Persistent allergic rhinitis has a moderate impact on the sense of smell, depending on both nasal congestion and inflammation

Abstract

A degree of smell disturbance has been found in seasonal and perennial allergic rhinitis, but alterations in olfaction in patients with persistent allergic rhinitis (PER) have not yet been evaluated. The aims of the study were to evaluate the impact of PER on the sense of smell, and to characterize this impact based on self-reported hyposmia (SRH) and PER severity. A prospective controlled study was performed on 49 consecutive patients with PER. PER patients were subclassified depending on severity and the presence of SRH. Olfactory function was evaluated by the Barcelona Smell Test-24 (BAST-24) olfactometry for smell detection, identification, and forced choice for first and fifth cranial nerve (CN) dependent odors in comparison to a group of 60 healthy volunteers. In patients with SRH, obstruction was evaluated by peak nasal inspiratory flow (PNIF) and acoustic rhinometry; and nasal inflammation was evaluated by nasal nitric oxide (nNO). Most patients with PER (67%) presented SRH. Moderate/severe PER (84.8%) predominated among patients with SRH, while mild PER (75%) predominated among patients without SRH. Smell detection, identification, and forced choice tests were significantly worse in PER patients (P < .05) than in healthy controls for the odors related to the first and fifth CN. Among subgroups, patients with moderate/severe PER and/or with SRH presented a significant reduction in smell detection (P < .05) compared to healthy controls. Nasal NO correlated (R: 0.4; P < .05) with loss of smell. Patients with PER have a moderate loss of smell (BAST-24) with a higher impairment in those with self-reported hyposmia and moderate-to-severe PER. These results suggest that the sense of smell should be further investigated in all patients with allergic rhinitis, both in a clinical setting and in clinical trials.