Institute:Office of National Coordinator (ONC) Workforce Training Curriculum
Component:The Culture of Health Care
Lecture:Phrasing the clinical question
Harm and prognosis
Slide content:Diagnostic and Therapeutic Thresholds ( Guyatt , 2008) 5.4 Figure: Adapted from Guyatt , Rennie, Meade, & Cook, 2008 7
Slide notes:7 Thresholds are also useful in diagnostics. This figure, from Guyatts [ guy - ihtz ] evidence-based medicine textbook, shows that theres anywhere from a zero-to-one-hundred percent chance that a patient has a disease. Although we typically dont quantify this in routine medical practice, theres actually a threshold at which we decide to test the patient for a disease and a threshold at which we decide to treat the patient. Below the test threshold, we think the disease is so unlikely or perhaps so unimportant that no testing is warranted. At some point, we reach the threshold where we say, We should really get a test to see if the patient has this disease. So, our probability estimate tells us that further testing is required when we exceed the test threshold. As testing proceeds, we may reach a pointand it may not be 100 percentwhere we are highly certain that the disease is present. When we cross over from the test to the treatment threshold, the probability that the patient has the disease is so high that we can make a confident, informed diagnosis and begin treatment. This process is different for different diseases, and the treatment threshold depends on both the benefit and the risk of the treatment. If the treatment for a serious disease has high benefit and relatively low risk, the treatment threshold may actually be lower than if its a treatment that potentially has a lot of adverse effects.