In 2014, a group from the San Diego Medical Centre led by Eric Macy MD, published an interesting retrospective study. They looked at healthcare use and prevalence of serious infections among 51,582 hospitalized patients with penicillin allergy. They found that these patients with penicillin allergy had an increased exposure to more broad-spectrum antibiotic, suffered more infections and were re-admitted more.
Coincidence? Not at all.
For years, it has been known that even though about 10% of the US population reports an allergy to penicillin, only about 1% of these cases are true immune-mediated allergies. Also, in cases of true immune-mediated reactions, 80% lose their sensitivity after 10 years. This matters because when a patient reports a penicillin allergy, most hospitals do not test for the patient to prove the veracity of that claim. Instead, patients are placed on broad-spectrum antibiotics like vancomycin and the fluoroquinolones. The use of these more powerful antibiotics leads to higher healthcare costs, increased risk for antibiotic resistance, and suboptimal antibiotic therapy. As we all are realizing, the issue of antibiotic resistance is no joke. Heard of Colistin-resistant E. coli?
Overall in the US, the incidence of such false drug allergies is on the increase and the consequences can be dire, as exemplified in the case of penicillin.
Now an adverse reaction to a drug is seen as any unwanted and untoward effect of said drug. These reactions include allergic reactions as well intolerance to it. Even the inability of the drug to work falls under adverse drug reactions.
Now a true drug allergy is mediated by the body’s immune system through antibodies – IgE as well as the T-cells. Since these are immune reactions, a true allergic reaction is not seen the first time one takes the drug. The body must be sensitized first. Where IgE mediates the really fast reactions like hives and angioedema, the T-cell mediated reactions takes days and weeks to become evident.
Data shows that less than 5% of adverse drug reactions are due to true immune reactions – so true allergies.
Yet, we are seeing patients with the most interesting allergies everyday. We’ve all heard them:
“Epinephrine (adrenaline) makes my heart race!”
“Beta-Blockers make my heart beat really slow!’
“Bernadryl made me sleepy!”
“Predinisone made me jumpy!”
“Aspirin tore up my intestines!”
These pseudo-allergies hinder optimal patient care in a lot of ways. They prevent the use of the the best drugs for the patient.
Several factors are contributing to this situation. A common factor buttressing all of this, is that more Americans are taking more drugs daily. One is going to see more adverse drug reactions.
The causes then split into patient and provider-related factors. Let’s do some scenarios (based on true events);
A patient notices a “bad” event while taking a drug A. He/She makes the erroneous connection that she has an allergy to drug A. Next time she is at her doctor’s or the hospital, she is asked by the triaging or admitting nurse about her allergies. She states she is allergic to drug A. The nurse just records it without further questioning and it is part of her history.
The patient call her doctor to tell him/her that she had a reaction to drug A. The doctor unwilling to bore and really find out the cause of said reaction goes, “You might be allergic to it. Let’s try drug B.”
A patient in the hospital is in pain after surgery. She is also having nausea. The physician orders a dose of narcotics to be given with an anti-emetic. The nurse does that. Fifteen minutes later, the patient is found apneic but successfully resuscitated. A day later, the patient is told she had an allergic reaction to the anti-emetic.
Years ago, a patient received novocaine at his/her dentist reaction office. There was an adverse reaction. According to the patient, she lost consciousness. She was later told she was allergic to all local anesthetics. It doesn’t matter that it might not have been the drug but where it might have been injected. Or that novocaine is an ester-based local anesthetic that is allergenic but quite different from the amide-based ones like lidocaine that are not.
A patient receives a peripheral nerve block for shoulder surgery. She emerges from general anesthesia in pain and nauseous. Well, the block didn’t work so the patient had to be given narcotics intraoperatively. In recovery, she is given more narcotics to treat her pain and ondansetron to treat the nausea. She erroneously concludes afterwards that the combination of local anesthetic, narcotics and ondanstron made her postoperative course so uncomfortable. She must be allergic to all those drugs. They appeared as allergies on her next visit!
Allergies have become a screen that practitioners can hide behind. They use it to get out of figuring out what is really going on or protecting themselves from a possible lawsuit. Patients on the other hand are quick to jump to erroneous conclusion. Conclusions that affect their care negatively.
Maybe it is time for most hospitals to employ an Allergy Czar. maybe institute an Allergy Tribunal. Then frankly, I’m developing an allergy to all these allergies.