What makes an appropriate test for preventive health activities?
Medical tests are used for a variety of reasons in primary care
- Diagnostics — to confirm or exclude a particular disease.
- Baseline — to facilitate prescribing.
- Monitoring — to ensure treatment efficacy or track disease progression.
- Screening — to identify early disease before symptoms.
- Risk assessment — to help determine the risk of developing a condition in the future.
During preventive activities testing can be a challenge. Tests are usually requested in the absence of clinical symptoms.1 The choice of test then must be based on the idea that identifying early disease or risk in that person will enable a positive reaction to reduce disease burden or prevent disease development.
Why think twice before testing?
Quality use of medical tests is based on the idea that medical tests are selected based on clinical need: is this the right test for this patient and is this the right time to do it?
The idea is underpinned by a series of quality control questions — are you choosing the most appropriate tests?
- What is my reason for requesting this test?
- Are you confirming disease symptoms?
- Is there evidence to support this test in this patient?
- Are you only ordering the test to allay patient fears?
- Will the test inform my treatment of this patient and improve care?
- Will early detection and treatment of the disease in question actually help the person you are treating?
- Are you prepared to engage in a treatment regimen if the test is positive?
- Will the answer to this test change your treatment or management?
- Is this test asking important questions?
- Does the benefit of testing outweigh the harms?
- Is this the right test for these circumstances?
- How will I interpret the results?
There is a growing understanding that improvements in early detection and widening disease definitions may mean that people with lower risk levels are labelled with disease and may receive treatments that will not provide benefit.2 This issue is defined as overdiagnosis — when asymptomatic people are diagnosed with disease that would not cause them to experience symptoms or lead to early death.
Overdiagnosis — when asymptomatic people are diagnosed with disease that would not cause them to experience symptoms or lead to early death.
Overall the consequence of overdiagnosis may be that people who are healthy or have mild health problems will be labelled as sick. The resulting further investigation or treatment of the condition can cause adverse events that may cause more harm than good.2
This trend in overdiagnosis may be driven by the desire for clinicians to not inadvertently miss a condition that may cause harm.3 This is an understandable viewpoint; no clinician wants to miss a diagnosis that may delay essential treatment for a person with early disease.
However, this desire to ensure no case gets missed may sacrifice the wellbeing of many people. It is important to recognise the fundamental difference between a disease that presents clinically and the same disease that is found because a decision has been made to search for it.3
Tailoring the tests to the person
Preventive activities may reveal family history or symptoms that would make a particular test medically indicated. For example, an assessment of absolute cardiovascular risk including lipid testing would be warranted in a 40-year-old smoker whose father died from a heart attack at 48. In the absence of this family history the benefits of assessing absolute CV risk in a 40-year-old patient may be less clear, which is why the RACGP ‘red book’ recommends assessing patients for absolute cardiovascular risk at age 45 (35 in Aboriginal and Torres Strait Islander peoples). Quality use of medical tests means tailoring testing based on individual patient risk factors and not performing laboratory or other examinations without evidence that a person might be at risk of that condition.
For more information
- The Royal Australian College of General Practitioners. Guidelines for preventive activities in general practice (the red book) 8th edn. Melbourne: RACGP, 2012. www.racgp.org.au/your-practice/guidelines/redbook/ (accessed 8 January 2013).
- Moynihan R, Doust J, Henry D. Preventing overdiagnosis: how to stop harming the healthy. BMJ 2012;344:e3502. [PubMed]
- Hoffman J, Cooper R. Overdiagnosis of Disease, A Modern Epidemic. Arch Intern Med 2012;172.