Gender differences in protective effect of HDL cholesterol in older adults
MedWire News: High levels of high-density lipoprotein (HDL) cholesterol and apolipoprotein (apo)A-I are protective against all-cause mortality in men, independent of glycemic level, and in women with Type 2 diabetes, show results of an Italian study.
"Our results are in contrast with those reported in a recent review, showing a consistent inverse association between HDL cholesterol and cardiovascular disease (CVD) risk in both men and women," say Marianna Noale and co-authors, from the Consiglio Nazionale delle Ricerche Institute of Neuroscience in Padova.
Using data from the Italian Longitudinal Study on Aging, the researchers evaluated the relationship between plasma lipids, lipoproteins, and other metabolic factors, and their role in predicting fatal events, among 2422 individuals who were aged 65-84 years.
Study participants were categorized into three subgroups according to their baseline fasting glucose level: normal fasting glucose (NFG; glucose <100 mg/dl; n=1423), impaired fasting glucose (IFG; glucose ≥100 mg/dl but not with Type 2 diabetes; n=697); and Type 2 diabetes (n=302).
To determine factors predicting death at follow-up in each of the subgroups, the researchers performed factor analyses, which reduced 10 predictive variables into four individual factors.
The major factors identified for both men and women were: insulin resistance (HOMA-IR, fasting insulin, and fasting glucose), body size (body mass index and waist circumference), total cholesterol (total cholesterol apoA-I, and triglycerides), and HDL cholesterol (apoA-I and HDL cholesterol).
As reported in the journal Nutrition, Metabolism, and Cardiovascular Diseases, 149 fatal events were observed among men and 139 among women over a mean 3.4 years of follow-up.
Among men, the "HDL cholesterol" factor was inversely associated with fatal endpoints in those with NFG, IFG , and Type 2 diabetes. Indeed, higher levels were seen to have a protective effect, with respective hazard ratios (HR) of 0.79, 0.59, and 0.55.
In women, levels of HDL cholesterol were inversely associated with fatal endpoints only in those with Type 2 diabetes (HR=0.61). Among women with NFG, the "body size" factor was a significant predictor of fatal endpoints (HR=0.74 for low vs high). No other factors showed significant associations.
"We know that HDL cholesterol concentrations decrease in males during puberty and early adulthood, and thereafter remain lower than those in women," explain the authors. "This trend could explain why low HDL cholesterol levels is a risk factor for mortality in men, independently from other risk factors, while in women, at advanced age, is a risk factor only in those with Type 2 diabetes and, therefore, with a cluster of other risk factors."
The researchers conclude: "Future studies are required to find strategies to mimic the positive effects of HDL cholesterol and of apoA-I and to prevent the negative effects of aging on these cardioprotective factors in the aged population."
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By Nikki Withers