Admission of patients with STEMI since the outbreak of the COVID-19 pandemic: a survey by the European Society of Cardiology”, European Heart Journal – Quality of Care and Clinical Outcomes, https://doi.org/10.1093/ehjqcco/qcaa046.
Note: The width of each line represents the number of hospitals with the corresponding rate. Countries are ranked based on the interquartile range of linked data.
Source: OECD Hospital Performance Data Collection 2019.