Clarifying the Direct Relation between Total Cholesterol Levels and Death from Coronary Heart Disease in Older Persons

TLDR

The role of total cholesterol as a risk factor for coronary heart disease in older adults is controversial and requires clarification from controlled trials. The study aims to assess whether prior reports of low cholesterol not being a risk factor in older adults stem from insufficient adjustment for comorbidities and frailty. A multicenter, longitudinal cohort of 4,066 adults aged 65+ from East Boston, Iowa, Washington County, and New Haven was followed for five years, with baseline health interviews and blood samples collected in 1988 and mortality tracked through 1992. When adjusted for established risk factors and frailty, higher total cholesterol levels predicted greater risk of coronary heart disease death, whereas the apparent protective effect of low cholesterol was attributable to comorbidity and frailty.

Abstract

Background: The importance of total cholesterol level as a risk factor for coronary heart disease in older adults is controversial. Objective: To determine whether findings showing that total cholesterol level is not an important risk factor for coronary heart disease in older adults are the result of inadequate adjustment for co-occurring diseases and frailty. Design: Multicenter, longitudinal study with 5-year follow-up for death. Participants: 4066 men and women from East Boston, Massachusetts; lowa and Washington counties, lowa; and New Haven, Connecticut. Measurements: In 1988, participants were interviewed about their health status and had blood samples taken. Mortality follow-up was through 1992. Results: In analyses that included all fatal coronary heart disease events (252 deaths) and did not adjust for risk factors for coronary heart disease and measures of frailty, persons with the lowest total cholesterol levels (≤ 4.15 mmol/L [≤ 160 mg/dL]) had the highest rate of death from coronary heart disease, whereas those with elevated total cholesterol levels (≥ 6.20 mmol/L [≥ 240 mg/dL]) seemed to have a lower risk for death from coronary heart disease (P for trend = 0.04). After adjustment for established risk factors for coronary heart disease and markers of poor health (including chronic conditions, low serum iron and albumin levels) and exclusion of 44 deaths from coronary heart disease that occurred within the first year, elevated total cholesterol levels predicted increased risk for death from coronary heart disease, and the risk for death from coronary heart disease decreased as cholesterol levels decreased (P for trend = 0.005). Conclusions: Elevated total cholesterol level is a risk factor for death from coronary heart disease in older adults, and the apparent adverse effects associated with low cholesterol levels are secondary to comorbidity and frailty. This suggests that excluding older persons from cholesterol screening is inappropriate, but interpretation of screening results in older persons requires clinical judgment. Results from controlled clinical trials are needed to clarify this issue.