Glossary · Methodology
Hazard ratio
In short
The hazard ratio (HR) states how often an event occurs in one group relative to the other, over time. An HR of 0.80 means about 20 percent less often — in relative terms.
A value of 1 means no difference, below 1 less often, above 1 more often. The HR is the standard measure in studies that follow people over a longer period and count when something happens — heart attack, diagnosis, death.
It is a relative figure. An HR of 0.80 can mean 10 instead of 12.5 events per 100 people — or 1 instead of 1.25. What this means for an individual is only shown by the absolute numbers or the number needed to treat.
The HR always comes with its confidence interval. Without it, there is no way to judge how certain the difference is.
The hazard ratio says “how much less often”, not “how often”.
Where this comes up in the fact checks
- Statins – In HOPE-3, cardiac death, heart attack or stroke occurred in 3.7 instead of 4.8 percent, HR 0.76 — the relative and the absolute number side by side.
- Aspirin for prevention – Major bleeding: HR 1.38, at 3.8 versus 2.8 percent.
Sources
Related terms: Relative and absolute effect · Confidence interval · Number needed to treat (NNT)
Information only, not medical advice. The BK-Score is a subjective assessment according to disclosed rules – not a scientific evaluation. Scoring rules