A screening programme reports longer survival from diagnosis in screened patients, but there is no difference in mortality. Which bias explains this?
Answer and explanation
Correct answer: D. Lead-time bias
- Step 1: Screening detects disease earlier, so survival from diagnosis is longer even if death is not delayed. Step 2. Total lifespan is unchanged, but the clock starts sooner, so the apparent survival gain is artefactual. Answer: Lead-time bias. Why not the others: Recall bias relates to remembering past exposures. Berkson's bias arises from hospital-based selection. The Hawthorne effect is behaviour change from being observed.
Practise more Statistics and research methods.
Free questions with an explanation for every one, and full timed UKMLA Applied Knowledge Test (MSRA-style single best answer) mock tests.
More Statistics and research methods questions
- In a population of 1000 people, 100 have a disease. A screening test is positive in 80 of the 100 people with the disease and in 45 of the 9…
- In a population of 1000 people, 100 have a disease. A screening test is positive in 80 of the 100 people with the disease and in 45 of the 9…
- In a population of 1000 people, 100 have a disease. A screening test is positive in 80 of the 100 people with the disease and in 45 of the 9…
- In a population of 1000 people, 100 have a disease. A screening test is positive in 80 of the 100 people with the disease and in 45 of the 9…
- A patient has a pre-test probability of disease of 10 percent. A test with a positive likelihood ratio of 16 is positive. What is the approx…
- In a trial, 20 percent of the control group and 15 percent of the treatment group have a stroke over five years. What is the number needed t…