Why Statin NNT Ranges From Ten to Four Hundred

🎧 ▶️ Press the play button below to listen.

Introduction

In the previous article, Statins and Arterial Calcification: The Paradox, we explored a paradox that unsettled many readers: statins can drive up coronary calcium scores while simultaneously reducing heart attacks and strokes.

That contradiction raised a follow-up question that recurred throughout the discussion: how many people need to take a statin for one person to benefit?

That question has a name: the Number Needed to Treat (NNT).

The NNT is not a fixed number. For statins, it ranges from as low as 8–10 in high-risk patients to over 400 in low-risk individuals.

This article explains what the NNT means, why it varies so dramatically, and how it should inform—but never dictate—your decision about whether to take a statin.

What Is the Number Needed to Treat?

The NNT is the number of people who need to receive a treatment for one person to benefit.

Its value lies in translating relative risk reduction—which sounds impressive—into absolute terms, which are more honest.

A “50% relative risk reduction” sounds enormous. But if your baseline risk is only 2%, a 50% reduction means your risk drops from 2% to 1%. That is a 1% absolute benefit. The NNT would be 100.

The NNT is not a guarantee. It describes what happens in a population, not what will happen to you. You cannot know in advance whether you will be the one who benefits.

The Landmark Evidence: Collins et al., The Lancet, 2016

The most widely cited data on statin benefit comes from a 2016 review by Rory Collins and colleagues in The Lancet.

The key finding: lowering LDL cholesterol by 2 mmol/L (77 mg/dL) with an effective statin regimen for 5 years produced dramatically different absolute benefits depending on who was treated.

In 10,000 patients with pre-existing occlusive vascular disease (secondary prevention), major vascular events were prevented in about 1,000 people—an absolute benefit of 10%.

In 10,000 patients at increased risk but without a prior event (primary prevention), major vascular events were prevented in about 500 people—a 5% absolute benefit.

That translates to an NNT of 10 for secondary prevention and 20 for primary prevention.

As the authors put it, lowering LDL by 2 mmol/L for 5 years would typically prevent major vascular events in about 1000 patients with pre-existing disease and in 500 patients at increased risk who have not yet had an event.

How Baseline Risk Changes Everything

The single most important determinant of the NNT is your baseline risk.

The principle is simple: if your risk is already high, a modest relative risk reduction produces a meaningful absolute benefit. If your risk is low, the same relative reduction produces only a tiny absolute gain.

An analogy: seatbelts in two different cars.

Imagine two drivers. Both are given the same safety upgrade—a seatbelt that reduces the risk of death in a crash by 50%.

Driver A drives a small, older car on icy mountain roads at night, without airbags, and regularly travels at highway speeds. Her baseline risk of dying in a crash over the next decade is, say, 20%.

A 50% reduction brings that risk down to 10%. That is a 10-percentage-point absolute benefit. Treat 10 drivers like her with seatbelts, and you save one life. NNT = 10.

Driver B drives a modern SUV with airbags, electronic stability control, and automatic emergency braking, mostly on dry suburban roads during daylight, at modest speeds. His baseline risk of dying in a crash over the next decade is 0.5%.

A 50% reduction brings that risk down to 0.25%. That is a 0.25-percentage-point absolute benefit. Treat 400 drivers like him with seatbelts, and you save one life. NNT = 400.

Same intervention. Same relative risk reduction. Wildly different NNT—because the baseline risk is wildly different.

And notice: nobody would argue that Driver B’s seatbelt is “useless” or that seatbelts “don’t work.” The seatbelt works just as well for him, relatively speaking. It is simply that he was already much less likely to need it.

This is precisely how statins behave. The drug does the same thing in everyone—it lowers LDL and reduces relative risk by a broadly similar proportion. But the absolute benefit, and therefore the NNT, depends entirely on how likely you were to have an event in the first place.

Here is the medical example this time.

A 60-year-old with diabetes, hypertension, and a prior heart attack is Driver A. A healthy 45-year-old with a normal LDL and no other risk factors is Driver B. Both may take the same pill. The NNT is not the same.

The principle is simple: if your risk is already high, a modest relative risk reduction produces a meaningful absolute benefit. If your risk is low, the same relative reduction produces only a tiny absolute gain.

A 2024 meta-analysis of 46 randomized trials involving nearly 238,000 participants found that statins significantly reduced major adverse cardiovascular events with an overall NNT of 31—but this benefit was observed only in individuals with baseline LDL cholesterol of 100 mg/dL or higher.

For someone with a 10-year cardiovascular risk above 20%, the NNT can be as low as 8–10 with high-intensity statins. For someone with a 10-year risk between 7.5% and 20%, the NNT rises to roughly 36–44. At a 10-year risk of 5–7.4%, it climbs to around 69. Below 5%, statins are generally not routinely recommended.

Baseline risk determines everything. This is not a failure of the drug—it is mathematical necessity.

The Other End of the Spectrum: Low-Risk Patients

When the NNT exceeds 100, the conversation changes.

A 2013 letter in The BMJ stated that in low-risk patients older than 60 taking standard statin treatment, the NNT per year to prevent cardiovascular events is 450.

A 2019 response in The BMJ noted that for fit people over 75, the NNT with statins to save one life is 446.

But the most striking figure comes from a 2019 analysis of how statin guidelines have expanded over three decades. Researchers found that the proportion of people over 50 eligible for statin treatment rose from 8% in 1987 to 61% in 2016.

Over that same period, the NNT to prevent one major cardiovascular event rose tenfold—from 40 to 400.

This does not mean low-risk patients should never take statins. It means the arithmetic of the decision is fundamentally different. When the NNT is 400, you are trading a very small chance of personal benefit against the daily cost, potential side effects, and psychological burden of long-term medication.

Statin NNH: Number Needed to Harm

Just as there is an NNT for benefit, there is a counterpart for harm—often called the Number Needed to Harm (NNH).

Muscle symptoms are the most discussed side effect. The Collins review estimated that statin therapy causes symptomatic adverse events—such as muscle pain or weakness—in about 50–100 patients per 10,000 treated for 5 years (0.5–1.0% absolute harm).

Crucially, placebo-controlled trials have shown that most symptomatic adverse events attributed to statins in routine practice are not actually caused by the drug.

New-onset diabetes is another confirmed effect. The same review estimated that treating 10,000 patients for 5 years would cause 50–100 new cases of diabetes.

Myopathy—defined as muscle pain or weakness with large increases in creatine kinase—occurred in about 5 cases per 10,000 treated over 5 years. One of those might progress to rhabdomyolysis if the statin is not stopped.

The balance matters. For high-risk patients, the benefit NNT is low (10), and the harm NNH is high (hundreds or more). The trade-off favors treatment. For low-risk patients, that balance may reverse.

What the NNT Does Not Tell You

The NNT is a powerful tool, but it has clear boundaries.

It is a population statistic. It describes what happens on average in a group, not what will happen to you. An NNT of 100 means 1 person benefits and 99 do not—but you cannot know in advance which one you are.

It cannot predict individual outcomes. You might be the one whose heart attack is prevented. You might also be someone who would have been fine without the drug.

It does not incorporate patient values. Some people are willing to take a daily pill for a small chance of benefit. Others are not. Both positions are rational.

It does not capture the full picture. The NNT does not measure quality of life, cost, or the anxiety of waiting to see whether you benefit.

Statin Decision Making Using NNT

The NNT should be a conversation starter, not a decision-maker.

Ask your doctor three questions:

• What is my baseline risk?
• What is my NNT for benefit?
• What is my NNH for harm?

Know your risk category:

• Are you in secondary prevention (already had a heart attack or stroke)?
• Are you in primary prevention with high risk?
• Are you in primary prevention with low risk?

Consider your values:

• How do you weigh a small chance of benefit against the inconvenience and potential side effects of daily medication?
• How do you feel about taking a drug for years when the odds say you personally may not benefit?

The NNT is a tool for shared decision-making—not a substitute for it.

Conclusion: The Takeaway

• The NNT for statins ranges from 8–10 in high-risk patients to over 400 in low-risk individuals
• The NNT depends on baseline risk, not on the drug alone
• The landmark Collins et al. study found an NNT of 10 for secondary prevention and 20 for primary prevention (for 2 mmol/L LDL reduction over 5 years)
• A 2019 analysis found the NNT rose from 40 to 400 as statin guidelines expanded eligibility over three decades
• For fit people over 75, one estimate puts the NNT to save one life at 446
• Statins cause symptomatic adverse events in about 0.5–1.0% of patients treated for 5 years, but randomized trials show most attributed symptoms are not actually caused by the drug
• The NNT is a population statistic—it cannot predict individual outcomes
• Use the NNT to inform your decision, not to dictate it
• Whether to take a statin should be based on your overall risk, your values, and a conversation with your doctor

Don’t Get Sick!

About Dr. Jesse Santiano, MD

Dr. Santiano is a retired internist and emergency physician with extensive clinical experience in metabolic health, cardiovascular prevention, and lifestyle medicine. He reviews all medical content on this site to ensure accuracy, clarity, and safe application for readers. This article is for educational purposes and is not a substitute for personal medical care.

💡 Support This Work

Creating well-researched articles, maintaining this website, and keeping the information free of charge take time and resources.
If you found this article helpful, please consider donating to support the mission of empowering people to live healthier, longer lives without relying on medications.

🙏 Every contribution, big or small, truly makes a difference. Thank you for your support!

Follow me on Facebook, Gab, Twitter (formerly known as X), Instagram, and Telegram.

Related:

1. ApoB Reveals Hidden Heart Disease And Diabetes Risk Early
2. How to Interpret ApoB and ApoA1 Results
3. ApoB vs LDL Cholesterol: Which Predicts Heart Attacks Better
4. CAC And CTA Scans Help Detect Heart Disease Early
5. ApoB and ApoA1 Best Predict Heart Attack: How To Get Tested
6. ApoB vs LDL Cholesterol: Which Predicts Heart Attacks Better
7. Heart Attack Risk? Use The Framingham Risk Calculator And Lower It Now!
8. Discover Your Cardiac Age with This Free Calculator
9. Heart Rate Recovery Reveals Hidden Secrets About Your Heart
10. Drink Coffee At This Time To Slash Heart Attack Risk
11. The FODMAP Trap That Mimics Heart Attacks During Exercise
12. The Hidden Link Between High Blood Sugar and Heart Attacks
13. Strep From the Mouth and Blood and Sudden Cardiac Death — What You Need to Know
14. Lithium’s Hidden Power: Unlocking Protection Against Cardiovascular Disease
15. How Reduced Blood Sugar Lowers BP And Cardiovascular Risks
16. Cholesterol and Blood Sugar: The Strong Link

References:

1. Byrne, P., Cullinan, J., Gillespie, P., Perera, R., & Smith, S. M. (2019). Statins for primary prevention of cardiovascular disease: Modeling the impact of changes in clinical guidelines. British Journal of General Practice, *69*(683), e373–e380. https://pmc.ncbi.nlm.nih.gov/articles/PMC6532821/
2. Collins, R., Reith, C., Emberson, J., Armitage, J., Baigent, C., Blackwell, L., Blumenthal, R., Danesh, J., Smith, G. D., DeMets, D., Evans, S., Law, M., MacMahon, S., Martin, S., Neal, B., Poulter, N., Preiss, D., Ridker, P., Roberts, I., … Peto, R. (2016). Interpretation of the evidence for the efficacy and safety of statin therapy. The Lancet, *388*(10059), 2532–2561. https://doi.org/10.1016/S0140-6736(16)31357-5
3. García-Gil, M., Blanch, J., Comas-Cufí, M., Daunis-i-Estadella, P., Bolíbar, B., Martí, R., Ponjoan, A., Alves-Cabratosa, L., & Ramos, R. (2018). Effectiveness of statins as primary prevention in people with different cardiovascular risk: A population-based cohort study. Clinical Pharmacology & Therapeutics, *104*(4), 719–728. https://doi.org/10.1002/cpt.945
4. Hawkes, N. (2019). Could giving statins to over-75s really save 8000 lives a year? BMJ, *365*, l1779. https://www.bmj.com/content/365/bmj.l1779
5. Rapid response to: Could giving statins to over-75s really save 8000 lives a year? (2019). BMJ, *365*, l1779. https://www.bmj.com/content/365/bmj.l1779/rr
6. Rapid response to: Bad medicine: statins. (2013). BMJ, *346*, f3566. https://www.bmj.com/content/346/bmj.f3566/rr/649221

Disclaimer:
This article is for educational purposes and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your physician before making health decisions based on the TyG Index or other biomarkers.

© 2018 – 2026 Asclepiades Medicine, LLC. All Rights Reserved
DrJesseSantiano.com does not provide medical advice, diagnosis, or treatment

As an Amazon Associate, I earn from qualifying purchases