Overdiagnosis in primary care: framing the problem and finding solutions

Abstract

Overdiagnosis, is defined as the diagnosis of a condition that, if unrecognized, would not cause symptoms or harm a patient during his or her lifetime, and it is increasingly acknowledged as a consequence of screening for cancer and other conditions. Because preventive care is a crucial component of primary care, which is delivered to the broad population, overdiagnosis in primary care is an important problem from a public health perspective and has far reaching implications. The scope of overdiagnosis as a result of services delivered in primary care is unclear, though overdiagnosis of indolent breast, prostate, thyroid, and lung cancers is well described and overdiagnosis of chronic kidney disease, depression, and attention-deficit/hyperactivity disorder is also recognized. However, overdiagnosis is a known consequence of all screening and can be assumed to occur in many more clinical contexts. Overdiagnosis can harm patients by leading to overtreatment (with associated potential toxicities), diagnosis related anxiety or depression, and labeling, or through financial burden. Many entrenched factors facilitate overdiagnosis, including the growing use of advanced diagnostic technology, financial incentives, a medical culture that encourages greater use of tests and treatments, limitations in the evidence that obscure the understanding of diagnostic utility, use of non-beneficial screening tests, and the broadening of disease definitions. Efforts to reduce overdiagnosis are hindered by physicians' and patients' lack of awareness of the problem and by confusion about terminology, with overdiagnosis often conflated with related concepts. Clarity of terminology would facilitate physicians' understanding of the problem and the growth in evidence regarding its prevalence and downstream consequences in primary care. It is hoped that international coordination regarding diagnostic standards for disease definitions will also help minimize overdiagnosis in the future.

Fig 1

Disease trajectory and overdiagnosis. The green line depicts the course of true disease, which would progress to threaten health if left untreated. The purple and pink lines depict the course of overdiagnosed disease, which even if left untreated would not progress to threaten health

Fig 2

The impact of changing diagnostic thresholds on screening related overdiagnosis. Without screening, many patients with disease go undiagnosed and many experience harm from disease. Screening with a high diagnostic threshold results in more patients being diagnosed and fewer experiencing harms related to the disease, though more experience treatment related harms, and a small amount of overdiagnosis occurs. Screening with a low diagnostic threshold results in many more patients being diagnosed, among whom many are overdiagnosed, with little harm from disease but more harm related to treatment

Fig 3

Association between overdiagnosis and overuse of medical services

Fig 4

Overdiagnosis in the context of the benefits and harms of prostate cancer screening, reproduced, with permission from Cancer Research UK. PSA=prostate specific antigen