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    1 Comment for this article
    Brilliant study, shocking results
    Jason Maude | Founder, Isabel Healthcare
    This study on diagnosis accuracy and confidence is brilliant and the authors are to be congratulated. However, the results that show an accuracy rate of 55% for the easy cases and just 6% for the hard cases are truly shocking and the authors’ statement that  "overall diagnostic accuracy was rather low- 31% across the 4 cases” must be the understatement of the year. Having been used in other studies, the cases used are generally acknowledged to be difficult but if the physicians taking part in the study thought they were difficult then why didn’t the confidence rates fall from the 60-70% level to 10-20%? There is nothing in wrong in admitting very little confidence in your judgement on a particular case (with the implication that you will find out more) but there is something wrong in giving a false sense of confidence. Accuracy of diagnosis appears to have been barely affected after the history and physical stages with labs and imaging, begging the question what value is really provided by the expensive and invasive testing?Lack of time did not seem to be an issue in the low levels of accuracy. It seems that the high levels of confidence meant that the physicians did not request additional resources. Rather than the term 'over confidence' a more apt explanation may be the "illusion of knowledge". The over confidence results from the illusion of knowledge.One of the solutions suggested by the authors is  "engaging patients in creative ways" one of which could be actively encouraging patients to use sophisticated symptom checkers before the consultation so that they can contribute more productively to the diagnostic process.
    CONFLICT OF INTEREST: Founder of Isabel Healthcare, a company which produces diagnosis decision making aids.
    Original Investigation
    November 25, 2013

    Physicians’ Diagnostic Accuracy, Confidence, and Resource Requests: A Vignette Study

    Author Affiliations
    • 1Houston Veterans Affairs Health Services Research and Development Center of Excellence and the Section of Health Services Research, Houston, Texas
    • 2Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas
    • 3Baylor College of Medicine, Houston, Texas
    JAMA Intern Med. 2013;173(21):1952-1958. doi:10.1001/jamainternmed.2013.10081

    Importance  Little is known about the relationship between physicians’ diagnostic accuracy and their confidence in that accuracy.

    Objective  To evaluate how physicians’ diagnostic calibration, defined as the relationship between diagnostic accuracy and confidence in that accuracy, changes with evolution of the diagnostic process and with increasing diagnostic difficulty of clinical case vignettes.

    Design, Setting, and Participants  We recruited general internists from an online physician community and asked them to diagnose 4 previously validated case vignettes of variable difficulty (2 easier; 2 more difficult). Cases were presented in a web-based format and divided into 4 sequential phases simulating diagnosis evolution: history, physical examination, general diagnostic testing data, and definitive diagnostic testing. After each phase, physicians recorded 1 to 3 differential diagnoses and corresponding judgments of confidence. Before being presented with definitive diagnostic data, physicians were asked to identify additional resources they would require to diagnose each case (ie, additional tests, second opinions, curbside consultations, referrals, and reference materials).

    Main Outcomes and Measures  Diagnostic accuracy (scored as 0 or 1), confidence in diagnostic accuracy (on a scale of 0-10), diagnostic calibration, and whether additional resources were requested (no or yes).

    Results  A total of 118 physicians with broad geographical representation within the United States correctly diagnosed 55.3% of easier and 5.8% of more difficult cases (P < .001). Despite a large difference in diagnostic accuracy between easier and more difficult cases, the difference in confidence was relatively small (7.2 vs 6.4 out of 10, for easier and more difficult cases, respectively) (P < .001) and likely clinically insignificant. Overall, diagnostic calibration was worse for more difficult cases (P < .001) and characterized by overconfidence in accuracy. Higher confidence was related to decreased requests for additional diagnostic tests (P = .01); higher case difficulty was related to more requests for additional reference materials (P = .01).

    Conclusions and Relevance  Our study suggests that physicians’ level of confidence may be relatively insensitive to both diagnostic accuracy and case difficulty. This mismatch might prevent physicians from reexamining difficult cases where their diagnosis may be incorrect.