Thursday, April 15, 2010

Insurance Mandated Limits on Prick and Intradermal Skin Testing

The best way to determine if a patient has allergies to a substance is to directly challenge the subject with allergens on the suspected tissue.  For example, to determine if a patient has anaphylactic reactions to peanuts, we would feed the patient some peanuts and see what happens next.  This is called a food challenge.  Another example, to determine how allergic a patient is to oak pollen, we place drops of oak pollen into the patient's eye and measure the results.  This is called a conjunctival challenge.  Neither are practical for testing more than one substance at a time and then there's the danger and discomfort to the patient.  Thus, we rarely use challenges to diagnose patients with allergies.

Skin tests are the second best way of: determining the presence of allergic antibodies to a substance and  providing some guidance as to the amount of antibodies present.  Skin tests can provide evidence as to: 1) does the patient have allergies?  yes or no; 2) to what substances (allergens) is the patient allergic?; 3) how badly is the patient allergic to those allergens? The skin's immune system responds about 80-95% of the time just like the respiratory and gastrointestinal tracts.  This is the practical standard used by all board certified medical allergists.  Blood tests, called RAST or PRIST, are not as accurate.

Let's define the two types of skin testing.  First, prick skin tests involve gently pressing on the skin with a plastic device.  The device has a drop of an allergen on the end.  There is no bleeding and minimal discomfort.  Second, intradermal skin tests involve using a 25-gauge needle, which at about 0.5 mm diameter is nearly the smallest diameter needle used in medicine, to place a small amount of allergen under the skin, to see if a small and measureable allergic reaction occurs.

Every insurance companies has placed limits on the amount of skin testing, so I consider this when I order skin tests.  I try to keep the number of tests below the mandated limits and rarely exceed this number. Below is some examples I have researched for some major insurance companies.

Insurance Prick Tests Intradermal Tests Comments
Medicare 80 No limit
Super Med 99 No limit
BC BS of Alabamaany +any: to a maximum of 65 total (terrible)
Medicaid (straight, not HMO) 143 No limit
United Health Care (UHC) 75 per day 75 per day

This table isn't meant to be law.  I excluded Aetna, Cigna, and Humana, because there is no discernable pattern to my eyes anyways of how many tests are covered.  Check your individual insurance benefits before you have skin testing.  What is law now is that everyone's benefit's are made as incomprehensible as possible, and yet you are responsible for your own health.  I am just giving some examples to help patients to prepare for a productive visit to their board certified medical allergist.  (Note 1: hopefully me.  Note 2: always verify that your physicians are board certified.  I can tell you every physician makes sure the physician they see is board certified.  This means it is important to us!)

Readers, you'll be hard pressed to ever find a post like this on the WWW.  I couldn't.  I hope this helps you understand the process better. 
Your Allergy Dude

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