Overdiagnosis is a danger to our patients and the health system
Unnecessary testing can use up vital resources and clinician time and — despite sometimes being partly driven by patient expectations — can cause that patient undue anxiety. Stock picture
General practice is one of the cornerstones of healthcare, providing continuity of care, managing undifferentiated presentations, offering large-scale population screening, and long-term management of chronic disease and preventative services. So far so good.
The spectre of underdiagnosis is obvious to all but, in recent years, the concept of overdiagnosis has gained increasing attention in clinical care.
Essentially, overdiagnosis occurs when individuals are diagnosed with conditions that would never have caused significant symptoms, disability, or death.
Unlike misdiagnosis — where the diagnosis is simply wrong or missed — overdiagnosis refers to the correct identification of an abnormality or disease that ultimately does not benefit the patient to know about or treat.
Traditionally, GPs act as gatekeepers to secondary care and the balance between vigilance and restraint is delicate. The pressures of patient expectations, technological advances, defensive medicine, and screening programmes all contribute to an environment in which overdiagnosis has become an unintended consequence of otherwise well-meaning medical practice.
Examples of potential overdiagnosis can arise from systemic, GP, patient and statutory factors.
Screening programmes detect subclinical disease that may not progress. Prostate bloods testing in asymptomatic men is a typical example. While different from overdiagnosis, there is also a risk of false positives — the test shows a problem where there is none — leading to unnecessary worry, investigation, and potentially treatment, and the more unsettling risk of false negatives, where the test does not pick up a real issue. Mammograms have both false positives and negatives.
Expanded and lowered definitions for disorders or diseases create large cohorts of patients labelled with chronic disease, requiring monitoring and treatment, with questionable benefit in many cases. Stage 1 hypertension or high cholesterol in low-risk adults, ‘pre-diabetes’, adult ADHD, mild chronic kidney disease. It is helpful to know who to target risk reduction strategies towards, but the downside is many will be overmedicalised.
Incidental findings are increasingly common with advanced imaging and blood tests. Often a test reveals an anomaly, this can lead to cascade testing to rule out anything sinister. The increased availability of advanced imaging in Ireland (MRI, CT, ultrasound) has led to rising detection of incidentalomas — thyroid nodules, cysts on kidneys, pulmonary nodules — many of which are benign and never clinically relevant. Yet, once identified, they often trigger further testing, referrals, and even surgery.
Similarly, widespread use of routine blood testing, often driven by patient expectation or defensive practice, identifies minor biochemical abnormalities — things such as slightly raised liver enzymes or borderline thyroid function. This can use up vital resources and clinician time and cause undue angst in a patient and foster health anxiety.
GPs, as the frontline providers of information about screening and testing, often face the difficult task of counselling patients on the benefits versus harms of participation. A bone density scan to assess for brittle bones must be interpreted in the broader context of falls risk.
We must also guard against disease-mongering by vested interests in the health arena. Pharmaceutical companies and other agencies (including doctors) create overmedicalisation of normal spectrum physiology. This can include increasingly diagnoses around social anxiety, chronic fatigue, weight control, addictions, and certain behaviours.
Patients often equate more testing with better care. GPs face increasing demands for blood tests, imaging, and referrals. The perception that a thorough doctor is one who orders multiple investigations can create a tension between patient satisfaction and evidence-based restraint.
Unfortunately, Ireland has a high rate of medical litigation. This fosters a culture of defensive medicine, where GPs may overinvestigate or over-refer to avoid the risk of missing a serious diagnosis. While this may protect practitioners legally, it can fuel overdiagnosis and its associated harms.
A very small minority of patients identify themselves through their diagnoses and sometimes they are even self-diagnosed.
I do not believe we are empowering these people with badges of illness. We must be cautious about medicalising both ends of the bell-curve.
Statutory need for ‘diagnostic labelling’ to attain certain benefits, such as invalidity benefit and care allowances, fosters a demand for labels.
So, we have now some idea how overdiagnosis can happen — but what of the consequences? Paradoxically, overdiagnosis may transform healthy individuals into patients.
The psychological impact of carrying a diagnosis — such as ‘mild CKD’, ‘early coronary artery obstruction’, ‘borderline diabetes’ — should not be underestimated. Anxiety, altered self-perception, and stigma can result.
Ageing, it must be remembered, is the greatest cause of pathology. Furthermore, unnecessary treatment exposes patients to side effects without corresponding benefits.
The HSE already struggles with limited GP capacity, long waiting lists for secondary care, escalating healthcare costs and, perhaps, at times, patient expectations.
Overdiagnosis diverts resources away from patients with genuine needs. Additional consultations, referrals, and investigations consume valuable time and money, exacerbating system inefficiencies.
If 10%-plus of children attracted a label of ADHD, then our Camhs service would grind to a halt — perhaps it is already? — excluding other very significant mental health issues such as eating disorders, anxiety, and self-harm. 70% of GP referrals are rejected by Camhs currently.
Should Level 1 autism receive the same funding as Level 3? Should everyone with any cancer get a medical card? Unfortunately, there is a finite budget. Are doctors to decide? Overdiagnosis triggers many ethical dilemmas.
There are ways of limiting overdiagnosis. Shared decision-making is key. GPs should engage patients in informed discussions about the risks and benefits of testing and screening. Tools such as decision aids can help patients understand absolute risk reductions and potential harms, allowing them to make choices aligned with their values. This will, however, increase the complexity and thus time of the consultation.
Public discourse on health often celebrates early detection without acknowledging its downsides.
The increase of subtle direct-to-consumer adverts about health testing, often from private interests, pharmaceutical companies or patient advocacy groups should be resisted: ‘A pill for every ill!’
Campaigns need to play a role in reframing expectations and educating the public about the risks of unnecessary testing.
Increasing advice about exercise, diet, not smoking, weight control, and psychological resilience must begin in primary school. The ‘health industry’ must be careful not to create patients.
Continuing professional development should be introduced via the Irish College of GPs, introducing the concept at undergraduate level, audits, and reflective practice.
The Irish Medical Organisation and the Irish Medical Council have highlighted overdiagnosis as a real concern. Correctly following evidence-based guidelines but also incorporating life expectancy, co-morbidities, and patient preference into decision-making frameworks could help mitigate harm, particularly in older adults.
Fostering an allowance of uncertainty with our GP trainees is important — not every consultation needs to bring a neat diagnosis.
Systemically, GPs often feel pressured by time constraints, litigation risk, and patient expectations. Sometimes we even order tests when we don’t know what to do. A supportive health policy environment — including adequate resourcing of general practice, clear medico-legal protections for evidence-based restraint, and appropriate remuneration models — is essential in avoiding ‘coding-fever’.
Overdiagnosis in general practice represents a nuanced but significant threat to patient wellbeing and system sustainability. While rooted in good intentions — vigilance, thoroughness, and the pursuit of early detection — the consequences are increasingly apparent: Anxiety, unnecessary treatment, misdirection of scarce resources, and ethical dilemmas.
The challenge lies in embracing the subtlety of uncertainty, communicating risks honestly, and prioritising interventions that genuinely improve outcomes.
For GPs, this means exercising clinical judgement not only in recognising disease but also in recognising when not to diagnose but avoiding paternalistic thinking and the resultant bypassing of patients’ concerns.
This paradigm shift in attitudes — for all of us — will take time and increase consultation length at a difficult time in accessing GP care. However, real funding now will save multiples going forward.
By fostering shared decision-making, updating education and guidelines, and addressing the systemic drivers of overdiagnosis, we can move towards a model of care that is not only thorough but also proportionate, patient-centred, economic, and equitable.
- For a further dive into this I would recommend books by two Irish medics and authors — Suzanne O’Sullivan’s , and Seamus O’Mahony’s
- Mike Thompson is a GP based in Midleton, Co Cork.
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