Efficacy and safety of intralymphatic immunotherapy in allergic rhinitis: A systematic review and meta-analysis

Background Intralymphatic immunotherapy (ILIT) is a potential treatment option for allergic rhinitis (AR). We aimed to determine the efficacy (primary outcomes) and safety (secondary outcomes) of ILIT in treating patients with AR. Methods An electronic literature search was performed using MEDLINE and Cochrane Central Register of Controlled Trials CENTRAL (from their inception to December 2020). A random-effects model was used to estimate the pooled prevalence with 95% confidence intervals. This study is registered with PROSPERO (CRD42019126271). Results We retrieved a total of 285 articles, of which 11 satisfied our inclusion criteria. There were 452 participants with age ranged from 15 to 58 years old. Intralymphatic immunotherapy was given in three doses with intervals of four weeks between doses in 10 trials. One trial gave three and six doses with an interval of two weeks. Both primary and secondary outcomes showed no difference between ILIT and placebo for all trials. There was no difference in the combined symptoms and medication score (SMD -0.51, 95% CI -1.31 to 0.28), symptoms score (SMD -0.27, 95% CI -0.91 to 0.38), medication score (SMD -6.56, 95% CI -21.48 to 8.37), rescue medication (RR 12.32, 95% CI 0.72-211.79) and the overall improvement score (MD -0.07, 95% CI -2.28 to 2.14) between ILIT and placebo. No major adverse events noted. Conclusions Intralymphatic immunotherapy possibly has a role in the treatment of AR patients. This review found it is safe but not effective, which could be contributed by the high variation amongst the trials. Future trials should involve larger numbers of participants and report standardized administration of ILIT and outcome measures.