Q J Med 2003; 96: 763-769
© 2003 Association of Physicians
Probabilistic reasoning and clinical decision-making: do doctors overestimate diagnostic probabilities?
From the 1Faculty of Medicine, The Hebrew University of Jerusalem, 2Heart Institute, Hadassah University Hospital, 3School of Public Health, The Hebrew University of Jerusalem, and the Hadassah University Hospital, Jerusalem, Israel
Received 20 February 2003 and in revised form 5 June 2003
Background: The ‘threshold approach’ is based on a physician’s assessment of the likelihood of a disease expressed as a probability. The use of Bayes’ theorem to calculate disease probability in patients with and without a particular characteristic, may be hampered by the presence of subadditivity (i.e. the sum of probabilities concerning a single case scenario exceeding 100%).
Aim: To assess the presence of subadditivity in physicians’ estimations of probabilities and the degree of concordance among doctors in their probability assessments.
Design: Prospective questionnaire.
Methods: Residents and trained physicians in Family Medicine, Internal Medicine and Cardiology (n = 84) were asked to estimate the probability of each component of the differential diagnosis in a case scenario describing a patient with chest pain.
Results: Subadditivity was exhibited in 65% of the participants. The total sum of probabilities given by each participant ranged from 44% to 290% (mean 137%). There was wide variability in the assignment of probabilities for each diagnostic possibility (SD 16–21%).
Discussion: The finding of substantial subadditivity, coupled with the marked discordance in probability estimates, questions the applicability of the threshold approach. Physicians need guidance, explicit tools and formal training in probability estimation to optimize the use of this approach in clinical practice.
Address correspondence to Dr O. Paltiel, School of Public Health, Hadassah University Hospital, Kiryat Hadassah POB 12000, Jerusalem 91120, Israel. e-mail: ora{at}vms.huji.ac.il
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  M. T. Bianchi, B. M. Alexander, and S. S. Cash Incorporating Uncertainty Into Medical Decision Making: An Approach to Unexpected Test Results Med Decis Making, January 1, 2009; 29(1): 116 - 124. [Abstract] [PDF]
|
|
|
|
 |
|
 J. Coste, P. Jourdain, and J. Pouchot A Gray Zone Assigned to Inconclusive Results of Quantitative Diagnostic Tests: Application to the Use of Brain Natriuretic Peptide for Diagnosis of Heart Failure in Acute Dyspneic Patients Clin. Chem., December 1, 2006; 52(12): 2229 - 2235. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. T Bianchi and B. M Alexander Evidence based diagnosis: does the language reflect the theory? BMJ, August 26, 2006; 333(7565): 442 - 445. [Full Text] [PDF]
|
|