PURPOSE OF THE STUDY.
To compare the efficacy of subcutaneous (SCIT) and sublingual immunotherapy (SLIT) to grass by meta-analysis of double-blind, placebo-controlled trials.
Among 36 studies selected for this meta-analysis, 14 included children.
An electronic literature search identified 36 randomized controlled trials (RCTs) comparing SCIT and SLIT to placebo for grass pollinosis. All the studies assessed symptom scores and 31 assessed medication scores as outcome measures. To standardized comparative studies, the authors used the “standard mean difference” method (SMD) to compare SCIT or SLIT versus placebo. A “fail-safe” number (the number of insignificant or missing studies that would need to be added to a meta-analysis to reduce a significant result to insignificance) calculation was performed.
The 36 RCTs (22 SLIT [10 drops, 12 tablets], 14 SCIT) included 3014 treated patients and 2768 patients given placebo. Nine SLIT studies and 5 SCIT studies included children. There was great variation in the number of subjects enrolled (15–943) and the duration of treatment (1.5–36.0 months). All RCTs of SLIT showed improved symptom scores as compared with placebo, but only 3 of 10 studies using SLIT drops, 8 of 12 using SLIT tablets, and 12 of 14 using SCIT reached statistical significance. The SMDs indicated a significant and considerable benefit from SCIT and mild-moderate benefit from SLIT. The fail-safe number for symptom scores was 530 for SLIT and 232 for SCIT studies. Medication scores were obtained in 20 SLIT and 11 SCIT RCTs. The pooled data for the SCIT and SLIT studies showed significant reduction in SMD of symptoms scores (SLIT drops: –0.37, SLIT tablets: –0.30, SCIT: –0.58). However, only ∼50% of the studies of each method showed a statistically significant reduction in medication score as compared with placebo. The fail-safe number for medication scores was 384 for SLIT and 66 for SCIT studies. There were 0.86 adverse events/patient reported for patients receiving SCIT and 2.13 adverse events/patient reported in those receiving SLIT. A “robust analysis” done by eliminating each study from the total group did not change the results, indicating that no one study was solely responsible for the findings.
In patients with grass-induced seasonal allergic rhinoconjunctivitis, SCIT is more effective than SLIT in reducing symptoms and the need for rescue medication.
SLIT is an area of recent intense research and potentially an attractive alternative to SCIT for children. For a small handful of allergens, SLIT has been shown to be more effective than placebo when given in much higher total monthly doses than are given by SCIT. But, we do not treat our patients with placebo. We treat them with approved materials. The high-dose materials used in those European studies are not approved in the United States. Low-dose SLIT (as is available) has not been shown to be more effective than placebo. In SCIT, numerous allergens are given at the same time with time-proven efficacy. The results of a limited number of studies using SLIT to numerous allergens given at once are not impressive. Until high-dose SLIT has been proven superior to SCIT, it should not be practiced.
- Copyright © 2013 by the American Academy of Pediatrics