A while back I mentioned two web based differential diagnosis resources, Isabel and Dxplain. I have access to Dxplain through Merck Medicus and signed up for a free trial of Isabel, so I decided to plug a challenging case into both programs and compare their performance.
The CPC in the February 9 2006 NEJM featured an uncommon presentation of giant cell arteritis dominated by chest pain and respiratory complaints. Myalgias were also present, mistakenly attributed to statin drugs. The following findings were entered into both programs: chest wall pain; ear pain; shoulder pain; myalgias; hoarseness; exertional dyspnea; fatigue; sore throat. Age (elderly) and gender (female) were entered. Although both programs encourage entry of laboratory results you can enter as much or as little data as you wish, and I decided to see how the programs did with only the initial presenting clinical manifestations. I opted not to enter the patient’s sedimentation rate of 90. That would have made it too easy.
Isabel missed the boat entirely with a long list of diagnoses across multiple specialties, with the only rheumatologic diagnosis offered being relapsing polychondritis. Dxplain fared better by coming up with polymyalgia rheumatica. Neither program diagnosed giant cell arteritis or temporal arteritis. So, Dxplain wins the first round. As time permits before my free Isabel trial expires I’ll try more cases and report back.