The association between an elevated cholesterol level and adverse outcomes in the elderly is controversial. Some investigators have found an association between a low cholesterol level and increased mortality in older men. No study has correlated cholesterol levels, as measured during acute coronary events, and long-term clinical outcomes. Foody and associates hypothesize that if total cholesterol levels measured during hospitalization have prognostic value, the strongest association with cardiovascular events in patients would be found in those at highest risk for these events, such as older patients who have had acute myocardial infarction (AMI).
The researchers conducted this study to determine whether total cholesterol levels measured during hospitalization for AMI are an independent prognostic factor for all-cause mortality in an older cohort of persons who survived an AMI.
The study sample consisted of chart reviews from the Cooperative Cardiovascular Project (CCP) pilot. Patients were at least 65 years of age, with a clinically confirmed AMI. The total serum cholesterol level was measured, and demographic and clinical information were recorded. The outcome variable was all-cause mortality within six years of discharge.
Of the 16,182 hospitalizations in the CCP pilot, 4,923 met inclusion criteria for the study and had in-hospital measurement of cholesterol levels. Of these patients, 22 percent had a cholesterol level of at least 240 mg per dL (6.2 mmol per L). Only 6 percent of patients were discharged with a prescription for a lipid-lowering medication.
No association was found between elevated cholesterol level and higher all-cause mortality. Of patients who survived an AMI and had a cholesterol level greater than 240 mg per dL, 17.2 percent died within one year, and 47.9 percent died within six years, compared with 17.4 and 48.7 percent, respectively, of patients with cholesterol levels lower than 240 mg per dL. At six-year follow-up, all-cause mortality was not significantly associated with cholesterol level. There was a slight, nonsignificant trend toward increased mortality in patients with very low cholesterol levels. These results were not altered when excluding patients discharged with lipid-lowering agents.
In this cohort of patients, neither high nor low cholesterol levels obtained during hospitalization for AMI were associated with all-cause mortality at six years. Such measurements in this cohort of patients did not provide prognostic information that is useful in risk stratification. This study analyzed cholesterol measurements performed early after AMI. Thus, even though cholesterol levels can drop markedly after AMI, the levels studied are likely to be a reasonable approximation of patients’ usual levels.
The authors caution that their findings apply only to total cholesterol levels. Fractionated levels were not available for review, and lipid subfractions may provide prognostic information.