Diagnostic Reasoning, also known as DxR, is patient-simulation software that analyzes a user's ability to diagnose a problem correctly and to recommend appropriate therapy. The software is intended for use by all levels of medical students, but it also has potential benefits for faculty. Developed by the DxR Development Group, Inc., DxR can be used to evaluate an entire group of student scores and show areas in which students have excelled or done poorly.
In a typical case, the user signs on to the program and chooses a patient. The user is presented with the patient's chief complaint and medical history. The user chooses questions to ask the patient from a list of 250 interview questions. Before proceeding to the physical exam, the user is prompted to make hypotheses as to the possible cause of the problem and to rank them in order of probability. Next, the user performs a physical exam on the patient. The user is presented with photographs of the patient including close-ups of specific body regions. Buttons and pull-down menus represent the 375 available physical exam procedures. In most cases, the user clicks a button to select an exam tool, such as an ophthalmoscope, hammer, or sphygmomanometer. The cursor turns into the exam tool and then the user moves the tool over the patient's body and clicks the mouse to see the findings. Findings are presented as text, pictures, sound, or video—whichever format is appropriate to the exam. At any point, the user can revise the list of hypotheses. After the physical exam, the user moves on to laboratory tests and chooses from a list of 450 possible tests. Test results are also given in the appropriate format. The user makes a final diagnosis, indicating level of confidence in the diagnosis, and then prescribes treatment. After treatment has been prescribed, the case is complete and the user receives a final score and a performance evaluation.
Although the process may sound somewhat complex, a user can flow through it smoothly after some basic instruction. One of the most interesting features of DxR is that users can relate one or more of their hypotheses to specific interview questions, exams, or labs. This feature has the potential to help faculty understand why a student selected a particular lab or exam. The evaluation section is particularly nice for the user because it gives instant feedback. Users are evaluated in seven different areas including how well they consider other options, how thorough they are, and how much attention they pay to efficiency and lab costs. For example, in evaluating questioning skills, a user may be told that out of 250 interview questions, eight are crucial to ask and the user has asked six of those questions.
The entire DxR package consists of over sixty patient cases—each based on a real patient. Cases can be purchased individually, but there are savings when multiple cases are purchased. The entire DxR package including all the cases can be purchased for $42,000. This price includes a two-day, onsite workshop on how to set up and use the program. Any new cases added after the initial purchase are available at a 70% discount. The cases come ready to go but faculty may also customize them. During the entire patient encounter, there is a consultant feature, which can be turned on or off by faculty, to help students interpret exam findings and lab results.
At times, there are definite advantages to using a program like DxR. The most obvious is that students can practice the patient encounter and develop their diagnostic skills on a variety of patients, albeit virtual patients. Furthermore, they have the flexibility to examine and diagnose virtual patients at whatever times work best in their schedules. In addition, students can be exposed to a wider variety of cases than may normally be encountered during a limited period of time, such as a semester. Finally, DxR can save money if it allows a school to reduce its use of professional (i.e., paid) patients.
DxR can have also advantages over case presentations led by faculty. In case presentations, students are “given” most of the information and must interpret it. With DxR, students are challenged to ask the right questions, perform the right exams, and order the appropriate lab tests. Compared to some other computer-based instructional programs, DxR is more free-form; it does not guide the student through the patient encounter. Rather than being prompted by the computer, the student must decide how to proceed.
There are some areas in which DxR could be improved. The screen layout is very busy with many buttons and pull-down menus. This layout can be confusing, distracting, and even overwhelming. It takes time to learn how to navigate, especially the physical exam. If the cursor is not placed exactly on the correct body part, an instrument will not work. For example, positioning the sphygmomanometer on the patient's arm and not the elbow is difficult. Some of the sounds need to be improved so that abnormalities are more recognizable. Although the evaluation section is definitely beneficial, it could be improved by adding more detailed explanations as to why a particular question, lab, or exam is considered crucial. Because faculty can edit cases, the explanations can be improved if faculty have the time to work with DxR.
In general, this reviewer found DxR to be a very good program and had no problems installing a sample case. According to Novartis, there would be a Web version available in fall 1999. The catalog already lists a broad range of cases covering primary care problems such as headache, chest pain, and dizziness, and new cases are being added frequently. Faculty can also create their own cases, and the DxR Development Group will provide a considerable amount of assistance. As with other computer-based instructional programs, the best way to use DxR is by incorporating it into a class or clerkship rather than using it as a stand-alone product. The full benefits of DxR can be realized when faculty customize cases to meet specific needs and review student scores and performance.