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What is the incidence of PAN?
Reecently someone posted the figure of 350 for the total number of PAN cases in the world. As we all said, this cannot possibly be true, because there are nearly 350 people in the PAN group, and we've only contacted a small fraction of the vasculitis patients in the world.
Today I asked one of my students who is particularly proficient at library research to see what she could find on the topic. My thanks to her for finding the following studies.
The most recent, and the best of the studies, comes from Dr. Loic Guillevin and his co-workers in France. This study was just published in the February 15, 2004 issue of the journal Arthritis and Rheumatism. The title of the study is "Prevalences of Polyarteritis Nodosa, Microscopic Polyangiitis, Wegener's Granulomatosis, and Churg-Strauss Syndrome in a French Urban Multiethnic Population in 2000: A Capture-Recapture Estimate".
The bottom line of this very elegant study is that the prevalence of PAN is 30.7 per 1,000,000 adults, for MPA it is 23.7, for WG it is 23.7, and for CSS it is 10.7. Now, if we assume that those rates hold true throughout the world, and the population of the USA is 290.3 million, then we can predict that there are about 8,900 PAN patients in the USA alone. In Peter's Australia, we can project over 600 PAN patients.
In this study, the overall prevalence of the 4 types of vasculitis was 90.3 per 1,000,000. This would translate into over 26,000 cases of vasculitis in the USA and nearly 1800 in Australia.ased on this study, and a couple of other (older) studies, I think it's safe to say that the estimate of 350 PAN patients worldwide is an extreme underestimation.
Regards,
Eric
My father read somewhere that PAN is caused by pesticides. Any comments?
Jim has already characterized this as hogwash, and I agree, except that I would never abuse a hog like that!
There is *NO* evidence that pesticides cause PAN. If your doctors have some information to the contrary, I would like to see it.
I am a researcher who is looking at the things that can cause vasculitis. We have examined a number of chemicals, including pesticides, and have not been able to find *ANY* link between a givengroup of chemicals and vasculitis. That is a scientific fact, and you can tell your father that it comes from a research doctor who has spent nearly 30 years studying autoimmune diseases.
Now for a personal opinion: The doctors who told your father that there was a link between pesticides and PAN are worse than simply ignorant. Wherever they got that idea, they should check and confirm it before telling a patient that something he did was the cause of his disease. I have no problem telling a smoker that smoking caused his lung cancer, because there are hundreds of studies to support the association, and anyone who has read a newspaper since 1964 has seen articles that report on the link.
Were the doctors who told your father that pesticides are associated with PAN real MD's, or were they some kind of "alternative" quacks. Often there are chiropractors, naturopaths, homeopaths, or other quacks who want to blame the patient for the disease, and they come up with some outlandish explanation like this. If the doctors were actually MD's they are not very smart, they are clearly not compassionate, nor are they informed about vasculitis.
Please tell your father to ignore this hogwash. If he would like to talk to me about research on the causes of vasculitis, I will be happy to call him.
Aren't there studies being done to see if there is a link between silica and PAN?
Yes, this is one of the strongest links we have to an occupational exposure and vasculitis. It is important to note that the vasculitis patients in these studies are silica miners who had daily chronic exposure to the silica dust. I've also seen one patient who was an insulation installer. He blew glass-wool insulation into walls and attics of buildings, and he refused to wear a protective mask. He was also a tobacco smoker. He developed WG. I'm not aware of any studies that show a link between casual exposure to silica and vasculitis.
Some of these studies were reported at the Vaculitis Conference in Cleveland, and you have posted the link to those abstracts in the past.Best regards,
Eric
Do we know what causes PAN?
Our current hypothesis of the origin of autoimmune disease is:
Hi Dr. Eric,
I have some questions related to my sister. She just told me yesterday that she has been having a 'rash' on her shins/calves. It's not really a rash, as it is under the skin. Knowing about my diagnosis with PAN, she went to a dermotologist. He told her she has pigmented purpura. The info I have found on the web is quite vague. Can you tell me about this condition please. Do you think it could be something else - should she have a skin biopsy to rule out any more serious diseases? Should she see a rheumatologist?
We just find this so odd, that this has surfaced for her, after my being afflicted with PAN. Do these kinds of vascular problems run in families? Any information or advice would be greatly appeciated!!
Pigmented purpura is a rare skin disorder. The cause is unknown, but it is probably not autoimmune. In pigmented purpura, the very small capillaries in the skin become more permeable and begin to "leak" red blood cells into the surrounding tissue spaces. Initially this may look like red inflammation, later like blue bruises, and even later as an orange-red pigmentation of the skin.This is probably not related to PAN or other forms of vasculitis, but it is so rare that no one has done any real studies on the associations. There are clear differences in the appearance of the blood vessels and surrounding tissues when we look at them through the microscope. The orange pigmentation seen in pigmented purpura is due to deposition of of an iron-containing compound called hemosiderin.
Your sister should have a skin biopsy to make a definite diagnosis. The dermatologist is the specialist of choice for this condition, but it should be someone who has seen and treated this condition before.
Autoimmune diseases tend to run in families, because there are genetic links for many autoimmune diseases. However, NO genes have been identified for either PAN or pigmented purpura, so it is impossible to say for sure if there is a genetic link.
The biopsy is the definitive diagnostic test for PAN. Some Rheumatologists may make a diagnosis of MPA based on physical findings and a positive P-ANCA, but I think most would want a biopsy to confirm that. As you said, the ANCA test is not widely available. Additionally, the results may vary from one lab to another. I have done a lot of work with the ANCA test, and I have written a newsletter for lab personnel regarding the proper testing protocols. If you'd like a copy, let me know. It's not available in an electronic format, so I'll need to send it by snail mail.
Tonya, Your last sentence is the $64,000 question, and I'm sure that many here would agree. Vasculitis has so many wild and weird presentations that it is difficult to say that ANYTHING can be ruled out.Superficial Perivascular Dermatitis has also been called Idiopathic Petechial Dermatitis, Idiopathic Telangectasia, and (my favourite) Funny Splotches on The Skin. Idiopathic means, "we don't know what causes it", so basically, you have Funny Splotches of Unknown Origin on the Skin.
I would follow your Dermatologist's recommendations. Stay out of the sun, use sunblock (year around), wrap yourself in aluminum foil when you go outside (OK, I made that one up...).Have you been tested for SS-A antibodies? Very often these antibodies can be associated with a photosensitive skin rash.Let me know if I can help in any way.
Why (at least by current stats) do women have a greater tendency toward AI diseases? Or is this info even correct?
However, it isn't all hormones, because the vast majority of women never develop AI diseases. This is why we think that there are multiple
factors - genetic, hormonal, environmental, stress - that are the "cause" of AI diseases.
Antidepressant drugs can be a tremendous help for patients with autoimmune diseases. If your rheumy/internist isn't comfortable with using antidepressants, ask for a psychiatric consult. I have see some wonderful recoveries form the symptoms of both depression and the autoimmune disease in patients who take antidepressants.
One caution: antidepressant drugs can be very powerful, and they should only be taken with the supervision of a psychiatrist (MD), who should monitor the patient carefully, especially in the first few days of antidepressant therapy. I wouldn't trust a psychologist or other alternative health care worker to monitor the treatment of depression.
