Table ASubcutaneous immunotherapy: Summary of allergens, comparators, and main results per outcome

OutcomeNumber of StudiesNumber of ParticipantsAllergen (Number of Studies)Comparator (Number of Studies)Findings*Strength of Evidence
Asthma Studies
Asthma symptoms161,178Dust mite (7)
Cladosporium (2)
Alternaria (1)
Timothy (1)
Ragweed (1)
Rye (1)
Cat (1)
Multiple (2)
SCIT
vs. Placebo (12)
vs. Pharmacotherapy (3)
vs. No SCIT (1)
vs. SCIT continuation (1)

SCIT cluster vs. conventional (1)
The SCIT group showed greater improvement than the comparators in all studies.High that SCIT improves asthma symptoms more than comparators
Asthma plus rhinitis/ rhinoconjunctivitis symptoms5175Parietaria (1)
Alternaria (1)
Birch (1)
Timothy (1)
Cat (1)
SCIT
vs. Placebo (4)
vs. Pharmacotherapy (1)
The SCIT groups consistently showed greater improvement than the comparators in all studies.Moderate that SCIT improves rhinoconjunctivitis symptoms more than comparators
Asthma medication scores121,062Dust mite (6)
Ragweed (1)
Rye (1)
Cladosporium (1)
Birch (1)
Multiple (2)
SCIT
vs. Placebo (8)
vs. Pharmacotherapy (3)
vs. No SIT (1)
9 studies showed greater reduction in medication use in the SCIT group; 5 were statistically significant (3 when compared with placebo, and 2 when compared with pharmacotherapy).
5 studies showed no significant difference between groups.
1 study did not report statistics.
4 studies did not report results from direct comparison between groups.**
High that SCIT improves asthma medication scores more than comparators
Asthma plus rhinitis/ rhinoconjunctivitis medication scores5203Parietaria (1)
Birch (1)
Timothy (1)
Cladosporium (1)
Alternaria (1)
SCIT
vs. Placebo (4)
vs. Pharmacotherapy (1)
All studies showed a significant reduction in asthma and rhinoconjunctivitis medication consumption in the SCIT group when compared with controls.High that SCIT improves asthma plus rhinitis/ rhinoconjunctivitis medication scores more than comparators
Combined asthma symptom-medication scores6196Dust mite (2)
Alternaria (2)
Cat (1)
Cladosporium (1)
SCIT
vs. Placebo (5)
vs. Pharmacotherapy (1)
vs. SCIT (1)–placebo controlled
All placebo controlled studies demonstrated significant improvement in the SCIT group. The other study showed no significant difference.Low that SCIT improves combined asthma symptom and medication scores more than comparators
Rhinitis/Rhinoconjuctivitis Studies
Rhinitis/rhinoconjunctivitis symptoms261,764Dust mite (4)
Timothy (4)
Ragweed (3)
Parietaria (2)
Grass mix (2)
Alternaria (2)
Tree (2)
Cladosporium (1)
Cat (1)
Multiple (5)
SCIT
vs. Placebo (23)
vs. Pharmacotherapy (2)
vs. SCIT (4)
23 studies showed greater improvement in symptoms favoring the SCIT group; 19 were statistically significant (18 when compared with placebo, and 1 when compared with pharmacotherapy).
7 studies showed no statistically significant difference.
High that SCIT improves rhinitis/ rhinoconjunctivitis symptoms more than comparators
Conjunctivitis symptoms141,104Timothy (4)
Grass mix (2)
Parietaria (1)
Cladosporium (1)
Alternaria (2)
Cat (1)
Multiple (3)
SCIT
vs. Placebo (11)
vs. SCIT (2)–both placebo controlled
vs. Pharmacotherapy (1)
13 studies showed greater improvement in symptoms favoring the SCIT group; 6 were statistically significant.
8 studies showed no statistically significant difference.
High that SCIT improves conjunctivitis symptoms more than comparators
Combined symptom score (bronchial, nasal, ocular; rhinitis studies only)6591Grass mix (2)
Alternaria (1)
Timothy (1)
Mountain cedar (1)
Dust mite (1)
SCIT
vs. Placebo (6)
vs. SIT (1)
5 studies showed greater improvement in symptoms in the SCIT group than in the comparator group.
1 study showed improvement in the SCIT arm only when comparing pretreatment with post-treatment scores.**
High that SCIT improves combined symptom scores more than comparators
Rhinitis/rhinoconjunctivitis medication scores10564Dust mite (2)
Timothy (2)
Ragweed (1)
Parietaria (1)
Grass mix (2)
Tree (1)
Multiple (1)
SCIT
vs. Placebo (8)
vs. SCIT (3)–all were placebo controlled
vs. pharmacotherapy (1)
All studies showed greater reduction in medication consumption in the SCIT arm; 7 of the studies were statistically significant (6 when compared with placebo, and 1 when compared with pharmacotherapy).Moderate that SCIT improves rhinitis/ rhinoconjunctivitis medication
scores more than comparators
Rhinitis/rhinoconjunctivitis plus asthma medication scores (rhinitis studies only)11768Parietaria (3)
Timothy (2)
Grass mix (2)
Ragweed (1)
Alternaria (1)
Dust mite (1)
Multiple (1)
SCIT
vs. Placebo (11)
vs. SCIT (1)–placebo controlled
9 studies showed significant reduction in asthma and rhinoconjunctivitis medication consumption in the SCIT group. 2 studies showed no difference.High that SCIT improves rhinitis/ rhinoconjunctivitis plus asthma medication scores more than comparators
Combined rhinitis symptom-medication score6400Grass mix (1)
Ragweed (1)
Alternaria (2)
Date tree (1)
Grass (1)
SCIT
vs. Placebo (5)
vs. SCIT (2), (1 conventional, 1 crude)
4 studies demonstrated significant improvement in the SCIT group. 2 studies showed no difference.Low that SCIT improves combined rhinitis medication scores more than comparators
Disease-specific quality of life6889Alternaria (2)
Parietaria (1)
Timothy (1)
Grass mix (1)
Multiple (1)
SCIT
vs. Placebo (4)
vs. Pharmacotherapy (1)
vs. SCIT (1)–placebo controlled
All studies showed greater improvement in quality of life favoring the SCIT group. 4 studies reported statistically significant improvement in disease-specific quality of life when compared with placebo. The other 2 studies found no improvement.High that SCIT improves disease-specific quality of life more than comparators
Secondary Outcomes
Pulmonary function test results131,024Dust mite (6)
Cat (2)
Birch (2)
Ragweed (1)
Cladosporium (1)
Multiple (1)
SCIT
vs. Placebo (9)
vs. Pharmacotherapy (2)
vs. No SCIT (1)

SCIT cluster vs. conventional (1)
There were variable and inconsistent findings.Not graded
Specific allergen bronchial reactivitiy17514Dust mite (9)
Cat (3)
Ragweed (1)
Birch (1)
Cladosporium (1)
Dog (1)
Multiple (1)
SCIT
vs. Placebo (15)
vs. Pharmacotherapy (2)
11 studies demonstrated significant decreases in bronchial reactivity favoring the SCIT group over the comparison group.
6 studies showed no difference.
Not graded
Nonspecific bronchial reactivity16750Dust mite (7)
Cat (3)
Multiple (2)
Birch (2)
Timothy (1) Alternaria (1)
SCIT
vs. Placebo (10)
vs. Pharmacotherapy (5)
vs. Conventional (1)
Two studies demonstrated significant decreases in bronchial reactivity favoring the SCIT group over the comparison group.Not graded

SCIT = subcutaneous immunotherapy; SIT = allergen-specific immunotherapy

*

This column presents a summary of the relevant findings. Numbers in this column may not match the total numbers of studies included per outcome; for some outcomes, studies reported more than one comparison per outcome (e.g., different dosage groups).

**

Results from pre-post comparisons did not contribute to the evidence grades, as their design was not as strong as head-to-head comparisons. We included these results in the tables for informational purposes only.

From: Executive Summary

Cover of Allergen-Specific Immunotherapy for the Treatment of Allergic Rhinoconjunctivitis and/or Asthma: Comparative Effectiveness Review
Allergen-Specific Immunotherapy for the Treatment of Allergic Rhinoconjunctivitis and/or Asthma: Comparative Effectiveness Review [Internet].
Comparative Effectiveness Reviews, No. 111.
Lin SY, Erekosima N, Suarez-Cuervo C, et al.

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