Educational examples 179 5 (clinical performance) is suitable in principle. This may lead to unjustified healthcare consultation. Screening Screening tests are conducted in asymptomatic individuals to identify a subset of the population for further testing. Their objective is to detect conditions at an earlier stage to enable prompt management, including medical interventions and/or lifestyle adjustments to reduce risks of future events or to maximize treatment effectiveness. Examples include heel prick procedures to detect treatable congenital diseases in neonates, and faecal blood testing for early detection of colon cancer in people aged 55-75 years. Screening tests could be beneficial if early detection of a condition leads to better people-important outcomes and these outcomes outweigh potential (physical and mental) harms of screening. Individuals should be informed about the benefits and harms of screening tests before decision making. To illustrate, a guideline panel may suggest MRI screening as substitute for mammography in women at high risk due to its greater sensitivity [13]. When following the test-management pathway, it becomes evident that drawbacks of such screening should be considered, such as higher costs and potentially larger groups with false positive test results (figure 2b). Moreover, the impact of MRI screening on peopleimportant outcomes, such as breast cancer-related mortality, needs to be evaluated with adequate follow-up time. Diagnostic testing A diagnostic test aims to confirm or exclude a particular disease. Examples include a urine dipstick to detect urinary tract infections, and X-rays to identify bone fractures. The final aim of diagnostic testing is to improve people-important outcomes. The required clinical performance of a test relies on its intended purpose. For diagnosing a condition, the test should have sufficient specificity (i.e. low false positives). Conversely, if the aim is to exclude a diagnosis, the test should have sufficient sensitivity (i.e. low false negatives). We illustrated a test-management pathway for CRP testing in primary care patients with acute cough (figure 2c) [14]. In this scenario, a false-negative test result can lead to an increase of symptoms and complications, rather than a decrease. Additionally, clinicians might still feel uncertain in case of inconclusive test results. Finally, falsepositive testing can lead to undesirable consequences of antibiotic management, such as side effects and antibiotic resistance.
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