Lead-time bias

When lead time bias or the lead time distortion ( English time lead bias ) is a distortion, in the early detection of diseases , such as cancer screening plays a role. It describes an apparently longer survival time when the time of diagnosis is brought forward compared with patients who are only diagnosed after clinical symptoms . If no effective therapy is available, the benefit of the corresponding screening is irrelevant - that is, the diagnosis is made earlier and the patient only apparently lives longer after the earlier diagnosis, but overall no gain in life can be ascertained.

The falsification by the lead time bias can only be determined in randomized controlled studies if the survival time of the screened persons is no longer than that of the unscreened persons. The error cannot be detected in the normal implementation of screening programs.

Other important possible sources of error in medical studies, which endanger the transferability of their results to everyday medical practice, are confounders , selection bias , and misclassification .

See also

• Overdiagnosis bias

Individual evidence

1. ^ Robert H. Fletcher: Clinical Epidemiology: The Essentials; Lippincott Williams 2013 p. 160

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