Dr. Kumar’s Take:
A recent systematic review and meta-analysis examined the relationship between cholesterol levels and cardiovascular mortality. While the study confirmed that higher total cholesterol (TC) and low-density lipoprotein (LDL-C) increase the risk of cardiovascular death, it’s crucial to look beyond relative risk. The absolute risk increase remains small, meaning that while cholesterol levels do play a role in cardiovascular health, they may not be as dangerous as they seem at first glance.
Brief Summary:
This meta-analysis compiled data from 14 independent cohort studies, including 1,055,309 participants and 9,457 cardiovascular deaths. Key findings include:
✔ Higher TC is associated with a 27% increase in cardiovascular mortality risk (HR 1.27).
✔ Higher LDL-C is linked to a 21% increase in cardiovascular mortality risk (HR 1.21).
✔ Higher HDL-C is protective, reducing cardiovascular mortality risk by 40% (HR 0.60).
✔ Despite high relative risks, the actual increase in absolute risk is small.
Understanding Relative vs. Absolute Risk:
Many studies report relative risk (RR) or hazard ratio (HR), which shows how much more likely an event is in one group compared to another. However, absolute risk (AR) tells us how much the total risk actually increases.
For example, in this study:
- Baseline absolute risk of cardiovascular death: 0.9%
- Absolute risk for high TC: 1.14% (instead of 0.9%)
- Absolute risk for high LDL: 1.09% (instead of 0.9%)
- Absolute risk reduction for high HDL: -0.36%
Although the relative risks sound high (21-27% increase), the actual increase in risk is only about 0.2%. This means that even if you have high LDL or TC, your overall probability of dying from cardiovascular disease increases only slightly.
Number Needed to Harm (NNH) and Number Needed to Treat (NNT):
Another way to interpret these findings is through NNH and NNT, which measure how many people must be affected by a risk factor (or treated) for one additional harmful (or beneficial) event to occur.
| Lipid Type | Hazard Ratio | Absolute Risk Increase (ARI) | NNH |
|---|---|---|---|
| Total Cholesterol | 1.27 | +0.24% | 412 |
| LDL-C | 1.21 | +0.19% | 529 |
What Does This Mean?
✔ For every 412 people with high total cholesterol, only one additional cardiovascular death occurs.
✔ For every 529 people with high LDL, only one additional cardiovascular death occurs.
✔ The numbers suggest that while high cholesterol increases risk, it’s not a death sentence—most people with high cholesterol will not die from cardiovascular disease.
Key Takeaways:
✔ Relative risks often sound alarming, but absolute risks remain quite low.
✔ To cause one extra cardiovascular death, cholesterol would need to be high in hundreds of people.
✔ While lowering LDL and TC may reduce risk, other factors (like lifestyle and inflammation) likely play a bigger role.
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.
LDL Cholesterol and Heart Health – Discusses the role of LDL cholesterol in cardiovascular disease and evaluates the latest research on its impact on heart health.
Frequently Asked Questions:
Should I be worried if my TC is high but my HDL is also high?
Not necessarily. Your overall lipid balance matters more than any single number.
Does lowering LDL always reduce heart disease risk?
Not always. Studies show that while lowering LDL is beneficial, other factors like inflammation, insulin resistance, and arterial health matter just as much.
What are the best ways to reduce cardiovascular risk?
✔ Exercise regularly
✔ Follow a whole-food, low-inflammatory diet
✔ Avoid processed carbohydrates and excess sugars
✔ Manage stress and sleep quality
Conclusion:
This study reinforces the importance of understanding absolute risk rather than just focusing on relative risk numbers. While high LDL and TC are associated with increased cardiovascular risk, the real-world impact is much smaller than many headlines suggest. Instead of focusing solely on lowering cholesterol, strategies that optimize overall cardiovascular health may offer better protection against heart disease.