overdiagnoses

Overdiagnosis is the diagnosis of a medical condition that would not have caused symptoms, disability, or death if left undiscovered. It most often arises from population screening programs and broad diagnostic testing that identify slow-growing or non-progressive diseases. Unlike a false-positive result, which labels a healthy person as diseased, overdiagnosis correctly identifies a condition that would not have become clinically relevant.

Causes and mechanisms include highly sensitive screening that detects indolent lesions, leading-time and length-time biases that can inflate perceived benefits, incidental findings from imaging, and expanding diagnostic criteria that classify more findings as disease. Overdiagnosis is not synonymous with diagnostic error; it is a consequence of detecting abnormalities that would not have impacted a patient’s health.

Commonly cited examples involve cancer screening, such as prostate cancer detected by PSA testing, breast cancer detected by mammography, and thyroid cancer detected incidentally or by screening. Some detected lesions, such as certain cases of ductal carcinoma in situ or small thyroid cancers, may never progress to cause symptoms.

Consequences include overtreatment with surgery, radiation, or systemic therapy, along with treatment-related harms, anxiety, and increased health care costs. It can also divert resources from patients with more pressing health needs. Measuring overdiagnosis is challenging and often relies on epidemiological modeling and comparisons of incidence and mortality trends.

Mitigation strategies focus on evidence-based, risk-adapted screening guidelines, shared decision-making, selective testing for high-risk groups, and approaches like active surveillance for certain lesions to balance early detection with the avoidance of unnecessary intervention.