Clinical practice guidelines & test consequences 103 3 Introduction Clinicians use medical tests to confirm or exclude a clinical diagnosis (e.g. PCR-test to diagnose COVID-19), to test the likelihood of a certain clinical diagnosis (e.g. PSA-test to screen for risk on prostate cancer) or for follow-up of patients to monitor recovery (e.g. rehabilitation checklists) [1]. Test results guide (treatment) decisions. The clinical value of a medical test depends on various elements: the patient population characteristics (e.g. prevalence of the disease), test characteristics (e.g. sensitivity and specificity) and its downstream consequences (e.g. benefits and harms of treatment) on patient-important outcomes [2]. Clinical practice guidelines (CPGs) provide recommendations to support professionals and patients in clinical decision-making, with the ultimate goal of improving or maintaining patients’ health. In the development of CPGs, the benefits and harms of the interventions of interest are systematically assessed with regard to patient-relevant outcomes. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach is designed to facilitate this process [3]. Diagnostic CPGs provide recommendations about the use of a certain test (or test strategy). Supporting evidence for these recommendations consists of studies about diagnostic accuracy [4].However, acceptable test characteristics (sensitivity and specificity) are not enough to improve patients’ health. CPG developers should also consider downstream consequences (e.g. burden of the test and the proportion of patients with a certain test result who receive the recommended treatment) on patientrelevant outcomes (e.g. mortality, morbidity and quality of life)(see figure 1) [5, 6]. Test-treatment pathway Test consequences Target patient/ population Diagnosis Change in medical decisions Burden of the test Intermediate outcomes Adverse events of treatment/ other tests Change in patient relevant outcomes Testing Testing Decision making Treatment /other tests Association Figure 1.Test-treatment pathway (adapted from Harris et al, 2001) [7] The interpretation of evidence about the value of therapeutic interventions is complex, and there is room for improvement [8]. This applies even more to evidence about diagnostic tests and its translation into CPG recommendations [9-11]. There have been
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