1 Quaternary prevention as a tool to prevent overdiagnosis in the clinical practice

The concept of Evidence-Based Medicine (EBM) does not give clinicians all the answers on how to diminish and prevent overdiagnosis. The concept of quaternary prevention defined as an action taken to protect persons from medical interventions that are likely to cause more harm than good, might be a tool that to some extent can help clinicians with the task of diminishing and preventing overdiagnosis. However, how are EBM, quaternary prevention and the goal of preventing overdiagnosis interrelated? The answer to this question will be debated using three cases in the setting of primary, secondary and tertiary prevention. The strength and limitations of EBM and quaternary preventing when we as clinicians want to avoid or reduce overdiagnosis will also be discussed. Learning goals To learn about the two different concepts: EBM and Quaternary Prevention; Find potential strength and limitations of how quaternary prevention can help clinicians to avoid or reduce overdiagnosis; To acknowledge eventual quaternary prevention risks like, for example, underdiagnosis. Methods A mix of lecture, small group discussion and plenum discussion will be used. Lecture content will include conceptualisations of EBM, quaternary prevention and overdiagnosis. In small groups, participants will be invited to discuss three different clinical cases focusing on the perspective of the potential benefits and harms of each diagnosis in the setting of primary, secondary and tertiary prevention. Plenum discussion will be used to share the main themes revealed in the small groups and three short lectures about the best available evidence in relation to the cases. Expected impact on the participants: By sharing knowledge and experiences, participants are expected to increase their professional resources to deal with the diagnostic challenges in clinical medicine. In no more than 3.5% of asymptomatic individuals, whereas genomic sequencing of the average individual can generate hundreds of variants of uncertain significance. Genetic variants account for no more than 2% to 5% of the variance in many common diseases, and genetic testing, including polygenic risk scores, add little useful information - less than 5 percentage point differences in absolute risk - to traditional population-based, regression-derived risk prediction algorithms in most instances. Even for variants or scores denoting clinically important increase in absolute risk, multiple studies have shown no appreciable response in changed individual behaviour aimed at lowering risk. In contrast, genetic test results, including incidental findings of genes for diseases unrelated to the disease for which the screening was originally intended, can lead to overdiagnosis of ‘pre-disease’ (for which no effective clinical intervention exists), provoking needless anxiety and further unnecessary care. Conclusion Moving from traditional genetic risk profiling, with a focus on rare monogenic disorders within families, to wider polygenetic testing for common diseases in heterogenous populations requires robust evidence of benefits, and minimal harms from overdiagnosis. Establishing an appropriate regulatory environment that mandates rigorous evaluation should a priority for policy-makers.