In patients seeking treatment for moderate-to-severe respiratory allergies, polysensitization is more prevalent (range, 50% to 80%) than monosensitization in both the United States and Europe.
Europe vs. U.S. practices
In allergen immunotherapy there is debate as to whether:
1. polysensitized patients are best treated with many allergens simultaneously (chosen according to the sensitization profile, a predominantly North American approach)
2. a single allergen is the best approach (chosen according to the most clinically problematic allergy, a predominantly European approach)
In Europe most formulations are single-allergen extracts, whereas preparations in the United States contain an average of 8 different components.
The prevailing view in Europe is that a polysensitized patient is not necessarily polyallergic. The most troublesome allergy is then treated with a single-allergen preparation.
The predominant view in the United States is that there is an advantage in treating as many of the patient’s actual or potential sensitizations/allergies as possible. American allergists prefer to include all relevant allergens because of the concern over the significant time investment needed in SCIT, especially during the build-up phase. The standard US practice is to treat all relevant allergens.
What to do?
In patients with seasonal allergic rhinitis, subcutaneously and sublingually administered single-allergen preparations (grass pollen extracts) are clearly efficacious and safe.
Multiallergen immunotherapy faces formulation issues in a new era of registered and standardized allergen immunotherapies with numerous quality, efficacy, and safety constraints.
The US practice guidelines recommend that physicians treat with “relevant” allergens, although the interpretation of “relevant” can be problematic. For grass pollen allergens, trials show that polysensitized patients benefit just as much from single-allergen immunotherapy as monosensitized patients.
Multiple-allergen and single-allergen immunotherapy strategies in polysensitized patients: Looking at the published evidence. JACI, 2012
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