Methods of Morphological Analysis of the Flow-Volume Curve for the Diagnosis of COPD: A Scoping Review

Spirometry based on the FEV₁/FVC ratio is the standard method for diagnosing COPD, but its reliance on single-point measurements may limit early detection and underuse biomechanical information contained in the full expiratory flow–volume curve. In response, alternative analytical approaches—including slope analysis, areas under the curve, polynomial modeling, and concavity indices—have been proposed, though evidence regarding their performance, usability, and standardization remains fragmented. This scoping review aims to map and describe the available evidence on morphological analysis methods of the expiratory flow–volume curve as complementary or alternative tools for COPD diagnosis. Following PRISMA-ScR and Joanna Briggs Institute guidelines, studies published between 2000 and 2025 involving populations exposed to risk factors such as tobacco or biomass smoke will be identified through searches in biomedical, multidisciplinary, and engineering databases. Independent reviewers will conduct screening and data extraction to collect information on reference standards, diagnostic performance, reproducibility, and technical feasibility of each method. The review is expected to generate a narrative synthesis and classification of existing methodologies, clarifying their mathematical and geometric foundations, relationship with airflow obstruction, and potential for clinical implementation, thereby informing future standardization efforts in spirometric assessment.