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Thread: [Diagnosis] Diagnostic Series

  1. #1

    Cool [Diagnosis] Diagnostic Series

    A Summary of the Diagnosis Process

    1.Take a history: Elicit symptoms and a timeline; begin a problem list.

    2.Develop hypotheses: Generate a mental list of anatomic sites of disease, pathophysiologic processes, and diseases that might produce the symptoms.

    3.Perform a physical examination: Look for signs of the physiologic processes and disease suggested by the history, and identify new findings for the problem list.

    4.Make a problem list: List all the problems found during the history and physical examination that require an explanation.

    5.Generate a differential diagnosis: List the most probable diagnostic hypotheses with an estimate of their pretest probabilities.

    6.Test the hypotheses: Select laboratory tests, imaging studies, and other procedures with appropriate likelihood ratios to evaluate your hypotheses.

    7.Modify your differential diagnosis: Use the test results to evaluate your hypotheses, eliminating some, adding others, and adjusting the probabilities.

    8.Repeat steps 1 to 7: Reiterate your process until you have reached a diagnosis or decided that a definite diagnosis is neither likely nor necessary.

    9.Make the diagnosis or diagnoses: When the tests of your hypotheses are of sufficient certainty that they meet your stopping rule, you have reached a diagnosis. If uncertain, consider a provisional diagnosis or watchful waiting. Decide whether more investigation (return step 1), consultation, treatment, or watchful observation is the best course based upon the severity of illness, the prognosis, and comorbidities. If the diagnosis remains obscure, retain a problem list of the unexplained symptoms and signs, as well as laboratory and imaging findings, assess the urgency for further evaluation and schedule regular follow-up visits.



    Any illness or abnormality for which a patient could seek medical attention (or a colleague, consultation) can be broadly encompassed by the statement above. The differential diagnosis is developed by delineating the chief concern(s) or primary aberrant signs, and selecting a relevant mixture of disease processes and organ systems. The differential can be narrowed by determining subjective and objective detail surrounding the chief concern. The differential can be broadened by expanding each major category into subcategories.

    References:

    1. Benbassat, J., & Bachar-Bassan, E. (1984). A comparison of initial diagnostic hypotheses of medical students and internists. Journal of medical education, 59(12), 951–956.
    2. Bowen, J. L. (2006). Educational strategies to promote clinical diagnostic reasoning. The New England journal of medicine, 355(21), 2217–2225. doi:10.1056/NEJMra054782
    3. Coderre, S., Mandin, H., Harasym, P. H., & Fick, G. H. (2003). Diagnostic reasoning strategies and diagnostic success. Medical education, 37(8), 695–703.
    4. Fulop, M. (1985). Teaching differential diagnosis to beginning clinical students. The American journal of medicine, 79(6), 745–749.
    5. Graber, M. L., Tompkins, D., & Holland, J. J. (2009). Resources medical students use to derive a differential diagnosis. Medical teacher, 31(6), 522–527.
    6. Sapira, J. D. (1981). Diagnostic strategies. Southern medical journal, 74(5), 582–584.
    Last edited by admin; Mon 22nd May '17 at 11:25pm.
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  2. #2
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    Default Symptoms

    A symptom is an abnormal sensation perceived by the patient. Insist that the patient describes their symptoms; do not accept diagnoses or medical jargon as substitute. Record the symptoms using the patient's words. Evaluation of symptom can be straightforward, as when the patient says, "I've found a lump in my neck" (symptoms), and the examiner can palpate a mass (physical sign). However, when the patient complains of a nonspecific symptom, such as chest pain, more information is required.

    Question the patient about other symptoms specific for processes and diseases you are considering, either to support or undermine a hypothesis. For example, when the patient complains of chest pain, ask if it is related to respiratory movements. A positive answer prompts questions about inflamed muscles, fractured ribs, and pleurisy. If the answer is negative, ask for an association with exertion or radiation suggestive of angina pectoris. Thus, each step leads to another, resulting in refinement of your hypotheses.
    Last edited by admin; Wed 13th January '16 at 9:07pm.
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  3. #3

    Default Re: [Diagnosis] Diagnostic Series

    Well, the brief steps in diagnostic examination include:

    Step 1 Generate a problem list - from the history and physical examination (this topic has a lot common with the steps in thread "[Clinical Skills] Therapeutics Planning" at http://www.tomhsiung.com/wordpress/2...tics-planning/)

    Step 2 List possible diagnoses - based upon the most probable anatomic sites and pathophysiologic process explaining the problems.

    Step 3 Differentiate the probabilities of each disease (pretest probability) on your list for this patient, differential diagnosis - using the specific characteristics of this patient

    Step 4 Choose tests (laboratory and imaging) with appropriate likelihood ratios to test the above hypotheses and the results change the probability of each hypothesis/diagnosis to a post-test probability: some are now much more probable, whereas others are much less probable.

    Step 5 The clinician returns to the patient, reviews the history, and repeats specific parts of the examination to reach a new, refined differential diagnosis to be tested more specifically. This process repeats, each time returning to the patient for their ongoing history and to search for new or changing physical findings, until one ore specific diagnoses are established that fully explain the patient's illness.
    Last edited by Janis.Y.Chen; Fri 15th April '16 at 11:32pm.
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    PharmD Year 1 TomHsiung's Avatar
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    Default Re: [Diagnosis] Diagnostic Series

    The three basic questions to be answered by diagnosis are:

    1.What is happening to me and why? (explanation)
    2.What does this mean for my future? (prognosis)
    3.What can be done about it and how will that change my future? (therapy)
    B.S. Pharm, West China School of Pharmacy, Class of 2007, Health System Pharmacist, RPh. Hematology, Infectious Disease.

  5. #5

    Default Re: [Diagnosis] Diagnostic Series

    5-Step Patient-Centered Interviewing

    [Diagnosis] Diagnostic Series-screen-shot-2016-07-09-at-2-58-08-pm-png
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    Default Re: [Diagnosis] Diagnostic Series

    Interpretation of Frequency (Sensitivity)
    Because the frequency of findings (e.g., physical exams, lab findings, etc. We assume it to be a sign is this post) provide just information about a sign's sensitivity, they can only be used to support a statement that a physical sign, when absent, argues against disease.

    The absence of any finding whose sensitivity (or frequency) is greater than 95% is a compelling argument against that diagnosis (i.e., the negative LR is =<0.1, even if the specificity of the finding, which is unknown, is as low as 50%).

    For example, the frequency of elevated neck veins in patients with constrictive pericarditis is 98%. So in this example, elevated venous pressure is such a finding (with very high sensitivity, 98%): if the clinician is considering the diagnosis of constrictive pericarditis but the patient's beside estimate of venous pressure is normal, the diagnosis becomes very unlikely.

    Similarly, the absence of two or three independent findings having sensitivities greater than 80% is also a compelling argument against disease.

    Interpretation of EBM (evidence-based medicine) Diagnostic Information (EBM Box)
    To use EMB boxes, the clinician need only glance at the LR columns to appreciate the discriminatory power of different findings. LRs with the greatest value increase the probability of disease the most; LRs with the value closest to zero decrease the probability of disease the most. Boldface type highlights all findings with an LR of 3 or more or of 0.3 or less, thus allowing quick identification of the physical signs that increase probability more that 20% to 25% (LR>=3) and those that decrease it more than 20% to 25% (LR=<0.3).

    [Diagnosis] Diagnostic Series-screen-shot-2016-12-19-at-10-12-00-pm-png

    In patients with cough and fever (EBM Box 3-1), the individual findings increasing the probability of pneumonia the most are egophony (LR=4.1), cachexia (LR=4), bronchial breath sounds (LR=3.3), and percussion dullness (LR =3). In contrast, no individual finding, when present or absent, significantly decrease the probability of pneumonia.

    EBM Box 3-1 also shows that a score of 4 or more points using the Heckerling diagnostic scheme significantly increases the probability of pneumonia (LR=8.2), whereas a score of 0 or 1 point significantly decrease it (LR=0.3).
    Last edited by admin; Mon 19th December '16 at 10:16pm.
    B.S. Pharm, West China School of Pharmacy, Class of 2007, Health System Pharmacist, RPh. Hematology, Infectious Disease. Chengdu, Sichuan, China.

    Blog: http://www.tomhsiung.com
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