Virtual patients for assessment of medical student ability to integrate clinical and laboratory data to develop differential diagnoses: comparison of results of exams with/without time constraints.

INTRODUCTION: We have evaluated medical student ability in a problem-based learning course using a virtual patient (VP)-based exam with variable parameters for assessment purposes. METHODS: A class of 155 second year medical students was assessed using a VP exam with unlimited access during a 1-week period; 2 years later, the identical exam was administered to 175 students with a 3-h time limit. RESULTS: Students taking the exam without time constraints utilized approximately twice as much time than students with the time limit. Without the pressure of a time-limit, students utilized half as many inquiries of the patient history, physical, and lab/imaging tests than were used by students having a time constraint, indicating that the time limited students used a "shotgun approach" to try to collect as many "required" inquiries as possible. Most students (91%) taking the untimed exam were able to correctly diagnose the exam case but only 31% of the time limited students correctly diagnosed the VP exam case, despite their higher number of inquiries. CONCLUSIONS: Our results demonstrate that an identical VP exam, administered with variables to compare untimed versus time-limited conditions, resulted in an unraveling of student's ability to integrate the data discovered during the process of progressive disclosure.