In-Hospital Case Fatality Rate and Cox Proportional-Hazards Model for Risk Factors of Mortality Due to Myocardial Infarction in Iran’s Hospitals: A National Study

Background: To date, no hospital-based national study with large sample size has been conducted to determine the predictive factors of in-hospital mortality among patients with Myocardial Infarction (MI) in Iran.

Objectives: This study aimed to determine in-hospital Case Fatality Rate (CFR) and hazard ratio of the factors associated with mortality in the patients with MI diagnosis in Iran.

Patients and Methods: In this nationwide, hospital-based, prospective study, the researchers made use of the data of 20750 new MI cases registered by Iranian Myocardial Infarction Registry (IMIR) in 31 provinces between April 2012 and March 2013. Demographic, clinical, and laboratory variables were obtained from the medical records of patients with confirmed acute MI. Cox regression was done by Stata software, version 12 using univariate and multiple analyses through Breslow method. P < 0.05 was considered as statistically significant.

Results: In-hospital mortality rate was 12.1% (N = 2511) and female/male ratio of CFR was 1.36 (95% CI: 1.2 - 1.4). Besides, in-hospital CFR was 8.36: 7.81 - 8.94 in females and 6.12: 5.83 - 6.43 in males. Hazard ratio of mortality for ST segment Elevation Myocardial Infarction (STEMI), chest pain resistant to treatment, and Right Bundle Branch Block (RBBB) was 1.32, 4.06, and 2.45, respectively (P < 0.01). Using Percutaneous Coronary Intervention (PCI) decreased the risk of death in the patients (HR: 0.68). Overall, 83.7% of the patients with STEMI died.

Conclusions: In Iran, identifying the risk factors of mortality due to MI could contribute to detecting high-risk individuals and improving healthcare by relevant planning and interventions in clinics and communities.