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.

Penicillin Allergy and the Return of Pre-Pen

Penicillin allergy is by far the most commonly reported drug allergy.  However, the vast majority of patients reporting a penicillin allergy cannot remember ever having had a reaction.  Most were told at some point, usually by a parent or grandparent, that they had a penicillin allergy and some even tell me that it simply appeared in their medical chart for unclear reasons.  A study once showed that in 20% of hospital admissions, the patient reported an penicillin allergy, but when these people were tested, only 10% of those reporting an allergy were actually positive.  So, 90% of people who thought they had a penicillin allergy didn’t!

In penicillin allergy, people can react to different parts of the penicillin molecule. These parts were named major determinants and minor determinants based on the frequency of reactions to the different parts.  In the past, testing to the major determinant was done using a commercially available product called Pre-Pen.  Unfortunately, Pre-Pen was taken off the market several years ago, leaving allergists with little to test with.

It was announced today the Pre-Pen is coming back.  Production is to begin this month, in fact.  The product information sheet states that a negative skin test with Pre-Pen gives a less that 5% chance of reacting to therapeutic penicillin.

Our office will be stocking Pre-Pen and performing skin tests and oral challenges in appropriate patients.  If you would like to find out if you are really penicillin allergic, let us know.

Dr. O

Which flu vaccine is better: shot or mist?

Currently, influenza vaccines come in two flavors: nasal and injectable.  The nasal vaccine is a live, attenuated vaccine. This means that the virus, while still “alive”, has had its cellular machinery crippled so that it won’t cause a whole body infection.  The injectable vaccine is inactivated, or killed.  It is wholly incapable of causing infection.

The nasal vaccine is very popular in our office.  I guess people get enough shots around here, already.  Based on a study which came out today in the NEJM, I may be rethinking how I recommend different vaccines.

This study looked at healthy volunteers aged 18 to 49 years.  A very important point is that none of these individuals had a condition for which vaccine was explicitly recommended, i.e. healthcare workers, asthmatics, very old, very young, etc.  In this study population, the inactivated, injectable vaccine was clearly better at preventing influenza.  It wasn’t even close.   Rates of infection were 3.5% for the injectable vaccine, 7% for the nasal vaccine, and 11% for placebo.

This study is important in answering which vaccine young, healthy individuals should receive.  Results from other studies looking at outcomes in asthmatics have suggested that the nasal vaccine may actually be more effective at preventing influenza related exacerbations.  Clearly, this is an important question that needs more data to make a definitive answer.

I got my flu shot BTW

Dr. O

Asthma, Allergies, and Chlorine

Did you know that elite swimmers have a higher prevalence of asthma than other athletes?  Surprisingly, this fact was only confirmed in a study relatively recently.  Chlorine was an obvious candidate to explain this finding and over the last decade, evidence has been mounting to suggest that water chlorination does indeed lead to an increased risk of developing not only asthma, but allergies as well.

Initially, the problem was blamed on trichloramine, the gas that gives indoor pools their characteristic smell.  Once it was discovered that outdoor pool exposure was as bad as indoor pool exposure, then the focus shifted to chlorine products in the water or vapors present around the water surface.

A recent study from Belgium published in the journal Pediatrics looked at three groups of adolescents, two of which had utilized only chlorinated pools and one of which utilized a pool decontaminated by means of a copper/silver ionizer.  I read the study in detail and it is very complicated and has some potential holes.  Nevertheless, I think it does clearly demonstrate that kids who spend a large amount of time in a chlorinated pool are more likely to develop asthma and/or respiratory symptoms of cough and shortness of breath and are more likely to develop allergies.

Given that there are other means of decontaminating pools such as salt water or ionizers, regulatory bodies should reconsider the appropriateness of chlorine as the standard pool decontaminant.

Dr. O

Your Showerhead Might Kill You! Or, maybe not…..

Everybody Panic!

This is one of those stories that sounds scary as heck, but really isn’t telling us anything of consequence.  If you haven’t heard, some researchers cultured material from showerheads and found high levels of the atypical bacteria Mycobacterium avium intracellulare, or MAI, living there.  This isn’t very shocking as MAI is a water loving organism.

Anyway the important point here is that MAI is not very pathogenic.  Even if you’re exposed to it, the likelihood of it causing clinical disease is exceedingly low.  If you have a very weakened immune system, like late stage HIV or post-chemotherapy, you might take notice, but for the vast majority of us this is  a non-issue.

Dr. O