High cholesterol tied to better survival among older adults

Lipid profile loses reliability as an indicator of mortality in older age, with total cholesterol (TC) levels exerting a protective effect against death, a recent study has found. On the other hand, apolipoprotein (Apo) B and A-I levels appear to be better correlates of mortality risk among elderly adults.

The study included data from 98,270 participants (mean age 57.1 years, 46.8 percent women) with available blood measurements from 1985 to 1996. Over an average follow-up of 18.0 years, 30,730 participants died, yielding a mortality rate of 31.3 percent. Of these, 18,135 (59.0 percent) died due to cardiovascular diseases.

Death prevalence increased according to age. The mortality rate was 17 percent among those aged 39–59 at blood measurement, 55 percent among 60–79-year-olds, and 91 percent in those ≥80 years.

Cluster analysis identified three different lipid profiles: normal TC, triglyceride, and ApoB levels with high ApoA-I and low ApoB/ApoA-I (cluster 1; n=35,375); low levels of all biomarkers assessed (cluster 2; n=26,124); and high levels of TC, triglycerides, ApoB, and ApoB/ApoA-I, with low ApoA-I (cluster 3; n=33,210).

Age-specific analysis showed that cluster 3 worsened all-cause mortality in those aged 39–59 years (hazard ratio [HR], 1.17, 95 percent confidence interval [CI], 1.11–1.22) and 60–79 years (HR, 1.07, 95 percent CI, 1.03–1.11), but had no significant impact on mortality in participants ≥80 years. A similar pattern emerged for cardiovascular mortality.

Looking at individual biomarkers, the researchers found that high TC correlated with all-cause mortality risk in those aged 39–59 years (HR, 1.19, 95 percent CI, 1.12–1.27) but had the opposite effect in older age groups (60–79 years: HR, 0.90, 95 percent CI, 0.86–0.99; ≥80 years: HR, 0.86, 95 percent CI, 0.74–0.99).

In comparison, low ApoA-I and high ApoB/ApoA-I both correlated with greater all-cause mortality risk regardless of age.