E2 ModerateModerate confidencePEM not requiredObservationalPeer-reviewedReviewed
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Mistaken Identity: Many Diagnoses are Frequently Misattributed to Lyme Disease.
Kobayashi, Takaaki, Higgins, Yvonne, Melia, Michael T et al. · The American journal of medicine · 2022 · DOI
Quick Summary
This study looked at over 1,000 patients who were referred to a hospital thinking they had Lyme disease, but actually didn't. The doctors found that 84% of these patients did not have Lyme disease at all. Instead, they had many other conditions causing their symptoms, including anxiety, depression, fibromyalgia, and chronic fatigue syndrome. This suggests that Lyme disease is being diagnosed too often when patients actually have other medical problems.
Why It Matters
For ME/CFS patients and researchers, this study is important because it demonstrates that ME/CFS (along with fibromyalgia and other post-infectious conditions) is frequently misidentified as Lyme disease in clinical practice. Understanding this diagnostic confusion helps explain why some ME/CFS patients may have received incorrect Lyme disease diagnoses and treatment, and highlights the need for improved diagnostic criteria and clinical awareness to distinguish between these overlapping symptom presentations.
Observed Findings
84% of 1,261 patients referred for Lyme disease had no evidence of active Borrelia burgdorferi infection.
Among 690 patients receiving alternative diagnoses, the most common were anxiety/depression (222 patients, 21%), fibromyalgia (120 patients, 11%), and ME/CFS (77 patients, 7%).
Median symptom duration was 796 days before diagnosis of alternative conditions.
59% of alternative diagnoses were newly discovered medical conditions, while 22% involved both new and pre-existing diagnoses.
Rare but serious diagnoses including multiple sclerosis (11), malignancy (8), Parkinson's disease (8), and ALS (4) were identified in patients initially suspected of Lyme disease.
Inferred Conclusions
Lyme disease is substantially overdiagnosed in patients with chronic symptoms, with 84% of referred patients lacking evidence of infection.
Patients with long-standing symptoms attributed to Lyme disease frequently have other medical conditions—particularly psychiatric, rheumatologic, and sleep disorders—that better explain their symptoms.
Clinical assessment for Lyme disease in chronic symptom presentations should include careful differential diagnosis to avoid missing treatable alternative conditions.
Remaining Questions
What clinical or demographic features distinguish patients who are correctly diagnosed with Lyme disease from those misdiagnosed, and how can providers improve diagnostic accuracy?
What This Study Does Not Prove
This study does not prove that Lyme disease and ME/CFS are mutually exclusive or that patients cannot have both conditions simultaneously. It also does not establish causation or mechanisms for why symptoms develop in these alternative diagnoses, only that they are more commonly present than Lyme disease in this referred population. The retrospective design limits causal inference and generalizability beyond the specific referral population studied.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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In patients with both Lyme disease exposure and ME/CFS or fibromyalgia, how do clinicians differentiate which condition is primarily driving symptoms?
What proportion of ME/CFS and fibromyalgia patients in primary care settings are incorrectly suspected or diagnosed as Lyme disease?
Do patients misdiagnosed with Lyme disease receive appropriate treatment for their actual underlying conditions, or does the incorrect label delay proper management?