Head-to-head comparison between subcutaneous and sublingual immunotherapy in perennial allergic rhinitis: A systematic review and meta-analysis

Purpose: Few meta-analyses of head-to-head comparisons between subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) for perennial allergic rhinitis (AR) have been performed so far. This study aimed to compare the efficacy, safety, and adherence of SCIT and SLIT in patients with house dust mite (HDM)-sensitized AR through a meta-analysis of head-to-head comparative studies. Methods: A meta-analysis based on direct comparisons of SCIT and SLIT in HDM-sensitized AR was performed, using randomized controlled trials (RCTs) and nonrandomized studies (NRSs), on efficacy, safety, and adherence, which had been published until April 30, 2021. Treatment efficacy was calculated as the standardized mean difference in symptoms and medication scores after treatment between SCIT and SLIT. Safety and adherence to treatment were compared with the relative risk (RR) of SCIT and SLIT. Results: Six RCTs and 3 NRS scores were analyzed. No statistically significant difference was noticed in improvement in symptoms and medication scores between SCIT and SLIT groups. Systemic adverse events occurred more frequently in SCIT than in SLIT in both RCT (RR, 3.97; 95% confidence interval [CI], 0.50-31.57) and NRS (RR, 5.48; 95% CI, 1.94-15.50). SCIT showed significantly higher adherence than did SLIT (RR, 1.16; 95% CI, 0.92-1.47). Conclusion: No significant difference in efficacy was noticed between the 2 modalities for HDM-sensitized AR. However, SLIT had significantly lower number of systemic adverse reactions, and SCIT had more preferable adherence. (Allergy Asthma Respir Dis 2024;12:17-25)