ObjeCtiveTo determine the diagnostic and triage accuracy of online symptom checkers (tools that use computer algorithms to help patients with self diagnosis or self triage). DesignAudit study.setting Publicly available, free symptom checkers.PartiCiPants 23 symptom checkers that were in English and provided advice across a range of conditions. 45 standardized patient vignettes were compiled and equally divided into three categories of triage urgency: emergent care required (for example, pulmonary embolism), non-emergent care reasonable (for example, otitis media), and self care reasonable (for example, viral upper respiratory tract infection). Main OutCOMe MeasuresFor symptom checkers that provided a diagnosis, our main outcomes were whether the symptom checker listed the correct diagnosis first or within the first 20 potential diagnoses (n=770 standardized patient evaluations). For symptom checkers that provided a triage recommendation, our main outcomes were whether the symptom checker correctly recommended emergent care, non-emergent care, or self care (n=532 standardized patient evaluations). resultsThe 23 symptom checkers provided the correct diagnosis first in 34% (95% confidence interval 31% to 37%) of standardized patient evaluations, listed the correct diagnosis within the top 20 diagnoses given in 58% (55% to 62%) of standardized patient evaluations, and provided the appropriate triage advice in 57% (52% to 61%) of standardized patient evaluations. Triage performance varied by urgency of condition, with appropriate triage advice provided in 80% (95% confidence interval 75% to 86%) of emergent cases, 55% (47% to 63%) of non-emergent cases, and 33% (26% to 40%) of self care cases (P<0.001). Performance on appropriate triage advice across the 23 individual symptom checkers ranged from 33% (95% confidence interval 19% to 48%) to 78% (64% to 91%) of standardized patient evaluations.COnClusiOns Symptom checkers had deficits in both triage and diagnosis. Triage advice from symptom checkers is generally risk averse, encouraging users to seek care for conditions where self care is reasonable.

The Institute of Medicine recently highlighted that physician diagnostic error is common and information technology may be part of the solution. 1 Given advancements in computer science, computers may be able to independently make accurate clinical diagnoses. 2 While studies have compared computer vs physician performance for reading electrocardiograms, 3 the diagnostic accuracy of computers vs physicians remains unknown. To fill this gap in knowledge, we compared the diagnostic accuracy of physicians with computer algorithms called symptom checkers. Symptom checkers are websites and apps that help patients with self-diagnosis. After answering a series of questions, the user is given a list of rank-ordered potential diagnoses generated by a computer algorithm. Previously, we evaluated the diagnostic accuracy of 23 symptom checkers using 45 clinical vignettes. 4 The vignettes included the patient's medical history and had no physical examination or test findings. In this study we compared the diagnostic performance of physicians with symptom checkers for those same vignettes using a unique online platform called Human Dx. Methods | Human Dx is a web-and app-based platform on which physicians generate differential diagnoses for clinical vignettes. Since 2015, Human Dx has been used by over 2700 physicians and trainees from 40 countries who have addressed over 100 000 vignettes.

Borrelia burgdorferi does not signify the presence of active infection or bacteremia that merits prolonged antibiotic treatment. To this point, Marques et al 2 tested a cohort of patients with treated Lyme disease and posttreatment Lyme disease syndrome (PLTDS) for the presence of viable B burgdorferi. Using a xenodiagnostic technique wherein laboratory-raisedIxodes scapularis ticks fed on patients and subsequently attempted to infect immunodeficient mice, both ticks and mice were tested for the presence of B burgdorferi by PCR and culture. Despite detecting B burgdorferi DNA by PCR amplification in a single patient with PLTDS on 2 separate occasions, the investigators were unable to culture B burgdorferi. This supports current evidence that the association between microbiological data-especially PCR-and symptoms in patients with reported persistent Lyme disease remains unproven. 3 The more important point regards treatment. Even in cases meeting clinical criteria for PLTDS, an uncommon constellation of systemic symptoms following antibiotic treatment for Lyme disease, multiple trials have demonstrated the absence of significant or sustained benefit with prolonged antibiotic courses. For example, compared with placebo, a 90-day course of ceftriaxone and doxycycline did not improve perceived symptoms in either seronegative or seropositive patients with persistent symptoms. 4 Interestingly, no B burgdorferi DNA was detected by PCR in any patient following enrollment or treatment. Fallon et al 5 demonstrated modest but nonsustained improvement in cognition following 10 weeks of ceftriaxone compared with placebo in patients with previously treated Lyme disease and memory impairment. In both trials, antibiotic therapy was associated with an increase in adverse events, including catheterassociated venous thromboembolism and drug reactions, as in the case of the patient in our Teachable Moment. 6 Thus, despite the suggestion by Dr Lee of objective evidence regarding the existence of chronic Lyme disease, the current recommendations and our conclusion remain that prolonged courses of antibiotics for this indication pose real harm without proven benefit.

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