Intranasal antihistamines and corticosteroids in allergic rhinitis: A systematic review and meta-analysis

There is insufficient systematised evidence on the effectiveness of individual intranasal medications in allergic rhinitis (AR).To perform a systematic review to compare the efficacy of individual intranasal corticosteroids and antihistamines against placebo in improving the nasal and ocular symptoms and the rhinoconjunctivitis-related quality-of-life of patients with perennial or seasonal AR.We searched four electronic bibliographic databases and three clinical trials databases for randomised controlled trials (i) assessing adult patients with seasonal or perennial AR and (ii) comparing the use of intranasal corticosteroids or antihistamines versus placebo. Assessed outcomes included the Total Nasal Symptom Score (TNSS), the Total Ocular Symptom Score (TOSS) and the Rhinoconjunctivitis Quality-of-Life Questionnaire (RQLQ). We performed random-effects meta-analyses of mean differences for each medication and outcome. We assessed evidence certainty using the GRADE approach.We included 151 primary studies, most of which assessed patients with seasonal AR and displayed unclear or high risk of bias. Both in perennial and seasonal AR, most assessed treatments were more effective than placebo. In seasonal AR, azelastine-fluticasone, fluticasone furoate and fluticasone propionate were the medications with the highest probability of resulting in moderate or large improvements in the TNSS and RQLQ. Azelastine-fluticasone displayed the highest probability of resulting in moderate or large improvements of TOSS. Overall, evidence certainty was considered "high" in 6/46 analyses, "moderate" in 23/46 analyses, and "low"/"very low" in 17/46 analyses.Most intranasal medications are effective in improving rhinitis symptoms and quality-of-life. However, there are relevant differences in the associated evidence certainty.