Fifty-four RCTs were included (n=at least 14,000 adults and 1,580 children).
Seasonal allergic rhinitis (25 RCTs): The greatest median change in TNSS was reported for intranasal steroids compared with all other treatment classes over two weeks at -43.7% (range -24.5% to -50.0%, p<0.001; seven RCTs). Median changes for other treatment classes were -22.2% for nasal antihistamines (eight RCTs), -23.5% for oral antihistamines (11 RCTs) and -15.0% for placebo (14 RCTs) and all had wide and overlapping ranges. Data for LTRAs were not included in the statistical analysis. Trend analysis for individual nasal symptom scores at two weeks indicated that intranasal steroids were superior for all symptoms, with reductions of at least 40%.
Perennial allergic rhinitis (eight RCTs): The median reduction in TNSS over four to six weeks for oral antihistamines was -51.5% (range -23.7% to 62.0%; p<0.05; five RCTs). For intranasal steroids, median reduction in TNSS was -37.3% (range -32.3% to -42.4%; four RCTs) and for placebo median reduction was -24.8% (range -14.4% to -37.2%; six RCTs). There was wide variability and overlap in the ranges.
Some figures and numbers of studies were inconsistent between box plots and tables/text (number of studies indicated in box plots presented here).
Trend analysis for individual symptom scores was not available for perennial allergic rhinitis data.