Preplanned Studies: Case Fatality Rate of Patients with Acute Myocardial Infarction in 253 Chest Pain Centers — China, 2019–2020

Cardiovascular diseases (CVDs) are the leading cause of death worldwide (1) and account for more than 40% of deaths in China (2). Acute myocardial infarction (AMI) is a common and the most serious form of CVD with a high mortality rate (3). The World Health Organization (WHO) monitoring trends and determinants in CVDs MONICA project reported that AMI was the cause of approximately three-quarters of CVD deaths across 37 populations in 21 countries over the past few decades (4). The case fatality rate (CFR) of AMI patients is an important index to reflect the prognosis of AMI. It can provide information on severity of AMI and help determine the focus of secondary prevention (5). A few studies showed that in-hospital CFR of AMI patients in China had decreased in recent years, but most of them were single-city studies with limited geographical coverage or focusing on grade Ⅲ hospitals (5). No studies were carried out to address the post-discharge out-of-hospital CFR. This study used data of AMI patients from 253 chest pain centers (CPC) in China from 2019 to 2020 to estimate the CFR of AMI (6). The study found that the CFR of AMI in-hospital was significantly lower than that of post-discharge out-of-hospital, and the CRF in grade Ⅱ hospitals was higher than that in grade Ⅲ hospitals. In this study, the overall CFR of AMI post-discharge out-of-hospital was 6.0% and grade Ⅲ hospitals was 5.2%. Much more efforts should be made to promote the level of treatment of patients with AMI in grade Ⅱ hospitals.

The study linked patients’ data to China National Death Registration System by unique national identification numbers to obtain the accurate vital status for all patients within CPC. The system collected all deaths outside of hospitals and in hospitals, covering nearly 99% of the counties and districts in China. CPC data was obtained from the CPC reporting system initiated since 2015 and the data quality was improved gradually. We used patients’ data from CPC in 2019 and 2020 when China Chest Pain Center Quality Control Indicators and Assessment Measures (Second Edition) and the China Chest Pain Center Normalization Quality Control Plan were carried out to form a three-level external and internal quality control mechanism for hospitals (6). The study first selected 885 CPCs whose completeness of patients’ ID was higher than 90%. In the next step, CPCs with AMI patients less than 50 in 2019 and 2020 were excluded as some CPCs did not report data from all of their patients. A total of 36,689 AMI patients from 253 CPCs from 23 provincial-level administrative divisions (PLADs) (10 from east, 6 from central, and 7 from west) were included in the analysis. These patients were identified as having ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation myocardial infarction (NSTEMI) by discharge diagnosis. The study also considered both in-hospital and post-discharge out-of-hospital deaths and calculated the 30-day, 60-day, and 90-day CFR of AMI patients by the following formula to define the proportion of patients who died within 30 days, 60 days, and 90 days in all AMI patients admitted to CPCs:

30-day/60-day/90-day CFR = the number of deaths occurring within 30/60/90 days from date of admission to date of death/the number of all AMI patients in CPC

In-hospital death and post-discharge out-of-hospital death were defined according to death’s place in the death certificate. Categorical variables were presented as counts (%). The 30-day, 60-day, and 90-day CFRs of AMI were also calculated in different age groups, sex, AMI types, risk factors, comorbidities and hospital levels. SAS software package (version 9.4; SAS Institute, Inc. Cary, NC, USA) was used for all statistical analyses.

This study included 36,689 patients with AMI, 74.0% were males, 91.4% were older than 45 years, 64.5% were STEMI, and 35.5% were NSTEMI; many AMI patients presented comorbidities, including 2,354 (6.4%) with stroke, 847 (2.3%) with chronic obstructive pulmonary disease (COPD), 249 (0.7%) with cancer, and 6,785 (18.5%) with diabetes mellitus. Overall, 11,638 (31.7%) were from grade Ⅱ hospitals and 25,051 (68.3%) were from grade Ⅲ hospitals (Table 1).

AMI patients’ overall 30-day, 60-day, and 90-day CFRs were 5.9%, 6.9%, and 7.6%, respectively. The CFR increased with age and was higher in females than in males. The 30-day CFR of STEMI was 6.6%, higher than NSTEMI (4.7%). Patients with cancer had the highest CFR on different days. Compared with the grade Ⅱ hospitals, the CFR of AMI patients in grade Ⅲ hospitals was much lower (Table 2).

For post-discharge out-of-hospital deaths, the overall CFR was 6.0%, higher in grade Ⅱ hospitals (7.8%) than in grade Ⅲ hospitals (5.2%), and the 30-day, 60-day, and 90-day CFRs of all AMI patients in grade Ⅲ hospitals were 2.5%, 3.1%, and 3.6%, respectively, which were lower than grade Ⅱ hospitals (3.7%, 4.7%, and 5.5%, respectively) (Figure 1A). For in-hospital deaths, the overall CFR was 4.0% higher in grade Ⅱ hospitals (4.1%) than in grade Ⅲ hospitals (3.9%), and the 7-day, 14-day, and 21-day CFRs were 2.3%, 2.6%, and 2.8%, respectively, which were also lower than grade Ⅱ hospitals (2.7%, 3.1%, and 3.2%, respectively) (Figure 1B).

Figure 1. 

The number of death and case fatality rate (CFR) of acute myocardial infarction (AMI) in post-discharge out-of-hospital and in-hospital of Grade II and III hospitals in China, 2019–2020. (A) The number of post-discharge out-of-hospital death and CFR of AMI in Grade II and III hospitals, China, 2019–2020. (B) The number of in-hospital death and CFR of AMI in Grade II and III hospitals, China, 2019–2020. Notes: Grade II hospitals are generally affiliated with medium size cities, counties, or districts and contain 100–500 beds. Grade III hospitals are generally located in major cities with more than 500 beds and offer the highest-quality care.