http://relative-risk.blogspot.com/2012/ ... ients.html
23 AUGUST 2012
Angry chronic patients
Lancet Infectious Diseases, Sep 2012.
Lack of knowledge can anger patients with chronic diseases
As seen in the correspondence related to Lyme disease, people with diseases of unknown cause want explanations at all costs. I have encountered this feeling since the beginning of my career. At the end of the 1970s a French diagnostic test for rickettsioses was introduced that was far from specific and gave false-positive results in 70% of cases, including patients with multiple sclerosis, schizophrenia, chronic arthritis, and myocardial infarction. The advent of immunofluorescence substantially decreased the number of false-positives, but throughout the 1990s I still saw patients with multiple sclerosis claiming to have a rickettsiosis and wanting to be treated with doxycycline. One laboratory in South Africa still uses the same diagnostic technique and sporadically I see or hear from patients asking me whether this serological examination should be used to try to explain the cause of chronic fatigue syndrome or chronic arthralgia.
The problem of Lyme disease has replaced rickettsioses in France and worldwide, and despite the addition of western blot to the diagnostic protocol, diagnosis of the disease is far from perfect. In my own laboratory, 90% of positive ELISA tests are not confirmed with western blot. Additionally, the antibodies detected in western blot, although specific, can result from an old contact; in some populations up to 70% of completely asymptomatic people have antibodies against Borrelia burgdorferi. Thus the positive predictive value of a serological test for B burgdorferi for an atypical disease is close to zero. Similarly, Bartonella spp infection is increasingly associated with a range of disorders, including Lyme disease, despite absence of evidence for a causal link and problematic diagnosis.
Some patients with diseases of unknown cause try to pinpoint an event associated with their illness: vaccination or bites by insects or ticks are identified most often. Indeed, a bite or vaccination is the only important event reported in the month preceding the onset of their symptoms. Of course causality cannot be deduced only from the timing of the event, especially when frequent diseases follow common risks. The difficulty of establishing causal links is the root of debate.
The inability to specify a cause of some chronic disorders can lead to antagonism between various parties. Often, conflict arises between patients and patients’ associations, doctors who do not accept that we do not know the causes of some diseases and so over-interpret diagnostic tests, and those defending a scientifically established position of knowledge. We must all remember that apparent causal links can have serious consequences, as did the erroneous links made between autism after measles, mumps, and rubella vaccination in the UK and multiple sclerosis after vaccination against hepatitis B in France, which led to a pronounced decrease in vaccination coverage.
On the whole, the medical community has not sufficiently explained to the public or medical students that, even nowadays when so much information seems to be available (especially on the internet), that much remains unknown about many diseases. Ongoing discoveries will hopefully provide scientific explanations, but currently these gaps in our knowledge are unbearable for many patients leading some physicians to overuse and over-interpret diagnostic tests.
Unité de Recherche sur les Maladies Infectieuses et Tropicales
Emergentes (URMITE), CNRS UMR 6236, Faculté de Médecine,
Aix-Marseille University, Marseille 13005, France