Intranasal Versus Oral Treatments for Allergic Rhinitis: A Systematic Review with Meta-Analysis

Background Treatments for allergic rhinitis include intranasal or oral medications. Objective To perform a systematic review with meta-analysis comparing the effectiveness of intranasal corticosteroids or antihistamines versus oral antihistamines or leukotriene receptor antagonists in improving allergic rhinitis symptoms and quality of life. Methods We searched four bibliographic databases and three clinical trial datasets for randomised controlled trials (i) assessing patients ≥12 years old with seasonal or perennial allergic rhinitis, and (ii) comparing intranasal corticosteroids or antihistamines versus oral antihistamines or leukotriene receptor antagonists. We performed a meta-analysis of the Total Nasal Symptom Score (TNSS), Total Ocular Symptom Score (TOSS), Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ), development of adverse events, and withdrawals due to adverse events. Certainty of evidence was assessed using GRADE. Results We included 35 studies, most of which assessed patients with seasonal allergic rhinitis and displayed an unclear risk of bias. Superiority of intranasal treatments was found for all assessed outcomes. Intranasal corticosteroids were more effective than oral antihistamines at improving the TNSS (MD=-0.86; 95%CI=-1.21;-0.51; I2=70%), TOSS (MD=-0.36; 95%CI=-0.56;-0.17; I2=0%) and RQLQ (MD=-0.88; 95%CI=-1.15;-0.61; I2=0%), being mostly associated with clinically meaningful improvements. Superiority of intranasal corticosteroids at improving the TNSS was also found against oral leukotriene receptor antagonists (MD=-1.05; 95%CI=-1.33;-0.77). Intranasal antihistamines were more effective than oral antihistamines at improving the TNSS (MD=-0.47; 95%CI=-0.81;-0.14; I2=0%) and RQLQ (MD=-0.31; 95%CI=-0.56;-0.06; I2=0%). Conclusions Randomized controlled trials suggest that intranasal treatments are more effective than oral treatments at improving symptoms and quality of life in seasonal allergic rhinitis.