Hospital mortality after acute myocardial infarction- really an indicator of quality of acute care?

INTRODUCTION: ‘AMI 30-day-mortality using unlinked data’ is reported by OECD as indicator for quality of acute care. It relates to hospital mortality after acute myocardial infarction (AMI, ICD-10: I21-I22). AMI hospital mortality in Germany is among the highest in Europe - indicating major problems in quality of acute care. In contrast, Germany ranks high on health expenditure and availability of cardiologists and PCI facilities. We explain these contradictory findings. METHODS: Literature and public health reports on AMI patient characteristics, acute care, patient registration and healthcare organisation were reviewed. OECD indicators ‘AMI 30-day-mortality using unlinked data’ and ‘average length of stay after AMI’ for European countries were downloaded for 2000-2019. The trend in AMI hospital mortality was described graphically. The influence of average length of stay (LOS) on AMI mortality was assessed by linear regression. RESULTS: Since 2000, AMI hospital mortality fell strongly. In 2019, it was 2.9% in the Netherlands, 3.2% in Norway, but 8.5% in Germany. Different patient characteristics or therapies do not account for the differences in mortality, but health care organization: 1. Day cases are not always included in OECD source data; 2. Average LOS is associated with AMI hospital mortality (R(2)=0.58) and is itself influenced by patient transfer frequency and reimbursement policy; 3. In centralised health systems, AMI patient transfers are more frequent. These factors reduce the registered AMI deaths or increase the number of cases, all resulting in lower hospital mortality. DISCUSSION: AMI hospital mortality is highly influenced by factors that are not related to acute patient care, but to health care organization and patient registration rules. AMI registries reporting hospital mortality include selected AMI patient populations, which hampers valid comparisons. European sentinel registries are needed to validly describe quality of acute care and outcomes in AMI. KEY MESSAGES: • OECD indicator ‘AMI hospital mortality’ does not allow valid conclusions on quality of acute care. • AMI hospital mortality is strongly influenced by patient registration rules and healthcare organization, namely frequency of patient transfers and length of stay in hospital after AMI.