Food allergy “testing” is usually a bad idea

Posted March 23, 2015 by Dr. Roy
Categories: Nutrition, Pediatric Insider information

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The Pediatric Insider

© 2015 Roy Benaroch, MD

People like tests. You get numbers, and maybe a printout, and there’s science and blood and things just feels more… serious, when testing is done. You can picture Marcus Welby  (or perhaps a more modern physician), looking solemn, declaring “We’d better run some tests.”

Are medical tests magical and mysterious, and can they unlock the secrets of life? Usually, no. And among the worst and most misunderstood tests we do are food allergy tests.

A few recent studies illustrate this well. A review of about 800 patients referred to an allergy clinic found that almost 90% of children who had been told to avoid foods based on allergy testing could in fact eat them safely. The study, bluntly titled “Food allergen panel testing often results in misdiagnosis of food allergy” also found that the positive predictive value of food allergy blood tests—the chance that a positive test accurately predicted real allergy—was 2.2%. That much, much worse than the odds if you flipped a coin, and much, much worse than your odds of winning at a casino. If someone told you that a positive test was only correct 2% of the time, would you even do the test?

What about the other way of food allergy testing, with skin scratch or prick tests? A recent study about peanut allergy made big news when it turned out to show that early peanut exposure can prevent allergy. (This isn’t new news, by the way—I’ve written about that before. But I get fewer readers than the New England Journal of Medicine.) But hidden in the methods and statistics of that paper was another gem. The authors tested all of the enrolled babies for peanut allergy, at the beginning of the study. And most of the babies who “tested positive”, whether or not they then ate peanuts, did not turn out to be allergic. A true statement from the data from that study would be: If your baby tests positive for peanut allergy, your child is probably not allergic to peanuts.

Read that sentence again. Kind of makes your brain hurt, doesn’t it?

It is true that positive-tested kids were more likely than negative tested kids to be allergic—among the group with more allergies later (those who avoided peanuts), 35% of those who had positive tests developed allergy, versus 14% who had tested negative. But still, in either case, most of the kids who tested positive did not turn out to be allergic, whatever they ate or did.

The fundamental problem, I think, is that doctors either don’t understand or can’t seem to explain the difference between sensitization and allergy. None of these tests can actually test for allergy—they test for sensitization, which is different. We gloss over that distinction, and end up giving out bad advice. People should not be told to avoid food based on the results of allergy testing alone.

Bottom line: if you child eats a food without having a reaction, he or she is not allergic, and you should not do any testing for that food as a potential allergen. You should never do broad panels of “allergy tests”—they’re much more likely to mislead and confuse than to give useful information. Any food allergy testing that is done should only look at foods that seem to have caused reactions in the past, and even then any positive testing should be confirmed by what’s called an “open challenge.” Under safe conditions, usually under an allergists’ care, give the child some of the food to eat to see what happens. That’s the only real way to “test” for allergy.

Football helmets protect skulls. They don’t protect brains.

Posted March 16, 2015 by Dr. Roy
Categories: Medical problems

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The Pediatric Insider

© 2015 Roy Benaroch, MD

A few weeks ago, I wrote about concussions—mild brain injuries caused by trauma. There’s increasing concern that repeated concussions—that is, repeated brain injuries—aren’t good. They can lead to depression, intellectual decline, movement disorders, and other kinds of symptoms that you’d expect from someone whose brain has been injured multiple times.

One tack that athletics departments are taking is to invest in more-expensive helmets. The idea has some appeal—wrap your head in something protective, and then you can bash it into things safely. But there’s a fundamental misunderstanding here. Helmets, the best helmets, can do a really good job at protecting your child’s skull from damage. But no helmet in the world has ever been shown to provide any protection for your child’s brain.

Think about it. The helmet protects the outside of your head, the hair, the skin, the eyes the cheekbones, all of those. People wearing helmets do not get lacerations of the scalp, and they don’t fracture their skulls, because the helmet protects these body parts from damage. But the brain, that is a very different story.

Your brain floats on the inside of your skull, enveloped in fluid. It gets injured not by directly smashing into someone else’s head, or into the ground, or into a windshield. The brain doesn’t strike your steering wheel and it doesn’t get hit by a hockey puck or a boxer’s gloved fist. What strikes your brain, and what causes the damage, is the inside of your own skull.

Picture this: you’re in a speeding car. You, your head, your skull, and your brain are all traveling 60 miles an hour when you swerve off the road into a concrete pole. Very quickly, you and your head stop moving—BAM, you’ve decelerated from 60 mph to zero in just a fraction of a second. If you’re lucky, your head is protected by snapping forward not into the windshield or your steering wheel, but into a relatively-soft air bag. Air bags do a great job to protect skulls and heads. But what happens to your brain? As smart as it might be, brains follow the laws of physics, too. It was just moving at 60 mph, and the thing carrying it, the skull, just stopped. The brain then slams into the front of the skull, from the inside, at 60 mph.

There is no airbag in there to protect the brain. In a car accident, the brain just slams into the inside of the skull. And in a football injury, the same thing happens—the helmet protects the scalp and the head, sure, but the brain still slams into the skull from the inside. Unless they figure out a way to implant a little helmet inside the head, between the brain and the skull, there’s nothing in there protecting the brain.

It’s worse, by the way. The really bad concussions—the most serious brain injuries—come from the brain slamming sideways into the side of the skull, or from rotational forces that shear the cortex, the top thinking part of the brain, away from the base (think of slapping a top from the side and watching it spin. Whee! Brain!) In any scenario, the physics are the same—forces act on the skull to change its motion, and the brain slams into the skull from the inside.

Good sports equipment is still essential for athletes, and I don’t mean to minimize what a good helmet can do. I don’t want poked out eyeballs or broken jaws or caved in skulls, either. But I’d also like to see a more-honest discussion of brain injury in sports, and what we can and cannot do to prevent and mitigate the effects of these injuries. We’re not getting honest info from the helmet manufacturers, that’s for sure.

Help fight childhood cancer, and help me get bald!

Posted March 10, 2015 by Dr. Roy
Categories: Medical problems

Heya fellow lovers of science and children! In a few days I’ll be getting my head shaved to help raise money to fight childhood cancer through St. Baldrick’s. It’s a great charity, and it’s a fun way to let the kids know we love them and would do anything to help.

As ya’ll know, I don’t take any advertisers, and I have no financial relationships or anything to disclose about drugs, medical products, or any of that lucrative endorsement stuff that could rake in the dough. I write and manage this blog just to ham it up, have a good time, and hopefully spread some solid info about children’s health. I don’t even accept donations to the blog (there is a “donate” link over there, but it’s just for show. As far as I know no one has ever clicked it.)

If you’ve ever felt that this blog is a useful resource and wanted to thank me by tossing over a few dollars, why not click this link and donate to St. Baldricks? You’ll help children with cancer, and you’ll get a glowy feeling inside. I’ll end up with less hair. It’s a win-win!

Get ready for spring! Allergy therapy update, 2015

Posted March 9, 2015 by Dr. Roy
Categories: Medical problems

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The Pediatric Insider

© 2015 Roy Benaroch, MD

In last year’s Pulitzer Prize winning* post, I reviewed the medications available for treating the symptoms of spring allergies—antihistamines, nasal sprays, prescription and non-prescription goodness. There’s some new information and changes this year, so it’s time for an update!

First, a study just published provides more reassurance about the use of topical nasal spray steroids and growth. About 220 kids aged 3-9 were randomized to receive placebo nasal spray or intranasal triamcinolone (sold OTC as “Nasacort”), and their growth was followed before, during, and after treatment. Growth when the medication started was very slightly slower (by about an eighth of an inch a year), but that difference was quickly erased by catch-up growth after the medication was stopped. In typical practice, these medicines aren’t used year-round anyway. Bottom line: if there is any effect on growth, it’s insignificant, and it’s temporary.

We’ve also got the first FDA-approved sublingual allergy immunotherapy tablet to come to market. Sold as “Grastek”, taken regularly this can help children and adults overcome allergy to one specific plant, Timothy Grass. Downside: it takes a long time to “kick in”, and it only protects against this one specific pollen—when usually, people with polen allergies are allergic to multiple things. So I’m not sure just how useful this is. Still, it’s an interesting foot-in-the-door for home immunotherapy without the shots. I’m sure we’ll be seeing more of this kind of thing.

Here’s the rundown on all of the other medications, updated for 2015:

Antihistamines are still very effective for sneezing, drippy noses, and itchy noses and eyes. The old standard is Benadryl (diphenhydramine), which works well—but it’s sedating and only lasts six hours. Most people use a more-modern, less-sedating antihistamine like Zyrtec (cetirizine), Claritin (loratidine), or Allergra (fexofenidine.) All of these are OTC and have cheapo generics. They work taken as-needed or daily. There are still a few prescription antihistamines, but they have no advantage over these OTC products. Antihistamines don’t work at all to relieve congested or stuffy noses—for those symptoms, a nasal steroid spray is far superior.

Decongestants work, too, but only for a few days—they will lose their punch quickly if taken regularly. Still, for use here and there on the worst days, they can help. The best of the bunch is old-fashioned pseudoephedrine (often sold as generics or brand-name Sudafed), available OTC but hidden behind the counter. Don’t buy the OTC stuff on the shelf (phenylephrine), which isn’t absorbed well. Ask the pharmacist to give you the good stuff he’s got in back.

Nasal cromolyn sodium (OTC Nasalcrom) works some, though not as strongly as prescription nasal sprays. Still, it’s safe and worth a try if you’d rather avoid a prescription.

Nasal oxymetazolone (brands like Afrin) are best avoided. Sure, they work—they actually work great—but after just a few days your nose will become addicted, and you’ll need more frequent squirts to get through the day. Just say no. The prescription nasal sprays, ironically, are much safer than OTC Afrin.

Nasal Steroid Sprays include OTCs Nasacort and now OTC Flonase. There are also many prescription products, like generic fluticasone, Rhinocort, Nasonex, Nasarel, Veramyst, and others. All of these are essentially the same (though some are scented, some are not; some use larger volumes of spray.) All of them work really well, especially for congestion or stuffiness (which antihistamines do not treat.) They can be used as needed, but work even better if used regularly every single day for allergy season.

Antihistamine nose sprays are topical versions of long-acting antihisamines, best for sniffling and sneezing and itching. They’re all prescription-only (though they’re super-safe). They’re marketed as either the Astelin/Astepro twins (Astepro came out later, when Astelin became available as a generic; it lasts longer) or Patanase.

Bonus! Eye allergy medications include the oral antihistamines, above; and the topical steroids can help with eye symptoms, too. But if you really want to help allergic eyes, go with an eye drop. The best of the OTCs is Zaditor, which works about as well as rx Patanol, which they’re trying to replace with rx Pataday.

 

* That post didn’t win a Pulitzer. Does anyone read these footnotes?

What your kids do affects how their brains grow

Posted March 2, 2015 by Dr. Roy
Categories: In the news

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The Pediatric Insider

© 2015 Roy Benaroch, MD

A short study to review today—from Pediatrics, November 2014, “Cortical thickness maturation and duration of music training: Health-promoting activities shape brain development.” Researchers looked at MRIs scans of healthy children that were being obtained as part of a larger study of normal brain development, correlating the development of several brain areas with musical training. They found that as kids age, the ones taking music lessons had more rapid growth and maturation of brain centers involving not only motor planning and coordination, but also emotional self-control and impulse regulation.

When you exercise a muscle, it grows bigger and stronger. The same thing, essentially, happens in the brain—but it’s more complicated, because different parts of the brain do different things. What this study confirms is that at least with music, the areas of the brain exercised with musical training become “stronger”—or, at least, larger and thicker, which in brain-terms means more effective. The authors speculate that conditions like ADHD, where those same areas of brain seem relatively under-functioning, might be helped by learning to play a musical instrument.

Think about the bigger picture, too. Whatever your kids are doing, that’s the area of the brain they’re exercising. If they’re reading, they’ll become better readers; if they’re playing tennis, they’ll get better at seeing and hitting a little fuzzy yellow ball. If video games are their main hobby, they’ll get better at making fast decisions and moving their hands quickly. Katy Perry fans will get good at dancing like sharks. You get the idea. At the same time, kids who don’t practice the self-control needed to learn a musical instrument might be missing out on at least one way to help their brains mature.

Get practicing!

A few surprising vaccine myths – Betcha didn’t know!

Posted February 23, 2015 by Dr. Roy
Categories: Pediatric Insider information

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The Pediatric Insider

© 2015 Roy Benaroch, MD

Myth 1: Vaccines work by preventing disease in individuals who are vaccinated.

Nope, that’s not actually true—it’s quite wrong, but in a subtle way. And a misunderstanding of this concept, I think, has led to a lot of mischief. If people understood how vaccines really work, how they can best protect us from disease, it might help overcome some skepticism.

Vaccines do indeed prevent diseases in individuals, but that’s not how they accomplish their most important job. See, vaccines can’t be given to every individual—babies can’t get MMRs until they’re 12 month old, for instance, and many people on chemo or after transplants can’t get them at all. And even the absolute best vaccines don’t work all the time. Two doses of MMR gives 99% of recipients lifelong immunity from measles, but if you’re at Disneyland along with 40,000 other visitors that day, it means about 400 vaccinated people (1%) are not immune. That’s not a slam on the vaccine—it’s just that any medical intervention is imperfect.

So if vaccines don’t work by protecting vaccinated individuals, how do they work? By protecting populations. In a highly vaccinated population, even if measles pops up it’s got nowhere to go. If only a small number of people aren’t immune, it’s unlikely anyone else will catch it—and that means measles cannot spread, and everyone is protected. Not just the immunized, everyone. This is called “herd immunity”, and it’s the real way that vaccines work.

Vaccines aren’t about protecting just you, or your children, or just the person who gets the vaccine. Vaccines are about protecting all of us, even the babies, and the ill, and the unlucky few in whom vaccines don’t work. We’re all in this together. Maybe you’ll be the next in the neighborhood with a newborn, or maybe it will be your sister who’s diagnosed with lymphoma. Make sure your whole family is vaccinated to keep all of us safe.

 

Myth 2: Children are required to be vaccinated.

Nope. Children are required to be vaccinated in order to attend public school, just like you’re required to have a driver’s license if you want to drive. But you don’t have to get your children vaccinated as long as you make other arrangements for their education.

Even then, there are plenty of exemptions. Every state supports exempting children with legitimate medical contraindications to vaccines; almost all states support “religious objections” (though there is no common religion that’s against vaccines); many states also offer “personal belief” exemptions, too.

No government authority is forcing anyone to vaccinate, and no children are being taken away from parents who don’t vaccinate.

 

Myth 3: Vaccination, inoculation, immunization—they all mean the same thing.

In common usage, yes. But technically, they’re different.

Inoculation initially referred specifically to the historical practice of rubbing the skin of a healthy person with a little bit of crust from a smallpox victim. It was known that this could often induce a mild case of smallpox, which would protect the person from a full-blown, deadly case later. These procedures were fairy widely known especially in England in the 1700s, and remained in widespread use for hundreds of years. The word inoculate comes from the Latin root for ‘eye”, referring to the practice of grafting a bud from one plant to another.

Edward Jenner later started using scabs from cowpox to “inoculate” a milder disease, which was close enough to prevent smallpox, too. It’s thought that his inspiration was the fair, unblemished skin of English milkmaids—they universally caught cowpox as an occupational hazard, so rarely caught the disfiguring smallpox. “Vaccine” comes from the Latin word for cow, either referring to cowpox or perhaps to those fair-skinned milkmaid workers. For a while, the term “vaccination” referred only to using cowpox crusts to prevent smallpox, but later the term became more generalized to include the procedures developed by Louis Pasteur to prevent chicken cholera and anthrax.

Immunization was a later term that broadly referred to both using live infectious particles to induce active immunity, or using non-infectious toxins or other proteins. Typically, now, most of us use the terms vaccine, vaccination, and immunization pretty much interchangeably. Next time your children get one, thank a cow!

Concussions are brain injuries

Posted February 19, 2015 by Dr. Roy
Categories: Medical problems

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The Pediatric Insider

© 2015 Roy Benaroch, MD

Many parents (and even some teenagers) realize that kids are going to be using their brains at some point in their lives. I’m getting more and more questions about the effects of concussions—are they going to lead to trouble, down the road? How can they be prevented and treated?

First: let’s abandon the term “concussion.” It’s a weird word that waters down a much simpler term: traumatic brain injury. A concussion is a mild brain injury caused by trauma. So let’s just call it that, “mild traumatic brain injury.” Wordy, but those words say a lot more to parents and children than “concussion.”

How do you know a brain has been injured? Simply enough, it stops working right. A person who’s had a blow to the head followed by a period of brain-not-working has had a brain injury, a “concussion”. The symptoms could include, after the injury, a period of confusion or dizziness or a feeling that you’re “not all there.” Sometimes, but not usually, there’s a brief loss of consciousness. That worth saying again: people who’ve had a mild traumatic brain injury usually do not get knocked out. They just feel knocked around. Later, there are continued symptoms like headache, dizziness, a “fuzzy brain” feeling; sometimes there are also problems with moodiness or irritability, or trouble with sleep cycles. Again, remember, these are all symptoms of an injured brain.

People understand the concept of injuries. You injure your ankle, you expect to need to rest it. Everyone knows rest is the best way to prevent an injury from getting worse, and rest is the best way to prevent an even-worse re-injury. We instinctively know that during rehabilitation for an injured ankle, you’ll kind of walk and run funny—which puts you at risk for other injuries, too.

All of these concepts are exactly the same for concussion, and that’s easy to explain if you remember to think of a concussion as a “traumatic brain injury”. Rest is the key, to allow the brain to heal, to prevent worsening damage from continued trauma, to prevent re-injury of the brain, and to prevent injury of other body parts because you’re not performing well with an injured brain. See? Easy as an ankle to explain.

Of course, resting a brain isn’t exactly as simple as resting an ankle. We can’t use a sling or an ACE wrap (well, you can, but you’ll look weird and it won’t help.) Resting a brain means, well, brain rest: no intellectual work, no school, no physical exercise. Just like you’d rest an ankle until it felt better, resting a brain after it’s injured should continue until there are no symptoms of injury. No headaches, no sleep problems, no fuzzy brain, no dizziness, no trouble focusing. When all of these symptoms have abated, people with mild traumatic brain injuries should gradually advance to more-intense schooling and activities, step by step, until the patient is back up to full activity. If there’s a step backwards—if brain symptoms begin—do exactly what you’d do if your ankle starts to hurt again. Back off the activity and allow more time to heal.

There’s good evidence that allowing a period of time to rest and heal after a mild traumatic brain injury can help prevent re-injury and longstanding symptoms—but we don’t know exactly how long the rest should be. One recent study showed that to a point, too much rest for too long can actually worsen and extend symptoms. Once symptoms improve, it’s a good idea to start back on activities (start slow and advance step by step) rather than continue through a fixed number of days of rest. We have some work to do to fine tune and individualize the best concussion care advice.

While a single concussion, especially with appropriate treatment, is unlikely to lead to long term problems, there are some sobering concerns about people who’ve had multiple concussions. There’s an increased risk of long term cognitive decline, movement disorders, and depression. And we know many athletes under-report concussions. In one study, 30% of high school football players reported a history of concussion, but only half of those had reported the injury. There may be far more concussions injuring far more high school brains than we appreciate.

As I said, many of those brains are going to be used later. Maybe we ought to try to do a better job keeping them in good shape.


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