Evidence-appraisal glossary
Competing risks
A competing risk is an event that prevents the outcome a study is tracking from ever happening. If researchers follow people to cancer death, a fatal heart attack is a competing risk: once it happens, that person can no longer die of cancer, so it must be handled specially.
Also called: competing events, competing risk analysis, cumulative incidence competing risks.
In time-to-event studies, people are followed until an outcome occurs. A competing risk is a different event that makes the target outcome impossible afterward, such as death from another cause blocking the death being studied.
Why it matters when reading a study. The common Kaplan-Meier method treats competing events as ordinary "censoring," as if those people could still develop the outcome later. They cannot, so this overstates the true risk, sometimes substantially, especially in older or sicker groups where competing deaths are frequent.
What to look for. Check whether authors used a cumulative incidence function (Aalen-Johansen) rather than 1 minus Kaplan-Meier, and for modeling whether they report a Fine-Gray subdistribution or cause-specific hazard. Ask: what competing events existed, and were they acknowledged?
A study reporting only Kaplan-Meier "risk" in a setting with many competing deaths may report inflated numbers. This is an appraisal check on methods, not medical advice.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.