Long-term impact of socioeconomic status after acute myocardial infarction in Korea.

Background and aims: Socioeconomic status (SES) is known to impact the prognosis of acute myocardial infarction (AMI). However, due to the limited scope of previous studies, this study aimed to investigate the impact of SES on the prognosis of AMI patients within the Korean national healthcare insurance system.

Methods and results: A retrospective cohort study included patients who were diagnosed with AMI between 2007 and 2008 from the Korean National Health Insurance Service and underwent a national health check-up program. Primary endpoint was all-cause mortality. The median follow-up duration was 13.5 years. The SES was divided into tertile scale based on insurance premiums and economic status. Tertile 1 (T1) was the lowest SES, and tertile 3 (T3) was the highest SES. A total of 5971 patients were included, of whom 4329 were employed insured (EI), and 1642 were self-employed insured (SI). After adjusted confounding variables, the Cox-regression model showed SI was associated with worse outcome compared with EI (hazard ratio (HR) [95 % confidence intervals (CIs)], 1.11 [1.02-1.22]). Among individuals in EI, lower economic status showed a trend of worse outcome, but it was not significant (lower tertile vs. higher tertile group, HR [95 % CIs], 1.01 [0.88-1.14]). However, compared with T3 in SI, HRs (95 % CIs) for all-cause death in T2 and T1 were 1.33 (1.09-1.63) and 1.34 (1.10-1.64), respectively.

Conclusion: SES significantly affected the long-term outcome in patients with AMI. SI and lower economic status in SI were associated with a higher mortality rate than EI and higher economic status, respectively. Further investigation of the underlying role of SES in increased mortality after AMI is warranted.