March 20, 2011

Home Allergy Shots

DISCLAIMER: This post is not meant to condone or promote allergy shots to be given at home. It is meant to promote discussion and make patients aware of the issues involved.

Allergy shots, unlike medications like claritin and flonase, offer patients with significant allergies a way to potentially be cured of their misery without the need for daily medication use. However, there is a small, but substantial risk for anaphylaxis and even death with allergy shot administration. After all, a patient is being injected with the very substances that cause their allergies. As such, many allergists will allow allergy shots to be administered ONLY within a medical setting. Also, the American Academy of Allergy Asthma and Immunology (AAAAI) specifically forbids allergy shots to be administered at home.

Furthermore, the allergen extracts used to make the allergy vial serum used for allergy shots carry a black box warning on the medication package insert:
"This product is intended for use only by physicians who are experienced in the administration of high dose allergy injection therapy, or for use under the guidance of an allergist. Allergenic extracts may potentially elicit a severe life-threatening systemic reaction, rarely resulting in death. Therefore, emergency measures and personnel trained in their use must be available immediately in the event of such a reaction. Patients should be instructed to recognize adverse reaction symptoms, be observed in the office for at least 30 minutes after skin testing or treatment, and be cautioned to contact the physician's office if symptoms occur. Standardized glycerinated extracts may be more potent than regular extracts and therefore are not directly interchangeable with non-standardized extracts, or other manufacturers' products. Patients with cardiovascular diseases and/or pulmonary diseases such as symptomatic unstable, steroid dependent asthma, and/or those who are receiving cardiovascular drugs such as beta blockers, may be at higher risk for severe adverse reactions. These patients may also be more refractory to the normal allergy treatment regimen. Patients should be treated only if the benefit of treatment outweighs the risks. Patients on beta blockers may be more reactive to allergens given for testing or treatment and may be unresponsive to the usual doses of epinephrine used to treat allergic reactions. This product should never be injected intravenously."
The downside of allergy shots is that they are given 1-2X per week not just for a month or two, but for YEARS. If shots are given only within a medical facility, the patient must commit a significant amount of time, travel, and gas in order to complete a shot series. There is also the time missed from work. In essence, the patient must approach allergy shots like a part-time job.

Given all this... what are the actual risks of anaphylaxis and death from allergy shots?

VERY small...

In one Mayo Clinic study on 79,593 immunotherapy injections over a 10-year period showed the incidence of adverse reactions to be less than two-tenths of 1 percent (0.137 percent). Most of the reactions were mild and responded to immediate medical treatment. There were no fatalities.

More than 1 million injections were given without a fatality to 8,706 patients in allergy clinics at Roosevelt Hospital, New York City, between 1935 and 1955.

Worldwide, there were only 35 deaths reported from allergy shots between 1985 - 1993. It has been estimated that during that period there were 52.3 million immunotherapy procedures, making the incidence of fatality less than one per million (0.6692 per million). Data recently compiled by the Allergen Products Manufacturers Association (APMA) estimated the incidence of fatalities to be about three per 190 million annual injections, or approximately one per 63 million injections.

Now compare this to other medical interventions. Approximately 1 in 5000 exposures to a IV dose of penicillin or cephalosporin antibiotic causes anaphylaxis of which more than 100 deaths per year are reported in the United States. Fatal reactions to penicillin have ranged from 0.4 fatalities per million injections to 1 fatality per 7.5 million injections.

One to 2% of people receiving IV contrast (for a CT scan) experience some sort of systemic reaction. The majority of these reactions are minor, but fatalities have occurred in about 1 in 13,000 to 1 in 75,000 procedures in the 1980s (a more recent study has shown a decrease of 1 fatality in 169,000 procedures).

So... the main question now is should home allergy shots ever be allowed?

There are two ways of answering this question.

The first way is to consider any fatality due to an allergy shot (no matter how extremely rare) to be unacceptable, especially when considering the disease being treated -- allergies -- to be a quality of life issue rather than a life/death issue (heart transplant surgery). There is also that black box warning mentioned above.

The other way to view the answer is to consider things in perspective. There are MANY quality of life activities that people perform that has a risk of severe bodily harm if not death. Swimming results in 1,150 deaths per year in the United States alone. There are about 43,000 fatalities per year from car accidents.

Also, if one takes the stringent view that any fatality due to an allergy shot to be unacceptable, than patients should be monitored in a medical facility for not just 30 minutes or less, but 24 hours as late reactions can still occur the following day after an allergy shot! Indeed, in England, patients are required to wait under observation for anaphylaxis as long as ONE HOUR after each and every injection!!! In fact, the one hour observation was an improvement over the TWO hours that was imposed initially. Read more about this here.

So why draw the line at 20 minutes (or more) as recommended by the AAAAI in the United States? It's because the vast majority of severe reactions occur within the first 30 minutes. Beyond 30 minutes, severe reactions become less common (but NOT zero). Well, severe reactions are not very common to begin with... and if allergy shots must be given in a medical facility due to this concern... than should it not follow logically that no matter how rare the possibility, that patients MUST be observed for 24 hours no matter how small the risk of anaphylaxis than?

Why state that allergy shots must be given in a medical facility due to small, but possible risk of severe reaction on the one hand, and than state that there is a small, but acceptable risk of severe reaction after 20+ minutes of observation in a medical facility?

It is just through this thought process that some physicians who provide allergy shots allow home injections. At this time, it is estimated that about 15% of allergists allow home injections (based on a blinded survey of allergists).

IF home allergy shots are allowed (and this is by no means a recommendation or a statement condoning home allergy shots, but just saying in a hypothetical sense), it should be done only in carefully selected patients:

- Are on maintenance regimen (allergy shots are not being increased)
- No significant reactions during buildup and maintenance
- Proper training in administration (just like diabetics are trained to give themselves their shots)
- Epi-pen available and understanding in how to use
- In-office allergy shot with post-injection monitoring for a period of time with every new vial
- Only in adults
- CONSENT signed by patient informing of the risks as well as black box warning

Systemic reactions to immunotherapy at the Mayo Clinic. J Allergy Clin Immunol 1997; 99:S66.

The risk of inducing constitutional reactions in allergic patients. J Allergy 1957; 28:251-261.

Deaths associated with allergenic extracts. FDA Medical Bulletin 24, May 1994.

Allergenic extracts used in immunotherapy fatalities. J Allergy Clin Immunol 1997; 99:S67.

Nature and extent of penicillin side-reactions with particular references to fatalities from anaphylactic shock. Bull WHO 1968; 38:159.

Mortality during excretory urography: Mayo Clinic Experience. AJR 1982; 139:919-922.

Reactions to ionic and nonionic contrast media: A report from the Japanese Committee on the Safety of Contrast Media. Radiology 1990; 175:621-628.

Fauquier blog
Fauquier ENT

Dr. Christopher Chang is a private practice otolaryngology, head & neck surgeon specializing in the treatment of problems related to the ear, nose, and throat. Located in Warrenton, VA about 45 minutes west of Washington DC, he also provides inhalant allergy testing/treatment, hearing tests, and dispenses hearing aids.

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