How are Allergies Like My Dog?

I have a freakishly large Golden Retriever named Ozzy.  He performs some important household chores like waking me up at 6am every day, pre-rinsing the dishes in the dishwasher and destroying any rogue tennis balls that might be laying around the house.  He’s two, now, which for a Golden means that he’s still really energetic. If I don’t find time to let him do what he was bred to do, run around like crazy chasing stuff then bringing it back to me, he will start to act out.

The immune system of an allergic person is sort of like Ozzy.  It’s designed to to a specific job and do it well and when it isn’t presented with the chance to do that job, it will find something else to do.  The part of the immune system that is responsible for allergies is really designed to fight off parasites.  We don’t have a big parasite problem is the Western world anymore, but we do have a huge, and growing, allergy problem.  One theory as to why allergies are becoming more common states that since the parasite arm of the immune system is not required to do its job much anymore, it goes looking for something else to do.  What it finds, instead of parasites, is pollens, dust mites, peanuts, and the rest of the common allergens.  It incorrectly senses that these things are potentially harmful and it sets up a reaction to get rid of them.  That reaction causes the symptoms experienced by allergy sufferers.

Some people have taken this theory as far as infecting themselves with hookworms to see if it improves their allergies and there are anecdotal reports of this process working.  Usually these reports come directly from the people selling the worms, however.  There is serious research into this treatment going on at present and the results should interesting.  For now, though, we’ll stick to antihistamines, nasal steroid sprays, and immunotherapy.

Whooping Cough: Don’t Call it a Comeback….

California is in the midst of its worst whooping cough outbreak in 50 years.  Before a vaccine was available, whooping cough killed around 5000 Americans a year, mostly infants.  Add to that the substantial morbidity it caused and whooping cough was a major public health issue.  When the  whooping cough vaccine became available in the 1940’s, the number of cases declined precipitously.  Since the 1980’s, however, the number of whooping cough cases has been on the rise.

Whooping cough is not a trivial disease. It is caused by a bacteria called Bordetella pertussis that infects the lungs.  Apart from the small mortality risk, the two things that make whooping cough so bad are the intensity of the disease and the duration.  The “whoop” in whooping cough refers to the characteristic noise made when its sufferers cough.  It has also been referred to as a bark, honk, or seal-like noise.  The cough is so severe that it is not uncommon for sufferers to cough until they vomit or crack ribs.  Whooping cough is also known as the “100-day cough”.  After the acute illness subsides, the cough can linger for months.

Back to California.  A recent NY Times article illustrates some of the reasons for the return of this old foe.  It highlights Marin County, a wealthy bay area enclave that is home to 0.5% of the states’ population, but 15% of the states’ whooping cough cases.  In Marin county, 13% of infants and children remain unvaccinated, the 7th highest rate in the state.  It is this lack of vaccination that allows diseases like whooping cough to gain a foothold in a community.

I’ve said it before in this blog, but it bears repeating:  vaccines may be the most important public health advance in the history of mankind and that is not hyperbole.  In order for them to be maximally effective, to achieve herd immunity, they need to be used universally.  Some vaccines are better than others, but they are all better than nothing.  The risks of vaccination are negligible, especially when compared with the risk of not vaccinating.

Finally, when considering not vaccinating your child, remember that you  are not only putting your child at risk, but you are also increasing the risk for every other individual in the community.

More news on the diagnosis, or misdiagnosis, of peanut allergy.

Hey! We’re back.

I took a little hiatus from the blog.  We had a really busy tree season, I moved into a new house, and we had a little rain in the Nashville area.  My thoughts have been elsewhere.

For my re-entry post I thought I’d touch on a recent article looking at the mess that is peanut allergy diagnosis.  I’ve written about this before and related the uncertainty inherent in interpreting food allergy tests- particularly food allergy blood tests.  In simplest terms, food allergy testing is very good at ruling OUT allergies, but when the test comes back positive then in doesn’t necessarily indicate a true allergy.  How do we handle this?

It may be helpful at this point to draw a distinction between sensitization and allergy.  When an allergy blood test comes back positive, that shows sensitization: the body’s immune system has come into contact with that substance and has responded to it by making a specific allergy antibody, sIgE in the medical shorthand.  The problem is that sensitization to a substance does not mean a person is allergic to that substance.  An allergic person will have a reaction when exposed to that substance, but many people who are sensitized are not allergic.

Are you more confused?  Lets look at the study to clarify.

Researchers in the U.K. and Sweden tested 933 kids and found that around 12% were sensitized to peanut (had a positive test), but only about 2.5% had true peanut allergy (reacted when they ate peanuts).  That means that 75-80% of kids with a positive peanut test weren’t peanut allergic in this study.  Imagine how many families are needlessly stressing over peanut allergy!

The study used oral peanut challenges-having the kids eat peanuts- as a gold standard for diagnosing peanut allergy.  Most community allergists don’t do this because they lack the resources to properly carry out the test.  Many families are wary of doing this because of the risk of severe reactions.  These researchers used a new test called component resolved diagnostics (CRD)to see if they could better identify who was truly allergic and who was simply sensitized.  CRD works like a usual allergy blood test except that it measures sensitization to very specific parts of the peanut protein.  The researchers found kids who were sensitized to one particular peanut component, called Ara h 2 if you need to know, were much more likely to react to peanuts.

This is only one study and I’m not sure yet how CRD will fit into clinical practice just yet.  However, I think it is very promising and I’m hopeful that it will give us a useful tool to better diagnose and manage peanut allergy.

Dr. O

Update on the FDA and Long-Acting Beta-Agonists

I’ve posted before on the issue of LABAs and safety.  LABAs are medications that help keep the airways open fro 12 or so hours.  Both Advair and Symbicort have a LABA in them.  Concerns have been raised about the safety of LABAs, primarily based on flawed data from poorly done trials.  Nevertheless, the FDA has responded again to this issue, despite the fact that there is no new information on LABAs and safety.  The FDA is simply issuing another proclamation based on the same data that the last proclamation was based on.  Curious.  If the data is the same, I don’t see why the recommendations should be any different.

In fact, most of the recent recommendation from the FDA does not differ substantially from the previous one.  First, they reiterate that LABAs should not be used alone without using an inhaled corticosteroid at the same time.  (Both Advair and Symbicort contain an inhaled steroid in addition to a LABA.)  Second, they reiterate that LABAs should only be used in patients for whom other medications, usually simple inhaled steroids, have been ineffective.  Neither of these points is new or controversial.

They now recommend that children and adolescents using combination inhaled steroid/LABA therapy only be given devices which contain both.  That is they should not have a steroid inhaler and a LABA inhaler, but should use either Advair or Symbicort.  I don’t know for sure, but I’d guess that 99% of children or adolescents using combination therapy are already using a combination inhaler.

The point that is causing some controversy is this, and I’ll quote for accuracy, “ LABAs should be used for the shortest duration of time required to achieve control of asthma symptoms and discontinued, if possible, once asthma control is achieved. Patients should then be maintained on an asthma controller medication.” I think that this is a bad recommendation, and apparently so do some other asthma physicians. After yesterday’s press conference, some members of the American Thoracic Society asked for clarification on this statement.  The FDA’s response was much more tempered, “ The FDA’s intention is to encourage patients and providers to seek to reduce LABA use as much as possible if symptom control can be maintained without it. However, the FDA recognizes in some cases, discontinuation of LABA use, or even reduction of LABA use, may not be possible.”

I agree with the overriding principle of utilizing the minimum amount of medication needed to maintain adequate control, but the FDA’s recommendation does not follow this principle.  Rather it seems to say, “Wait til your patient gets sick, then add on more medication.  When they’re better stop til they get sick again and restart.”  Lather. Rinse. Repeat.  I would suggest that maintaining good control, preventing exacerbations, is a much better idea and if that means keeping the LABAs on board, then so be it.

I’m sure this won’t be the last of this issue.

Dr. O

Does Your Child Really Have Food Allergies?

Here’s a common scenario in my office:  A parent has taken their child to the primary care physician’s office to talk about possible allergies.  The physician sends off a “screening allergy panel” blood test which contains a few common airborne allergens like pollens, dust mites and cat dander.  The panel also contains tests for common foods like peanuts, milk, eggs, and soy.  A few of the food tests come back as positive and the parents are told their child has food allergies and needs to see an allergist.  The parents have heard horror stories about food allergy reactions and are scared stiff that their child may have one, even though he has always tolerated these foods in the past.  What do you do next?

Melinda Beck at the Wall Street Journal recently wrote an excellent article on this conundrum.  You can find it here. I highly recommend it.  It reiterates what allergists have been telling patients all along:  blood tests can be poor predictors of true food allergy.  A test is just a number, a patient is a person.  There’s a big difference.  In some studies, over 50% of kids tolerated foods they had been told to avoid.

These problems could largely be solved with a few simple steps.  First, and this is directed to the primary care physicians, STOP ORDERING FOOD ALLERGY TESTS INDISCRIMINATELY.  Sorry to all-caps and bold that, but I can’t stress this enough.  If the history does not suggest food allergy then there is no indication for ordering food allergy tests.  Simple rhinitis, sinusitis, otitis, and asthma are not food allergy related and foods have no place on a screening panel of allergy tests when evaluating these disorders.  To quote from Ms. Beck’s article, ““Are these blood tests being overused? Possibly. Misinterpreted? Absolutely,” says Robert Wood, director of Pediatric Allergy and Immunology at Johns Hopkins Hospital…”

Second, and this is directed at the labs running the tests: Stop putting foods in your screening allergy panels and stop marketing such panels to primary care docs.  This practice wastes money on needless tests and causes confusion and anxiety for countless families.  In short it is irresponsible.

Third, if you have questions about allergies, see you local board certified allergist.  In most cases a simple history will be enough to tell true food allergy from false positive blood tests.  Allergists have years of specialized training and experience in the proper selection and interpretation of allergy tests and the management and treatment of allergy problems.  They are best suited to help you solve these issues.

Contact Dermatitis & The True Test Recall

Contact dermatitis is the rash that occurs when your skin comes into contact with something to which it is sensitive.  (Sounds kind of obvious, huh?)  Unlike hives which can come and go rapidly, a contact dermatitis rash typically takes a few days to fully blossom and can take a week or two to resolve.  The classic contact dermatitis is poison ivy and many people are also sensitive to nickel from jewelry or the back of the snap on your jeans.  Contact dermatitis is a distinctly different type of reaction from a true allergic reaction like wheezing, sneezing, or hives.  There are no measures to desensitize people who have contact dermatitis, so identification and avoidance of triggers is the key.

The good news is there is a commercially available product that tests for the vast majority of substances that cause contact dermatitis in the general population.  The method is called patch testing and the product is the True Test.  Basically, these are strips of tape that are impregnated with the common contact dermatitis causing substances. They have gigantic names like p-tert-Butylphenol Formaldehyde Resin and Mercaptobenzothiazole. You wear the strips of tape on your back for a few days and peel them off to reveal, hopefully, what is causing the problem.

The bad news is that the True Test folks just issued a recall for their testing products.  Apparently an important component had been left out of the test panel.  They tell us it will be March before we get new patch tests, so until then we’ll have to make do with the 5 we have left that were not affected by the recall.

Good Luck True Test Guys!

Dr. O

Gas Appliances and Asthma

I saw an old patient of mine yesterday who has pretty significant asthma.  She had been really well controlled for the last couple of years until a month or so ago when her symptom frequency started to increase.  She was having more trouble exercising and had used her nebulizer a few times as well.  The only thing she noted that was different was that some family had come for an extended visit.  She told me her grandsons had been playing around with the gas fireplace and she had been cooking more with her gas range and gas oven.  We checked her lung function and it had fallen by about 40% since her last visit!

This illustrates an important and often under-recognized point about asthma and indoor air quality.  Though we think often of outdoor air quality, checking for levels of ozone, sulfur dioxide, and diesel exhaust particles, indoor pollutants can lead to respiratory problems as well.  Indoor flames from gas fireplaces, gas ranges and ovens, wood burning stoves and unvented kerosene or gas space heaters emit nitrogen dioxide, a respiratory irritant.  Nitrogen dioxide has been clearly shown to worsen symptoms in asthmatics and COPD patients.  If you have fuel burning appliances in your home, the EPA recommends these steps to reduce harmful indoor pollutants:

• Properly ventilate a room where a fuel-burning appliance is used and use appliances that vent to the outside whenever possible.
• Do not idle the car inside your garage.
• Have the entire heating system — including furnace, flues and chimneys — professionally inspected and cleaned annually.
• Always open the flue on your fireplace before building a fire to ensure that smoke escapes through the chimney.
• Make sure the doors are tight fitting on your wood-burning stove and follow the manufacturer’s directions for starting, stoking and putting out the fire.
• Follow the manufacturer’s directions for proper fuel use on unvented kerosene or gas space heaters and keep the heater properly adjusted. Open a window slightly or use an exhaust fan in the room while using the heater.
• Install and use an exhaust fan over a gas stove and vent it outdoors.

Eczema Treatment Tips

I was down in Miami last week for the ACAAI meeting and spent a day at the literature review course.  There’s always an allergic skin disease segment, and the lecturer this year, dermatologist Dr. Vincent Beltrani, was full of good information and  provided us with some practical tips for eczema care.  I’ll highlight some below.

1. You must prevent scratching!  Try applying cool compresses to any itch.
2. Overheating and sweating triggers itch.  Stay cool.
3. Prevent dry skin.  Sponge bathe or take short tepid baths.
4. Use a ceramide cleanser (Aveeno Advanced Care), avoid soap which will dry the skin
5. Pat dry, do not rub dry.  Rubbing causes more itching
6. Lubricate, lubricate, lubricate, especially right after bathing.  He recommended EpiCream, Aveeno Advanced Care or CeraVe
7. Dust mite proof your bed, if you are dust mite allergic

If these aren’t working, see you doctor for additional treatment strategies

Dr. O

Long Term Inhaled Steroids vs Intermittent Oral Steroids

Inhaled corticosteroids (ICS) have been the mainstay of asthma treatment for over 30 years.  The steroid molecules have improved considerably over time, with greater topical potency and less systemic side effects.  During that time, numerous studies have shown that ICS are effective at reducing symptoms, exacerbations, hospitalizations, and death due to asthma.  Likewise, there have been numerous studies examining the side effects of these medications which have shown that in low to medium doses, there are few if any systemic complications.  In the highest doses, there may be a slight increase in cataracts and loss of calcium from the bone.  But, and this is a very important point, these risks have to be weighed against the risks of the alternative: more symptoms, more exacerbations and more oral steroid use.

A common concern voiced by patients and parents is, “I don’t like taking medications” or “I don’t want my child to be on daily medications”.  It’s right to be thoughtfully critical of regular medication use, but, by the same token, if regular medications are helpful and are the better alternative, then they are a good choice.  In order to explain why regular ICS are a good choice, I’ve got to do a little math.  Let’s say you were just using a rescue inhaler for asthma control and that during the last year you only required one course of oral steroids, prednisone.  A usual prednisone “burst” is 40mg a day for 5 days for a total of 200mg or 200,000mcg.  By way of comparison, each dose of Advair 100/50 contains 100mcg of fluticasone, the steroid.  If you took Advair 100/50 twice a day, the usual dose, it would take you 1000 days of regular use to equal the amount of steroids in one burst of prednisone on a mcg-per-mcg basis.

But wait, there’s more.  When you swallow a predinisone pill, 100% of the drug makes it into your system.  Doctors call this bioavailability.  In contrast, the bioavailability of inhaled steroids, especially the newer molecules is very low, from 1-6%.  Why is this? When you use an ICS, you swallow a significant amount of the drug.  When the swallowed portion is absorbed in the stomach, it travels directly to the liver where it is broken down and inactivated.  This is called first pass metabolism.  A part of the inhaled portion of the drug  can still make it into the blood stream.  This part is not immediately inactivated by the liver and, therefore, is the portion which can lead to systemic side effects.  So, back to the math: if only 1% of the inhaled steroid dose in Advair is bioavailable, then you multiply 1000 days by 100 to get 100,000 days of regular use to equal one burst of prednisone on a bioavailable mcg-per-mcg basis.

To be completely honest, the newer inhaled steroids are more potent than prednisone on a mcg-per-mcg basis which means the 100,000 day number is inflated.  Also, the amount of steroid that is absorbed and the subsequent systemic side effects vary based on delivery device, inhaler technique, and timing of administration.  Nevertheless, the underlying point holds true:  one round of oral steroids is worth a whole lot of inhaled steroids.  Given this and the quality of life improvements afforded by regular inhaled steroids, in all but the mildest asthmatics the tradeoff is a no-brainer.

Another Hit Against SLIT?

Sublingual Immunotherapy, SLIT or “allergy drops”, continues to be a hot topic in the allergy community.  There continue to be questions about its effectiveness and its exact role in allergy treatment.  A couple of recent articles have added to the debate.

The first article looked at SLIT using one allergen vs. SLIT with multiple allergens.  This has always been a big question  regarding SLIT use in the U.S., since most U.S. allergy sufferers are allergic to multiple different allergens.  In this trial, they took people with grass pollen allergy and put them on SLIT containing either  just grass pollen or grass pollen and several other allergens.  At the end of the trial, neither group showed any difference in symptom scores or medication use, though the grass pollen alone group did better in some secondary measures.  This trial reiterates the difficulties U.S. researchers have had replicating the overwhelmingly positive results of the southern European researchers.  It calls into question whether SLIT will be widely adopted in the U.S..  If multi-allergen SLIT is ineffective, then it will not be appropriate for the majority of U.S. immunotherapy candidates.

The second paper reviewed the several meta-analyses published regarding SLIT.  A meta-analysis takes numerous studies and pools their information to try and achieve higher statistical certainty regarding the subject.  MAs can be helpful, but they are not the ultimate answer some claim them to be.  Often the studies they use are very different in terms of patient selection, interventions, methodology, and endpoints.  They also suffer from the GIGO problem:  garbage in, garbage out.  In other words, pooling a bunch of poorly done studies does not make for one good study.

In any event, this review of 5 MAs looking at SLIT found numerous inconsistencies among the MAs.  That is, when different MAs used data from the same trial, they reported different outcomes from the trial.  This is a big red flag and signals that the MA authors were either altering the data to fit their predetermined conclusions or were being inexcusably sloppy.  The reviewers also noted probable “publication bias”, where positive studies get published and included in MAs, but negative trials get ignored and never published.  Despite all this, the reviewers conclusion was that there was not sufficient evidence to recommend SLIT at this time.

We at  the AAAMT have about 20 patients currently on SLIT, versus over 1000 on traditional allergy shots.  I’ve been brutally honest with SLIT patients regarding my healthy skepticism for the long-term prognosis of SLIT.  In my opinion, the jury is still out on SLIT and I will continue to recommend it only in rare circumstances.