Resources medical students use to derive a differential diagnosis.

Background: Deriving an appropriate differential diagnosis is a key clinical competency, but there is little data available on how medical students learn this skill. Software resources designed to complement clinical reasoning might be asset in helping them in this task.

Aims: The goals of this study were to identify the resources third year medical students use to solve a challenging diagnostic case, and specifically to evaluate the usefulness of Isabel, a second-generation electronic diagnosis support system.

Methods: Third year medical students (n = 117) were presented a challenging case and asked to identify and prioritize their top 3 diagnoses, report the time devoted to the exercise, and list the resources they used and their relative usefulness. Students were randomized to receive (or not) free access, instruction, and encouragement to use to a web-based decision support system (Isabel).

Results: Students who identified the correct diagnosis as their first choice spent significantly more time on the case than did the other students (3.75 +/- 0.28 hours vs 2.88 +/- 0.15 hours, p < 0.05). Students used electronic resources extensively, in particular Google. Students who self-reported use of Isabel had greater success identifying the correct diagnosis (24/33 = 73% for users vs 45/84 = 53% for non-users) a difference of borderline statistical significance.

Conclusions: These findings indicate that medical trainees use a wide range of electronic decision support products to solve challenging cases. Medical education needs to adapt to this reality, and address the need to teach future clinicians how to use these tools to advantage.