Table 3.

Questions that readers of overdiagnosis studies should ask and writers of overdiagnosis studies should address to facilitate better understanding and comparison of results across studies

Study feature	Questions
Definition and measurement	(1)How does this study define overdiagnosis? (2)How does this study measure overdiagnosis? What is the numerator and what is the denominator?
Study design and context	(3)Where was the study conducted? (4)In what years was the study conducted? (5)What were the characteristics of the study population that might affect overdiagnosis (e.g., age range, risk factors for disease, general health status)? (6)What was the screening protocol and what were the criteria for biopsy referral? (7)How compliant were participants with screening and biopsy protocols? (8)What was the incidence in the absence of screening?
Estimation approaches	(9)What estimation approach was used (excess incidence or lead time)? (10)If lead-time approach: Are model assumptions clearly stated and justified? Does model-projected incidence under screening reasonable match observed incidence? What assumptions are made about concurrent disease incidence without screening if this is not observed? (11)If excess-incidence approach: When is study conducted relative to start of screening? Does it include the early years of screening? How is concurrent control incidence projected if this is not observed?