Abnormal spirometry in individuals with a smoking history and no known obstructive lung disease: current understanding and clinical implications.

Purpose of Review: Recent recognition of the importance of abnormal spirometry without obstruction has generated interest in its epidemiology, risk factors, longitudinal outcomes, and clinical implications.
Recent Findings: Preserved ratio impaired spirometry (PRISm), defined as an forced expiratory volume in 1 s (FEV 1 )/ forced vital capacity (FVC) ≥0.7 with an FEV 1 <80% predicted, has a high prevalence globally (2.4-16.7%) and is more common in individuals with metabolic comorbidities, smoking history, female sex, and higher BMI. PRISm is associated with increased respiratory symptoms and poor clinical outcomes such as increased all-cause mortality and cardiovascular events compared to normal spirometry. Longitudinal studies show substantial subsets of individuals with PRISm will transition to other spirometric categories, including progression to obstruction. Individuals with PRISm are heterogeneous; recent investigations have focused on subtyping PRISm based on spirometric features or pathobiologically-based phenotypes.
Summary: PRISm is a common spirometric abnormality which is robustly associated with negative outcomes. However, current knowledge gaps with respect to heterogeneity, specific etiologies, and longitudinal progression preclude the development of universal evidence-based diagnostic and management strategies. At present, clinicians are advised to focus on risk factor modification (e.g., diabetes, obesity) and the identification of actionable traits (e.g. emphysema, interstitial lung abnormalities) among patients with PRISm.
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