Purpose: This assignment aims to reinforce the analytic basis for diagnosis. It should improve your practical understanding of the concepts of pre-test probability, likelihood ratios, post-test probability, and thresholds to test and treat.

Task: You will analyze the differential diagnosis for a patient presenting with a specific complaint. You should pick a patient presenting with a complaint that has a differential diagnosis with at least two legitimate possibilities.

If possible, we encourage you to select diseases or symptoms that are reviewed in JAMA’s Rational Clinical Examination (RCE) Series.  A list of the diseases covered in this series are found at the end of this document.

In brief, you will estimate the probability of disease for each of the possibilities on the differential diagnosis after you’ve obtained the history and physical examination during the patient’s initial visit to clinic. You will estimate the effect of a test on these probabilities and assign specific thresholds to test and treat. A video explaining how to do this assessment can also be found on Canvas.

Instructions:

1. Use the ICR Bayesian Analysis Assignment Template document (available on Canvas) to complete your assignment. A sample of what the completed assignment should look like is also on Canvas.
2. Enter in to the Table the disease you are considering as a possible explanation for your patient’s presentation.
3. Next enter a threshold to test and a threshold to test for this disease in your patient. Remember that the thresholds are unique to each patient.  Please refer to the syllabus and the video lecture on Thresholds if you need more information on how to set the thresholds.
   1. For the Threshold to Test, consider:
      1. Disease mortality/morbidity if untreated
      2. Risk/invasiveness of the test
   2. For the Threshold to Treat, consider
      1. Disease mortality/morbidity if untreated
      2. Risk/invasiveness of the treatment
4. Pick a test (physical finding, lab or imaging study) that might help you sort out whether your patient has the disease in question or not. Your patient may not have actually had this test done.  Find the positive and negative likelihood ratios (LR) for the test and enter in the table.  Also enter the source you used for the likelihood ratios
   1. A few good resources include:
      1. JAMA’s Rational Clinical Exam series
      2. Dynamed
      3. The book “Symptom to Diagnosis”
5. Estimate the pre-test probability of the disease in your patient: Read carefully about the prevalence/incidence of the diseases on your differential diagnosis in the outpatient setting, as well as their symptoms and signs using Dynamed, UpToDate, and/or the RCE series. Use other resources if those are unhelpful (e.g., Google Scholar or PubMed searches).  Remember pre-test probability is a typically determined by combining knowledge of the prevalence/incidence of a disease with the symptoms and signs found on history and physical examination.  Sometimes you can find prediction rules that allow you to do this rapidly (e.g., Diamond-Forrester table for stable angina, Wells’ score for DVT and PE).  Spend no more than one hour performing this research.  If you are having trouble with your search, feel free to contact the research librarians or the course directors for help.  Enter the pre-test probability in the Table
6. Enter the likelihood ratios (from Step 4 above) for the test you chose
7. Calculate the post-test probability of the disease you are considering for both a positive and negative test. You can use either the Bayes nomogram or on online calculator (http://araw.mede.uic.edu/cgi-bin/testcalc.pl)
8. Enter the Thresholds to Test and Thresholds to Treat you determined earlier (from Step 3 above)
9. Interpretation: Discuss how the pre- and post-test probabilities compare to the thresholds and how the test might be useful in evaluating your patient for the specific disease you are considering. State whether the test is useful or not and whether you would do the test.  For example:  “The post-test probability  after a positive test exceeds my pre-determined threshold to treat and thus it is a useful test as it prompts me to treat the patient if positive.  If the test is negative, however, the post-test probability remains above my threshold to test and thus it would not be as useful in this scenario”.

RESOURCES

Evidence-based Physical Examination.  McGee, S. 4th edition; Elsevier; (2017) (book)

From Symptom to Diagnosis. An Evidence-based Guide. Stern S, Cifu A. Altkorn A. 3rd edition; McGraw-Hill Education; (2014). (book)

Rational Clinical Examination: Evidence-base Clinical Diagnosis. Simel D, Rennie D. 1st edition; McGraw-Hill Education; (2008). (book, also individual papers as below)

Common

• Does this patient have strep throat? JAMA 2000 Dec 13;284(22):2912-8.
• Does this patient have sinusitis? JAMA 1993 Sep 8;270(10):1242-6.
• Does this woman have an acute uncomplicated urinary tract infection? JAMA 2002 May 22-29;287(20):2701-10.
• Does this patient have influenza? JAMA 2005 Jan 28;293(8):987-997.
• Does this patient have community-acquired pneumonia? JAMA 1997 Nov 5;278(17):1440-5.
• Does this patient with shoulder pain have rotator cuff disease? JAMA 2013 Aug 28; 310(8):837-47
• What can the history and physical examination tell us about low back pain? JAMA 1992 Aug 12;268(6):760-5.
• Will this patient develop disabling persistent low back pain? JAMA 2010; 303: 1295-1302.
• Does this older adult with lower extremity pain have the clinical syndrome of lumbar spinal stenosis? JAMA 2010; 304 (23) 2628-2636.

• Does This Patient With Palpitations Have a Cardiac Arrhythmia? JAMA. 2009;302(19):2135-2143.
• Does this patient have dementia? JAMA 2007 Jun 6; 297(21):2391-2404.
• Does this dizzy patient have a serious form of vertigo? JAMA 1994 Feb 2;271(5):385-8.
• Does this patient with headache have a migraine or need neuroimaging? JAMA 2006 Sep 13;296 1274-1283.
• Does this patient have temporal arteritis? JAMA 2002 Jan 2;287(1):92-101.
• What type of urinary incontinence does this woman have? JAMA 2008 Mar 26;299(12)1446-56.
• Evaluation of vaginal complaints. JAMA 2004 Mar 17;291(11):1368-79.
• Is this woman perimenopausal? JAMA 2003 Feb 12;289(17):895-902.
• Does this patient have an alcohol problem? JAMA 1994 Dec 14;272(22):1782-7.
• Is this patient clinically depressed? JAMA 2002 Mar 6;287(9):1160-70.
• Does this patient have generalized anxiety or panic disorder? JAMA, July 2, 2014;312(1):78-84.
• Does this man with lower urinary tract symptoms have bladder outlet obstruction?JAMA 2014;312(5):535-542.

Less common

• Does this patient have early HIV infection? JAMA 2014 July 16; 312(3):278-285
• Does this patient have erythema migrans? JAMA 2007 June 20;297(23)2617-2627.
• Does this patient with diabetes have osteomyelitis of the lower extremity? JAMA 2008 Feb 20;299(7):806-813.
• Does this coughing adolescent or adult patient have pertussis? JAMA 2010 Aug 25;304(8):890-896.
• Does this adult patient have septic arthritis? JAMA 2007 Apr 4;297(13):1478-1488.
• Does this patient have Parkinson’s disease? JAMA 2003 Jan 15;289(3):347-53.
• Does this patient have myasthenia gravis? JAMA. 2005;293:1906-1914.
• Is this patient having a stroke? JAMA 2005 May ; (14):1114-20.
• Does this adult patient have septic arthritis? JAMA 2007 Apr 4;297(13):1478-1488.

BY ORGAN SYSTEM

Cardiology

• Does this dyspneic patient in the ED have CHF? JAMA. 2005;294:1944-1956.
• Can the clinical examination diagnose left-sided heart failure in adults? JAMA 1997 Jun 4;277(21):1712-1719.
• Does this patient have abnormal central venous pressure? JAMA 1996 Feb 28;275(8):630-4.
• Does this patient have an abnormal systolic murmur? JAMA 1997 Feb 19;277(7):564-571.
• Does this patient have an acute thoracic aortic dissection? JAMA 2002 May 1;287(17):2262-2272.
• Is this patient having a myocardial infarction? JAMA 1998 Oct 14;280(14):1256-63.
• Does the clinical examination predict lower extremity peripheral arterial disease? JAMA 2006 Feb 1;295(5):536-636.

Endocrinology

• Does this patient with diabetes have large-fiber peripheral neuropathy? JAMA 2010; 303: 1526-1532.
• Does this woman have osteoporosis? JAMA 2004 Dec 15;292(23):2890-2900.

Gastroenterology

• Does this patient have a severe upper gastrointestinal bleed? JAMA 2012;307(10): 1072-1079.
• Does this patient have acute cholecystitis? JAMA 2003 Jan 1;289(1):80-6.
• Does this patient have appendicitis? JAMA 1996 Nov 20;276(19):1589-94.
• Can the clinical history distinguish between organic and functional dyspepsia? JAMA 2006 Apr 5;295(13):1566-1576.
• Will the history and physical examination help establish that irritable bowel syndrome is causing this patient’s lower gastrointestinal tract symptoms? JAMA 2008 Oct 15;300(15):1793-1805.

Gynecology

• What type of urinary incontinence does this woman have? JAMA 2008 Mar 26;299(12)1446-56.
• Evaluation of vaginal complaints. JAMA 2004 Mar 17;291(11):1368-79.
• Is this woman perimenopausal? JAMA 2003 Feb 12;289(17):895-902.

Hematology-Oncology

• Does this patient have breast cancer? JAMA 1999 Oct 6;282(13):1270-80.
• Does this patient have deep vein thrombosis? JAMA 2006 Jan 11;295(2):199-207.

Infectious Diseases

• Does this patient have early HIV infection? JAMA 2014 July 16; 312(3):278-285
• Does this patient have erythema migrans? JAMA 2007 June 20;297(23)2617-2627.
• Does this patient have influenza? JAMA 2005 Jan 28;293(8):987-997.
• Does this patient with diabetes have osteomyelitis of the lower extremity? JAMA 2008 Feb 20;299(7):806-813.
• Does this patient have community acquired pneumonia? JAMA 1997 Nov 5;278(17):1440-5.
• Does this coughing adolescent or adult patient have pertussis? JAMA 2010 Aug 25;304(8):890-896.
• Does this adult patient have septic arthritis? JAMA 2007 Apr 4;297(13):1478-1488.
• Does this patient have sinusitis? JAMA 1993 Sep 8;270(10):1242-6.
• Does this patient have strep throat? JAMA 2000 Dec 13;284(22):2912-8.
• Does this woman have an acute uncomplicated urinary tract infection? JAMA 2002 May 22-29;287(20):2701-10.
• Does this adult patient have acute meningitis? JAMA 1999 Jul 14;282(2):175-81.

Neurology

• Does this patient have Parkinson’s disease? JAMA 2003 Jan 15;289(3):347-53.
• Does this patient have dementia? JAMA 2007 Jun 6; 297(21):2391-2404.
• Does this patient with headache have a migraine or need neuroimaging? JAMA 2006 Sep 13;296 1274-1283.
• Will this patient develop disabling persistent low back pain? JAMA 2010; 303: 1295-1302.
• Does this patient have myasthenia gravis? JAMA. 2005;293:1906-1914.
• Is this patient having a stroke? JAMA 2005 May ; (14):1114-20.
• Does this dizzy patient have a serious form of vertigo? JAMA 1994 Feb 2;271(5):385-8.

Orthopedics

• Does this patient with shoulder pain have rotator cuff disease? JAMA 2013 Aug 28; 310(8):837-47
• What can the history and physical examination tell us about low back pain? JAMA 1992 Aug 12;268(6):760-5.
• Does this older adult with lower extremity pain have the clinical syndrome of lumbar spinal stenosis? JAMA 2010; 304 (23) 2628-2636.

Psychiatry

• Does this patient have an alcohol problem? JAMA 1994 Dec 14;272(22):1782-7.
• Is this patient clinically depressed? JAMA 2002 Mar 6;287(9):1160-70.
• Does this patient have delirium? JAMA, August 18, 2010—Vol 304, No. 7: 779-786.
• Does this patient have generalized anxiety or panic disorder? JAMA, July 2, 2014;312(1):78-84.

Pulmonary

• Does this patient have pulmonary embolism? JAMA 2003 Dec 3;290(21):2849-58.

Rheumatology

• What can the history and physical examination tell us about low back pain? JAMA 1992 Aug 12;268(6):760-5.
• Does this adult patient have septic arthritis? JAMA 2007 Apr 4;297(13):1478-1488.
• Does this patient have temporal arteritis? JAMA 2002 Jan 2;287(1):92-101.

Urology

• Does this man with lower urinary tract symptoms have bladder outlet obstruction? JAMA 2014;312(5):535-542.