Downsides of IgeneX Testing for Lyme Disease
The primary downside of IgeneX testing for Lyme disease is the high risk of false-positive results that can lead to misdiagnosis, unnecessary treatment, and potential harm to patients due to the use of unvalidated testing methods and non-standard interpretation criteria. 1
Problems with Alternative Testing Methods
Lack of FDA Validation
- IgeneX uses laboratory-developed tests that are not subject to FDA regulations and may not be clinically validated 1
- These tests often use non-standard interpretation criteria for Western immunoblots or fail to perform the recommended first-tier EIA 1
- A recent evaluation of alternative laboratories reported an alarming false-positive rate of 58% for samples from healthy control patients 1
Misleading Claims
- Alternative laboratories like IgeneX often appeal to patients by claiming to specialize in tick-borne diseases and asserting superior sensitivity compared to standard two-tiered testing 1
- These claims are not supported by rigorous scientific evidence and can lead patients to pursue unnecessary treatments
Clinical Implications of False-Positive Results
Misdiagnosis and Inappropriate Treatment
- False-positive results can lead to patient confusion, misdiagnosis, and inappropriate antibiotic treatment 1, 2
- Patients may receive unnecessary long-term antibiotic therapy, which carries risks including adverse drug reactions, antibiotic resistance, and Clostridioides difficile infection
Delayed Diagnosis of True Underlying Conditions
- When patients are misdiagnosed with Lyme disease based on false-positive test results, investigation into the true cause of their symptoms may be delayed or abandoned
- This can lead to worsened morbidity and mortality from the actual underlying condition
Pretest Probability and Test Interpretation
Importance of Pretest Probability
- The value of any Lyme disease test depends heavily on pretest probability based on exposure history and clinical presentation 1, 2
- In low-incidence regions or for patients without travel to endemic areas, positive serologic results provide little diagnostic value 1
- Even clinical signs considered consistent with Lyme disease have poor predictive value in low-incidence regions 1
Recommended Testing Approach
- The CDC and Infectious Diseases Society of America recommend using only FDA-cleared two-tiered testing for Lyme disease diagnosis 1, 2
- This consists of an initial EIA/ELISA followed by Western immunoblot confirmation if the first test is positive or equivocal 2
- Standard two-tiered testing has excellent specificity (>95%) when properly performed and interpreted 2
Financial Considerations
- IgeneX testing is typically more expensive than standard two-tiered testing
- These tests are often not covered by insurance, resulting in significant out-of-pocket expenses for patients
- The cost-benefit ratio is poor given the high rate of false-positive results
Appropriate Testing Scenarios
When Testing is Appropriate
- Testing should be limited to patients with objective signs of Lyme disease and appropriate exposure history 1, 2
- In endemic areas, erythema migrans can be diagnosed clinically without laboratory testing 2
- For suspected late manifestations like Lyme arthritis, standard two-tiered testing has high sensitivity (70-100%) 2
When Testing Should Be Avoided
- Testing should be minimized in patients with non-specific symptoms and low pretest probability 1, 3
- Routine testing is not recommended for patients with typical neurological conditions like ALS, MS, or Parkinson's disease 2
Conclusion
If Lyme disease testing is needed, clinicians should only use FDA-cleared tests with validated interpretation criteria 1. The high rate of false positives from alternative laboratories like IgeneX can lead to misdiagnosis, unnecessary treatment, and delayed identification of the true cause of a patient's symptoms.