Renal insufficiency and anemia are independent risk factors for death among patients with acute myocardial infarction

BACKGROUND: Chronic kidney disease (CKD) increases risk of death among patients with coronary artery disease. Mortality risks associated with CKD among patients with cardiovascular disease (CVD) are not well defined. Anemia is associated with increased mortality in end-stage renal disease (ESRD) patients and may also increase risk among patients with CVD. METHODS: A random sample of patients admitted to the hospital in a single southern state with a principal diagnosis of acute myocardial infarction (ICD-9 codes 410.xx) were followed up after hospital discharge. RESULTS: CKD was found in 60% of the cohort. Hematocrit of >or=40 was found in 46% of the patients; 26.0% had a hematocrit between 36% and 39%, 21.8% between 30% and 35%, and 5.9% had a hematocrit of less than 30%. The 1-year death rates among individuals with and without CKD were 31.7% and 10.4% respectively [odds ratio (OR) = 4.00 (2.34, 6.91)]. The mortality at one year was 18.6% for individuals with a hematocrit greater than or equal to 40%; 23.5% (OR = 1.35; 95% CI = 0.78, 2.32) for hematocrit 36% to 39%; 30.7% (OR = 1.94; 95% CI = 1.12, 3.34) for hematocrit between 30% and 35%; and 35.8% (OR = 3.16; 95% CI = 1.35, 7.40) for those with a hematocrit less than 30% (chi2 for trend was 12.2, P = 0.007). Both hematocrit and serum creatinine were independently associated with increased risk of death during follow-up after controlling for other patient risk factors. CONCLUSION: CKD and decreasing hematocrit were frequent among older patients hospitalized for acute myocardial infarction and are independent predictors of subsequent risk of death.