Background: Treating allergic rhinitis may have a downstream anti-inflammatory effect on the lower airways. We conducted a dose ranging study in asthma and persistent allergic rhinitis to evaluate if intranasal corticosteroids exhibit a sparing effect on the dose of inhaled corticosteroid.
Methods: Twenty five participants were randomized to receive two weeks of 100 microg/day (Low dose) or 500 microg/day (High dose) of inhaled fluticasone propionate both with intranasal placebo; or inhaled fluticasone 100 microg/day with intranasal fluticasone 200 microg/day (Combined) in a double-blind cross-over fashion.
Results: Low dose fluticasone produced a shift of 1.20 doubling-dilutions (95% CI, 0.63, 1.77); Combined fluticasone, 1.79 doubling-dilutions (95% CI, 0.77, 2.80) and high dose fluticasone, 2.01 doubling-dilutions (95% CI, 1.42, 2.61) in methacholine PC(20) from respective baselines. There was a significant difference between high and low doses: 0.82 doubling dilutions (95%CI, 0.12, 1.50) but not between combined and low dose 0.58 doubling dilutions (95% CI, -0.78, 1.95). Combined treatment alone produced improvements in peak nasal inspiratory flow (P < 0.001), rhinitis quality of life (P = 0.004) and nasal NO (P = 0.01); reduced blood eosinophil count (P = 0.03), and serum eosinophil cationic protein (P = 0.02). All treatments significantly improved tidal NO, FEV(1) and asthma quality of life.
Conclusions: High-dose fluticasone was superior to low dose fluticasone for methacholine PC20, demonstrating room for further improvement. Combined treatment was not significantly different from low dose fluticasone and we could not demonstrate a steroid sparing effect on methacholine PC20. Combined treatment alone produced improvements in upper airway outcomes and suppressed systemic inflammation but not adrenal function.
Trial registration: ClinicalTrials.gov NCT00903227.