32 comorbidities at admission, clinical, electrocardiographic, and laboratory evidence of AMI, heart failure, percutaneous coronary intervention (PCI), and death in 30 d after admission. All these patients met at least two of the criteria: (1) clinical symptoms consistent with AMI (chest pain, arm or shoulder pain, dyspnea, diaphoresis, nausea or vomiting); (2) dynamic electrocardiographic changes consistent with AMI; and (3) elevation of cardiac biomarkers, such as cardiac troponine, creatinine kinase and its isoenzyme muscle-brain subfractions. Patients were categorized into 4 groups based on the number of medical comorbidities (0, 1, 2, ≥ 3). Patients without medical comorbidity were defined as the reference group. The 30-day in-hospital mortality was calculated for each group. 2.2 Comorbidity Medical comorbidities at admission included hypertension, diabetes mellitus, previous myocardial infarction, valvular heart disease, chronic obstructive pulmonary disease (COPD), renal insufficiency, previous stroke, atrial fibrillation and anemia. These coexisting medical conditions at admission were identified, and the number of medical comorbidities was calculated for each patient. 2.3 Statistical analysis The gender and mortality rate were treated as categorical variables. Cox regression analysis was used to examine the relationship between the number of medical comorbidities at admission and 30-day in-hospital mortality. Relative risks (RRs) and 95% confidence intervals (CIs) were calculated with adjustment for age, gender, heart failure and PCI using SPSS 16.0 software (SPSS, Chicago, IL, USA). A P value of < 0.05 was considered statistically significant. 3 3.1 Results Characteristics of patients The 5161 AMI patients aged from 18-103 years, with a mean age of 63.9 ± 13.6 years. Of the 5161 AMI patients, 4133 patients were male, and 1028 patients were female; Yang XD et al. In-hospital mortality in patients with AMI 74.6% of the patients had at least one medical comorbidity; 2 615 (50.7%) patients had hypertension, 1 237 (24.0%) had diabetes mellitus, 619 (12%) had old myocardial infarction, 366 (7.1%) had atrial fibrillation, 223 (4.4%) had renal insufficiency, 218 (4.2%) had valvular heart disease, 172 (3.3%) had old cerebral infarction, 60 (1.2%) had anemia, and 52 (1%) had pulmonary heart disease. 3.2 30-day in-hospital mortality The 30-day in-hospital mortality of all 5161 AMI patents was 9.3%. The 30 d in-hospital mortality in patients with only one comorbidity at admission was 7.2%, which was higher compared with that in patients without comorbidity (4.9%), but the difference was not statistically significant (RR: 1.21, 95% CI: 0.901.64, P = 0.209). The 30-day in-hospital mortality in AMI patients with 2 comorbidities was 11.1%, which was significantly higher than that in patients without comorbidity (RR: 1.41, 95% CI: 1.131.77, P = 0.003). The 30-day in-hospital mortality in AMI patients with ≥ 3 comorbidities was 20.3%, which was even higher than that in patients without comorbidity (RR: 1.95, 95% CI: 1.592.39, P = 0.000) (Table 1, Figure 1). 4 Discussion AMI is a common health problem worldwide and the incidence of AMI increased with age.[5] Patients hospitalized with AMI, especially the elderly patients, tend to have multiple chronic cardiac or noncardiac medical conditions, such as hypertension, diabetes mellitus, renal insufficiency or chronic COPD. Untill now, how these comorbid diseases affect the early outcome of patients with AMI has not been fully investigated. As previously reported, renal insufficiency[6,7] and anemia[8] were considered as an independent predictors for poor prognosis of AMI. However, the previous studies had focused on the effect of one single comorbidity on the outcome of patients with AMI, which was not consistent with the fact that patients with AMI often had more than one comorbidity. In the present study, we sought to better understand the scope of this problem in the Table 1. The 30-day in-hospital mortality in AMI patients with or without comorbidities. Group Control Group 1 Group 2 Group 3 Number of medical comorbidities 0 1 2 ≥3 AMI: acute myocardial infarction. Number of patients (n) Number of 30-day in-hospital death (n) 30-day in-hospital mortality (%) Total 1 312 1 914 1 225 710 Male 1 125 1 583 923 502 Female 187 331 302 208 Total 62 137 136 144 Male 40 107 103 101 Female 22 30 33 43 Total 4.7 7.2 11.1 20.3 Male 3.6 6.8 11.2 20.1 Female 11.8 9.1 10.9 20.7 Journal of Geriatric Cardiology | jgc@mail.sciencep.com; http://www.jgc301.com