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RUSH Better Than Sublingual or Subcutaneous Immunotherapy – Nov. 8, 2005
Jane Neff Rollins, MSPH
Medscape Medical News 2005. © 2005 Medscape
Nov. 8, 2005 (Anaheim) – A one-day rush schedule (RUSH) of immunotherapy may be better than sublingual immunotherapy (SLIT) and standard subcutaneous immunotherapy (SCIT), according to a presentation given by Richard F. Hersscher, MD, at the annual meeting of the American College of Allergy, Asthma & Immunology.
“SLIT efficacy appears equal to standard injection therapy. SLIT dosing that is 15 times the cumulative dose used with standard injection performed well in our patients,” Dr. Herrscher, medical director of a multiphysician group practice in Dallas, Texas, told Medscape.
RUSH immunotherapy is emerging in clinical practice in the U.S. SLIT is widely used in Europe on the basis of published trials that showed efficacy similar to SCIT. SLIT can be administered at home because of low reaction rates, but it has not been evaluated with allergen extracts in the U.S.
The purpose of the study was to evaluate how alternative schedules of RUSH and SLIT compared with SCIT in terms of compliance, clinical efficacy, and safety. Patients with allergic rhinitis/asthma who started immunotherapy between July 2003 and December 2004 filled out a questionnaire to evaluate the three delivery methods.
All patients received multi-allergen extracts starting at 1:1000 or lower dilution, building to undiluted maintenance vials. SCIT injections were once or twice weekly for two months, weekly for 10 months, then twice monthly at maintenance. The RUSH one-day protocol started at 1:1000 dilution, with doses doubling at intervals for eight hours until the dose reached full strength (.05 cc) by the end of day 1, followed by a build-up to 0.50 cc full strength once weekly, then monthly injections at maintenance. SLIT patients held drops sublingually for two minutes then swallowed on a daily or every other day build-up basis, then three times weekly at maintenance. Up to 10 allergens could be included in each dose, and the maximum maintenance dose was 10 drops.
One of the barriers to incorporating SLIT in clinical practice in the U.S. is the lack of consistent evidence to support establishing standard doses. In Europe, investigators are dosing at 5, 50, or even 1,000 times the suggested injected dose. In this study, patients on SLIT received a mean monthly allergen of 405 µg Amb a, approximately 15 times the mean monthly dose used with SCIT.
Sample sizes for the treatment groups were 84 patients in the RUSH group, 174 patients in the SCIT group, and 97 patients in the SLIT group. Participants in the RUSH group were older (mean age, 32.5 years) than those in the SCIT (24.4 years) and SLIT (18.2 years) groups. Patients on RUSH may have been more satisfied and thus had better compliance: more patients remained on therapy in the RUSH group (74%) than those electing SCIT (63%) or SLIT (60%). Questionnaire responders were stratified based on duration of therapy: less than 12 months and more than 12 months.
Patients on therapy less than 12 months experienced a greater combined symptom/medication reduction with RUSH (43.1%) than with SCIT (28.1%) or SLIT (21.4%; P < .001 overall). Patients on therapy more than 12 months also experienced greater symptom/medication reduction with RUSH (50%) than those on SCIT (34.9%; P < .03) or SLIT (34.7; P < .03). After 12 months of therapy, however, patients receiving SLIT achieved symptom/medication reduction equal to those receiving SCIT. Systemic reactions (including urticaria, wheezing, runny nose, or nonstop sneezing) were reported in RUSH (16%), SCIT (6%), and SLIT (0.7%) groups.
“Patients really like [it] when we offer them options,” Dr. Herrscher told Medscape. “We tell them sublingual is newer, it’s a bit unknown, it may not work quite as well, especially early on, but it’s got this huge convenience factor. There are standard injections which have been around forever and are fairly safe. RUSH works much better than anything but has a higher reaction rate.”
The implications of this study are that clinicians may benefit their patients by offering RUSH protocols and SLIT as alternatives to standard therapy. It is possible, for instance, to switch a patient to SLIT if the patient develops systemic reactions shots or does not have time for once- weekly office visits.
This study was independently funded. Dr. Herrscher had nothing to disclose.
ACAAI Annual Meeting: Abstract 54. Presented Nov. 7, 2005.
Reviewed by Helen Fosam, PhD
* This treatment is not approved by the FDA