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Background Preserved Ratio Impaired Spirometry (PRISm) is defined by reduced forced expiratory volume in one second (FEV 1) with a preserved FEV1/FVC ratio. It is associated with increased morbidity and may represent an intermediate stage in the development of chronic respiratory disease. Small airway dysfunction (SAD) contributes to conditions such as COPD, asthma, and idiopathic pulmonary fibrosis.Aim To examine the association between PRISm and SAD in an Irish adult population.Methods A cross-sectional study was conducted at the Respiratory Department, Connolly Hospital, Dublin. Spirometry results from patients were retrospectively reviewed. Data included demographics, clinical history, and post-bronchodilator spirometry. PRISm was defined as FEV 1/FVC ≥ 0.70 with FEV1 < 80% predicted. SAD was diagnosed when at least two of MMEF, FEF5 0, and FEF7 5 were <65% predicted.Results Over five years, 962 (24.2%) met PRISm criteria. Of these, 51.4% were male (p = 0.044). PRISm patients were significantly older (p = 0.001). Although more common in Caucasians, this was not significant (p = 0.125). Most were overweight or obese (p = 0.689, not significant). Mean FEV 1 was significantly reduced in PRISm (p < 0.001). MMEF7 5–2 5 was significantly lower (p = 0.040), with marginal reductions in FEF5 0 and FEF7 5 (p = 0.093, p = 0.058).Conclusion PRISm is a prevalent spirometric pattern in Irish adults and shows a significant association with SAD, supporting its recognition as a distinct early airway disease phenotype.