Dr. Kumar’s Take
This was a long-term observational study of the general adult population, not a drug trial, so it tells me about association rather than cause. The pattern in the data is a U shape: people at both ends of the LDL range died of cardiovascular disease more often than people in the middle. What I find most clinically interesting is that the two extremes carry different problems. Very low LDL tracked with stroke death, while very high LDL tracked with coronary heart disease death.
- Very low LDL (under 70 mg/dL) was linked to higher risk of death from any cause, from cardiovascular disease, and from stroke, with no increased risk of coronary heart disease death.
- Very high LDL (190 mg/dL or above) was linked to higher risk of death from cardiovascular disease and from coronary heart disease, with no increased risk of stroke death.
I read this as a reason to think about where a patient’s LDL sits in context, and as a signal that the field still needs to define the optimal range for the general population. It is not a reason for anyone on lipid-lowering therapy for established risk to change course on their own.
Brief Summary:
A prospective cohort study followed 14,035 U.S. adults, none of whom had cardiovascular disease or cancer at the start, using data from NHANES III collected between 1988 and 1994. Deaths were tracked through December 31, 2015, giving a median follow-up of 23.2 years. Both ends of the LDL range were associated with higher cardiovascular death:
- Very low LDL (under 70 mg/dL) was associated with higher risk of all-cause, cardiovascular, and stroke death.
- Very high LDL (190 mg/dL or above) was associated with higher risk of cardiovascular and coronary heart disease death.
Key Takeaways:
CVD Risk is Higher at the Extremes:
- Both very low LDL (under 70 mg/dL) and very high LDL (190 mg/dL or above) were linked to higher risk of dying from cardiovascular disease, compared with LDL of 100 to 129.9 mg/dL.
Stroke Risk Sits at the Low End:
- Very low LDL was associated with a 304% higher risk of stroke death. Very high LDL showed no increased risk of stroke death.
Coronary Heart Disease Risk Sits at the High End:
- Very high LDL was associated with a 63% higher risk of coronary heart disease death. Very low LDL showed no increased risk of coronary heart disease death.
Study Design:
The researchers used NHANES III, a nationally representative survey conducted from 1988 to 1994, and included 14,035 adults aged 18 and older who had no cardiovascular disease or cancer at baseline. Mean age was 41.5 years and 51.9% were women. LDL was calculated with the Friedewald equation and split into six groups: under 70, 70 to 99.9, 100 to 129.9, 130 to 159.9, 160 to 189.9, and 190 mg/dL or above. Deaths and their underlying causes came from death record linkage through December 31, 2015, covering 304,025 person-years, during which 4,458 deaths occurred including 1,243 from cardiovascular disease. Weighted Cox proportional hazards models adjusted for age, sex, race and ethnicity, education, socioeconomic status, lifestyle factors, C-reactive protein, body mass index, and other cardiovascular risk factors.
Results:
✔ All-Cause Mortality:
- Very low LDL (under 70 mg/dL) was linked to a 45% higher risk of dying from any cause compared with the reference group (LDL 100 to 129.9 mg/dL).
✔ Cardiovascular Mortality:
- Very low LDL (under 70 mg/dL) was linked to a 60% higher risk of cardiovascular death, and very high LDL (190 mg/dL or above) to a 49% higher risk, both compared with the reference group.
✔ Cause-Specific Mortality:
- Very low LDL was linked to a 304% higher risk of stroke death, with no increased risk of coronary heart disease death.
- Very high LDL was linked to a 63% higher risk of coronary heart disease death, with no increased risk of stroke death.
Related Studies and Research
Statins, LDL, and Low-Carb Diets – Examines the effects of statins on LDL cholesterol in the context of a low-carb diet, highlighting potential benefits and concerns.
Cholesterol Risk Analysis – Analyzes cholesterol metrics beyond LDL, exploring their significance in assessing overall cardiovascular risk.
Conclusion:
Both very low and very high LDL levels were associated with higher cardiovascular death in this cohort, and very low LDL was also associated with higher all-cause and stroke death. The authors conclude that more work is needed to define the optimal LDL range for cardiovascular health in the general population, and I agree with that framing. These are hazard ratios from an observational study: they compare groups against each other, and they do not tell you the absolute chance that any one person will have an event.
