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Wise et al.

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received 3 or 4 years of SCIT with Timothy grass extract. 1656 Subjects were randomized to continue maintenance SCIT or receive placebo for 3 years. There was no difference in symptom/medication scores over the 3 grass pollen seasons between those receiving and not receiving Timothy extract injections. In another trial, grass SCIT was discontinued in 108 grass-sensitive patients who had responded well to the treatment after 3 or 4 years of SCIT. 1657 The patients were followed through up to 4 grass pollen seasons looking for relapse. Approximately 30% relapsed by the third grass pollen season, with few more subsequently relapsing. In the 2 studies discussed in the preceding paragraph, 1656,1657 3 or 4 years of SCIT with grass extract induced remissions that persisted in most of the subjects for at least 3 years. There are only a few studies that look at longer or shorter periods of treatment. A study that compared 3 or 5 years of SCIT with HDM extract found significant improvement after 3 years but added clinical improvement in rhinitis after 5 years of SCIT. 1658 Safety.: Information regarding the occurrence of fatal reactions to SCIT was obtained retrospectively by the Immunotherapy Committee of the AAAAI by periodic surveys of its members from 1985 to 2001 1659,1660 and by an online website since 2008. 1644 The earlier retrospective surveys suggested that a fatal reaction occurs with every 2 to 2.5 million injection visits. 1659,1660 The online survey elicited information on 2 fatal reactions in 28.9 million injection visits, which was thought to represent an improvement due to more careful monitoring of patients with asthma. 1644 The rate of systemic reactions has remained steady, with 1.9% of patients experiencing a systemic reaction, most mild, but with 0.08% experiencing a grade 3 and 0.02% a grade 4 reaction. 1644 The occurrence and size of local reactions do not predict the occurrence of a systemic reaction with the next injection. 1661,1662 Cost effectiveness.: SCIT can be administered for 3 to 5 years with continuing relief of symptoms for years after discontinuation. Pharmacotherapy, on the other hand, must be continued indefinitely, since it has no disease-modifying activity. Because of this difference, the initial higher cost of SCIT may be offset by the continuing benefit after it is stopped. This factored into a decision-making analysis that suggested if a patient with SAR requiring nasal steroids 6 months per year is seen before age 41 years, the cost will be less in the long term if they are placed on SCIT. 1662,1663 If the patient has perennial need for nasal steroids, and they are less than 60 years of age, the most cost effective approach is SCIT. Another cost-effectiveness analysis found that SCIT for SAR may be more effective and less expensive than pharmacotherapy from the societal perspective when costs of productivity loss are considered. 1664 A retrospective study compared U.S. Medicaid-treated adults and children who were newly diagnosed with AR and were or were not placed on AIT. Eighteen month follow-up revealed 30% and 42% healthcare cost savings, respectively, in the AIT treated patients. 1665 • Aggregate Grade of Evidence for SCIT in the treatment of AR: A (Level 1a: 3 recent studies listed; Level 1b: 5 recent studies listed; Table IX.D.3-1). Of note, due to the large body of literature supporting SCIT as a treatment for AR, only recent systematic reviews and select double-blind, placebo-controlled RCTs are

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Int Forum Allergy Rhinol . Author manuscript; available in PMC 2020 June 10.