Thursday, June 11, 2009

The Lyme Disease Controversy

The CDC clinical criteria for Lyme Disease which exist for the purpose of monitoring the rate of Lyme disease nationally are quite narrowly defined in order to ensure a high degree of specificity in the diagnosis. These criteria are mainly useful for the early stages and rheumatological presentations of Lyme Disease,such as when a patient appears with an erythema migrans rash, arthritis, a Bell's palsy, or early central neurologic Lyme disease (meningitis or encephalitis). The CDC criteria are not very helpful for helping the clinician to detect late stage neurologic Lyme Disease. For example, the most common manifestation of late neurologic Lyme Disease is cognitive dysfunction (often referred to as "encephalopathy"). A patient who presents with new onset encephalopathy and a positive blood test for Lyme Disease would not be considered by the CDC to be a case of Lyme disease. Although the CDC recognizes that Lyme encephalopathy exists, encephalopathy is not part of the "surveillance case definition". Hence, physicians who rely on the narrow surveillance case criteria of the CDC for clinical diagnosis will fail to diagnose some patients who in fact do have Lyme disease; in these cases, the patient's treatment will either not occur or be delayed. Such delay in treatment may result in an acute treatable illness becoming a chronic less responsive one.

Other physicians who use a broader more inclusive set of clinical criteria for the diagnosis of Lyme disease will make the diagnosis of Lyme Disease and initiate treatment. The latter group of doctors, by treating some patients for "probable Lyme Disease", will make use of antibiotic responsiveness to confirm their diagnostic impression. These physicians, by erring on the side of not letting a patient with probable Lyme Disease go untreated, will help many patients who otherwise would not get treatment; undoubtedly, however, because of the inclusiveness of their diagnostic approach, these physicians will also treat some patients with antibiotics who do not have Lyme Disease. These physicians would argue that the serious consequences for physical, cognitive, and functional disability associated with chronic Lyme Disease outweigh the risks of antibiotic therapy.

Both sets of doctors are practicing medicine in a reasonable fashion based on the application of certain diagnostic principles, although the therapeutic approaches differ considerably stemming from the narrow vs broad criteria for diagnosis. This is the essence of the medical controversy surrounding chronic Lyme disease. Until medical doctors have a test that definitelyy identifies the presence or absence of infection (and such a test does not yet exist), the controversy about the diagnosis and treatment of chronic Lyme Disease will continue. (posted by my friend K.N.)

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