Objective: Chronic rhinitis (CR) is one of the most common conditions globally. CR, nasal polyp (NP), and asthma share similar histopathological features, including marked eosinophil, mast cell, and CD4+ T cell infiltration in both the upper and lower airways. The aim of this study is to investigate the Pulmonary Function Tests (PFTs ) results of patients with a diagnosis of rhinitis and to identify the factors influencing these results.

Materials and Methods: As a cross-sectional study, 1500 patients with CR who presented to a single Immunology and Allergy Diseases outpatient clinic between July 2023 and December 2024 were screened. Demographic and clinical data, skin prick tests and serum specific Immunoglobulin E (IgE) results, PFTs, and laboratory findings were retrospectively analysed.

Results: A total of 130 patients met the inclusion criteria. Of these, 59.2% were female (n=77) and 40.8% male (n=53). Patients in the AR group were significantly younger than those in the NAR group. In addition, compared to the NAR group, the lymphocyte and eosinophil counts as well as the total IgE levels were found to be significantly higher in the AR group. NPs were significantly more common in the NAR group. In eosinophilic patients, both Forced Expiratory Volume in one second (FEV1) % and Maximal Expiratory Flow (MEF25- 75) % values were significantly lower than in non-eosinophilic patients. Similarly, patients with NPs had significantly lower Forced Expiratory Volume in one second / Forced Vital Capacity (FEV1/FVC) % and MEF25-75% values compared to those without NPs. No significant correlation was found between allergen sensitisation and PFTs parameters. However, a moderate negative correlation was observed between eosinophilia and both MEF 25-75% and FEV1%. Additionally, a weak negative correlation was found between the presence of NPs and both MEF 25-75% and FEV1/FVC%.

Conclusion: In patients with CR, elevated peripheral blood eosinophil counts and the presence of NPs may be important predisposing factors for lower airway obstruction.