What is Evidence-Based Laboratory Medicine

Types of Diagnostic Questions Addressed in Laboratory Medicine 

In the second scenario, the test result excludes a diagnosis this is referred to as a rule-out test. The actions resulting from excluding a diagnosis will invariably involve the evaluation or creation of another hypothesis. When a patient is admitted with atypical chest pain and acute myocardial infarction is suspected, the measurement of troponin maybe used to rule out (or rule in) acute myocardial necrosis. 

The third use of an investigation is for prognosis, which may be considered as the assessment of risk, and complements the diagnostic application. For example, the measurement of human immunodeficiency virus (HIV) viral load foEowing initial diagnosis of HIV infection predicts the time interval before immune cohapse if the condition is not treated. 

The fourth broad use of a test result is concerned with patient management. In a patient with a chronic disease, the result may be used to select the type of intervention and assess the effectiveness of an intervention, and the action will be to change or continue the treatment. In women with metastatic breast cancer, the HER-2/ e status is used to assess the potential usefulness of Herceptin therapy. In a person with diabetes, hemoglobin (Hb) Ai measurements are used to assess glyceraic control and thus the effectiveness of therapy. 

Examples of questions that specify the detail required to accurately qualify the use of a test result are given in Table 13-1. The criteria for a screening test have been established for many years importantly one of the key criteria is that there must be valid treatment available. The clinical episode involves a series of diagnostic questions with binary responses -—a point illustrated in Table 13-1. 

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