170 Chapter 4 with confidence intervals. The plots are known as coupled forest plots as they contain two graphical sections: one depicting sensitivity, and one specificity. - A SROC plot is a scatterplot of the results of individual studies in ROC space where each study is plotted as a single (specificity, sensitivity) point. - It is clear that the determinants of publication bias for reviews of randomized trials are unlikely to be generalizable to reviews of diagnostic accuracy studies [16, 17]’. QUADAS-2 is a tool that is recommended by Cochrane for use in systematic reviews to evaluate the risk of bias and applicability and mentioned by the GRADE Working Group as a suitable risk of bias tool of primary diagnostic studies [18]. In the GRADE Handbook a chapter is published about the GRADE approach for diagnostic tests and strategies [13]. Some aspects of this chapter that are potentially relevant for the knowledge needed to develop testing recommendations are stated below: - ‘Guideline panels should be explicit about the purpose of the test in question. - Guideline panels and authors of systematic reviews should also clearly establish the role of a diagnostic test or strategy. This process should begin with determining the standard diagnostic pathway – or pathways – for the target patient presentation and identify the associated limitations. - It follows that recommendations regarding the use of medical tests require inferences about the consequences of falsely identifying patients as having or not having the disease. - When diagnostic intervention studies (RCTs or observational studies) comparing alternative diagnostic strategies with assessment of direct patient-important outcomes are available, guideline panels can use the GRADE approach for other interventions. - If studies measuring the impact of testing on patient-important or populationimportant outcomes are not available, guideline panels must focus on other studies, such as diagnostic test accuracy studies, and make inferences about the likely impact of using alternative tests on patient-important outcomes. In the latter situation, diagnostic accuracy can be considered a surrogate outcome for patientimportant benefits and harms. - A recommendation associated with a diagnostic question follows from an evaluation of the balance between the desirable and undesirable consequences of the diagnostic test or strategy. It should be based on a systematic review addressing the clinical question as well as information about management after applying the diagnostic test.
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