Long-term protection after stopping venom immunotherapy: results of re-stings in 200 patients.
BACKGROUND
Venom immunotherapy (VIT) protects most patients allergic to Hymenoptera stings while booster injections are continued. Few data on long-term protection after discontinuation of treatment are available.


OBJECTIVE
We sought to investigate protection from re-stings over a prolonged period after stopping VIT.


METHODS
Re-sting data were obtained from 200 of 322 patients in whom VIT had been stopped between 1988 and 1992 after a duration of at least 3 years. The 25 (12.5%) patients who again developed systemic allergic reactions were compared with 50 matched patients without re-sting reactions. Clinical data and diagnostic parameters (i.e., skin sensitivity and specific IgE and IgG) were studied.


RESULTS
Of the 25 patients who had re-sting reactions, 19 had been treated with bee venom (relapse rate, 15.8%), and six had been treated with Vespula venom (relapse rate, 7.5%). About half of the re-sting reactions occurred on the first resting after stopping VIT. Most of these reactions were mild, whereas the majority of reactions occurring after repeated re-stings were severe. When re-sting reactions were related to the total re-stings per year, an accumulation of sting reactions was observed in years 3 to 5 after stopping VIT. Patients with re-sting reactions had been receiving VIT for a significantly shorter duration (43.35 months) than those with continued protection (54.65 months) (p < 0.01). Of the diagnostic parameters, only a negative intracutaneous skin test at 10(-3) gm/L predicted long-term protection reliably.


CONCLUSIONS
Venom immunotherapy of 3 to 5 years duration induces long-term protection in most patients. In rare occasions severe re-sting reactions may, however, occur, especially after repeated re-stings.
Lerch
E
E
Division of Internal Medicine, Zieglerspital, Bern, Switzerland.
Müller
U R
UR
D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology*; D001514:Bee Venoms / Q000276:immunology*; D001733:Bites and Stings / Q000276:immunology*; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000175:diagnosis / Q000276:immunology / Q000517:prevention & control / Q000628:therapy*; D007167:Immunotherapy; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D013997:Time Factors; D014862:Wasp Venoms / Q000276:immunology*
D000485:Allergens; D001514:Bee Venoms; D014862:Wasp Venoms