Diagnostic Reasoning exam questions and answers fully solved,

Diagnostic Reasoning exam questions and answers fully solved What is sensitivity? - AnswersThe percentage of patients who have a true positive result. Tests with a high sensitivity have a very low percentage of false-negative results, a negative result is likely a true negative. How do you calculate sensitivity? - AnswersTrue Positives / Total # of patients with disease What is the SnNout mnemonic? - AnswersA highly sensitive test is most helpful when the test result is negative. Sensitivity, negative test, rule out. What is specificity? - AnswersThe percentage of patients without the disease who have a true- negative test result. Tests with a very high specificity have a low percentage of false-positive results, therefore a positive result is likely a true negative. How do you calculate specificity? - AnswersTrue negatives / Total # of patients without a disease What is the SpPin mnemonic? - AnswersA highly specific test is most helpful to the clinician when the test is positive Specificity, positive test, rule in. What is a positive likelihood ratio (LR+)? - AnswersThe ratio between the probability of an individual WITH disease having a positive test divided by the probability of an individual WITHOUT disease having a positive test. How do you measure a positive likelihood ratio (LR+)? - AnswersLR+ = sensitivity / 1-specificity What is a negative likelihood ratio (LR-)? - AnswersLR- is defined as the probability of an individual WITH disease having a negative test divided by the probability of an individual WITHOUT disease having a negative test. How do you measure a negative likelihood ratio (LR-)? - AnswersLR- = 1 - sensitivity / specificity What is Fagan's nomogram? - AnswersA graphical tool which, in routine clinical practice, allows one to use the results of a diagnostic test to estimate a patient's probability of having disease. A straight line is drawn from a patient's pre-test probability of disease through the likelihood ratio of the test and it will intersect with the post test probability of disease. What is pre-test probability? - AnswersThe probability of chance of having the disease before the test result is known. This is usually estimated on the basis of the clinician's personal experience, local prevalence data, and published reports. What is post-test probability? - AnswersThe probability of chance of having the disease after the test result is known. This is what clinicians and patients are most interested in as this can help in deciding whether to confirm a diagnosis, rule out a diagnosis, or perform further tests. What is Bayes theorem? - AnswersA theorem that describes how the result of a test (positive or negative) changes our knowledge of the probability of disease. This is done by combining the pretest probability of disease (estimated from clinical experience, local prevalence, etc..) with the LR of the test. Most commonly measured in clinical practice by use of Fagan's nomogram. What is the strength of a test by likelihood ratios? - AnswersThe larger the number of a positive LR (>10), the more likely is the patient to have the disease after a positive test result. The smaller the number of a negative LR- (<0.1), the smaller the risk for disease. What are the steps in the diagnostic process? - Answers1. Identify the problem. 2. Frame the differential diagnosis. 3. Organize the differential diagnosis. 4. Limit the differential diagnosis. Using pivotal points to create a patient-specific differential diagnosis can help narrow the list. 5. Explore possible diagnosis using history and physical exam findings. 6. Rank the differential diagnosis. (Possibilistic, Probabilistic, Prognostic and Pragmatic approach). 7. Test your hypotheses, in o