Cardiac diagnostics at the YEARS clinic in Berlin

Evidence by disease area

What can prevention actually prevent?

For two disease areas the full chain from measurement to a better outcome is evidenced in randomised trials. For two others it is not. This page states for each which level the evidence reaches — and where it stops.

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2

areas with an evidenced outcome benefit

5

levels from "measured" to "benefits"

6

sources, each linked individually

The short answer

It depends on the disease

For cardiovascular disease and type 2 diabetes, early detection demonstrably prevents something. In both cases randomised trials cover the full chain: a finding leads to a treatment, and that treatment changes the outcome. That is the highest bar you can set for a prevention claim, and here it is met.

For cancer it depends on the organ: for the established programmes there is evidence, for broad imaging in people without symptoms there is not. For dementia the evidence reaches the risk factors and stops short of early detection changing an individual course. Anyone advertising all four areas the same way is confusing an accurate measurement with a benefit.

The yardstick

Five levels from "measured" to "benefits"

A prevention claim can only be judged once it is clear which of these levels it claims. The first four are preconditions. Only the fifth is the benefit.

  1. 1Reliably measured
  2. 2A condition detected
  3. 3Confirmed additional diagnosis
  4. 4A sound treatment decision
  5. 5Actually a better outcome

The full version, with every individual procedure classified, is on our evidence page.

Four areas

Where the chain closes and where it breaks

Cardiovascular disease

Level 5Yes, best evidenced

Here the chain closes completely. Elevated lipid values can be measured reliably, treatment follows a guideline, and the treatment changes the outcome: an analysis of 26 randomised trials with around 170,000 participants shows that lowering LDL cholesterol by 1 mmol/l reduces the rate of major vascular events by roughly a fifth. The same pattern holds for blood pressure. The measurement does not prevent the heart attack — it leads to a treatment that does.

What that does not mean: that every additional cardiac test carries the same benefit. For broad imaging in people without symptoms, that evidence is missing.

In detail on this area

Type 2 diabetes

Level 5Yes, within a clear window

The evidence here is unusually clean, because it reflects exactly the situation in question: people with impaired glucose tolerance, that is, a finding from early detection. Two randomised trials, the US Diabetes Prevention Program and the Finnish Diabetes Prevention Study, both showed that a structured lifestyle programme roughly halves the number of new cases compared with the control group. The finding was the trigger, the intervention the effect.

The benefit depends on something actually following. An HbA1c value in a report with no programme behind it changes nothing.

In detail on this area

Cancer

Level 5 depending on the organPartly, and the differences are large

For the established programmes defined by the Federal Joint Committee there is trial evidence. The largest randomised study of screening colonoscopy to date found fewer colorectal cancers after ten years in the invited group; a statistically significant difference in colorectal cancer mortality did not emerge in that analysis. That is a real benefit and at the same time a reminder of how high the bar for level 5 is.

For whole-body MRI and multi-cancer blood tests in people without symptoms this evidence does not exist. Both therefore sit at evidence tier 3 here and do not replace established screening.

In detail on this area

Dementia

Level 4Reducing risk yes, preventing no

The 2024 report of the Lancet Commission names 14 modifiable risk factors and estimates what share of cases could arithmetically be avoided if they were eliminated across the whole population. That is a sound statement about risk factors. It is not a statement that early detection in an individual without symptoms changes the course — the study linking measurement, treatment and outcome is missing.

Blood-based Alzheimer markers such as pTau217 measure reliably. They sit at evidence tier 3 here, because no treatment follows from a finding in someone without symptoms.

In detail on this area

Sources

No statement without a source

Frequently asked questions

That depends on the disease, and the difference is larger than advertising suggests. For cardiovascular disease and type 2 diabetes the full chain is evidenced: a finding leads to a treatment, and that treatment demonstrably changes the outcome. For cancer this holds for the established screening programmes, not for broad imaging in people without symptoms. For dementia the evidence reaches the risk factors but not an early detection that changes the course in an individual without symptoms. The most common error lies not in choosing the procedure but in the jump from "measured accurately" to "provides benefit".

Because early detection only helps when an effective treatment exists that works better early than late. For cholesterol and blood pressure both are present: effective therapy and a window in which it changes the course. For dementia there is so far no treatment that demonstrably changes the course after an incidental finding in someone without symptoms — which is why such a finding remains information without consequence. The question is never only whether a test finds something, but whether something follows from the finding that helps.

For the part that sits at level 5, yes, and that part is larger than many assume: blood pressure, lipid profile including ApoB and Lp(a), glucose metabolism and cardiorespiratory fitness belong to it. Those values cost little and change something. For the extended procedures the same does not hold with the same clarity, and we say so on every page. If you want to know where you stand for the first time, the robust part is already in the smallest programme. If you are coming purely for the imaging, read first what it can and cannot do.

The evidence page classifies procedures: what a whole-body MRI achieves, what a liquid biopsy achieves, what cardiopulmonary exercise testing achieves. This page applies the same framework to disease areas and asks the reverse question: for which disease does early detection actually produce a better outcome? Both axes belong together, because a well-evidenced procedure can help in one area and not in another. The full version of the evidence tiers and the claim ladder is on the evidence page.

Read on

The individual areas in detail and the framework this page is built on.

Our evidence classification

Every procedure with its evidence, its purpose and an explicit account of what it cannot do.

Heart disease and early detection

The area with the best data, and what follows from it.

Prediabetes

What actually helps after the finding, and what the trials show.

Dementia and lifestyle

Where the evidence is strong and where it explicitly stops.

Cancer screening

The established programmes and the procedures that do not replace them.

Incidental findings

The downside of broad diagnostics, with figures and confidence intervals.

Which part of this is relevant for you?

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