Lead time bias in screening trials artificially increases apparent survival from time of diagnosis. The study design that best controls for lead time bias is:

• A Randomized controlled trial comparing all-cause or cause-specific mortality between screened and unscreened groups ✓
• B Case-control study matching by age at diagnosis
• C Comparing 5-year survival rates in screened vs. unscreened cases
• D Adjusting survival data using mean sojourn time estimates

Explanation

Lead time bias occurs when early detection (screening) advances the time of diagnosis without actually extending life — the patient appears to 'survive longer' from diagnosis only because the clock started earlier. Using survival from diagnosis as the endpoint is vulnerable to this bias. The only design that eliminates lead time bias is an RCT measuring mortality rate (deaths per 1,000 person-years) in screened vs. unscreened populations — because both groups are followed from the same calendar time, regardless of when diagnosis is made. Option D (sojourn time adjustment) partially addresses it but is model-dependent and less robust.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.