Knowledge of the likelihood that a screening-detected case of cancer has been overdiagnosed is vitally important to make treatment decisions and develop screening policy. An overdiagnosed case is an excess case detected by screening. Estimates of the frequency of overdiagnosis in breast and prostate cancer screening vary greatly across studies. This article identifies features of overdiagnosis studies that influence results and shows their effect by using published research. First, different ways to define and measure overdiagnosis are considered. Second, contextual features and how they affect overdiagnosis estimates are examined. Third, the effect of estimation approach is discussed. Many studies use excess incidence under screening as a proxy for overdiagnosis. Others use statistical models to make inferences about lead time or natural history and then derive the corresponding fraction of cases that are overdiagnosed. This article concludes with questions that readers of overdiagnosis studies can use to evaluate the validity and relevance of published estimates and recommends that authors of studies quantifying overdiagnosis provide information about these features.

The Kidney Disease: Improving Global Outcomes (KDIGO) organization developed clinical practice guidelines in 2012 to provide guidance on the evaluation, management, and treatment of chronic kidney disease (CKD) in adults and children who are not receiving renal replacement therapy.

Many blood tests have been proposed as alternatives to liver biopsy for identifying fibrosis or cirrhosis.

The role of aspirin in thromboprophylaxis after total hip arthroplasty (THA) is controversial.

Meaningful use, as defined by the Centers for Medicare & Medicaid Services, will require the aggregation of patient data to enable population assessment. Little is known about the proportion of physicians who are able to meet meaningful use criteria or their use of electronic health records (EHRs) to manage patient populations.

Sunscreen use and dietary antioxidants are advocated as preventives of skin aging, but supporting evidence is lacking.

Outcomes of treating gestational diabetes mellitus (GDM) are not well-established.

A 50-g oral glucose challenge test (OGCT) is a widely accepted screening method for gestational diabetes mellitus (GDM), but other options are being considered.

Update of the 2004 U.S. Preventive Services Task Force (USPSTF) recommendation statement on screening and behavioral counseling interventions in primary care to reduce alcohol misuse.

Update of the 2005 U.S. Preventive Services Task Force (USPSTF) recommendation statement on screening for HIV.