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September 23, 2025Open Access

Canonical correlation analysis on the association between pulmonary function and obesity in early-onset COPD: CT-based body composition analysis

JSJiaru ShiBeijing University of Chinese Medicine TLTianye LiWenzhou Medical University ZCZhenghao ChenHebei University

Key Points

Elevated BMI and visceral adipose tissue are linked with better pulmonary function in early-onset COPD patients, but results vary by metric.
The COPD group showed a moderate correlation (r = 0.383) between body composition and pulmonary function, indicating significant associations.
Structure of study involved analyzing CT-based body composition in both early-onset COPD and non-COPD participants to assess these relationships.
Non-COPD subjects demonstrated a stronger correlation (r = 0.537) and an overall enhancement in respiratory function, differing from the COPD group.

Abstract

Background While body composition impacts pulmonary function, the differential effects of visceral (VAT) vs. subcutaneous adipose tissue (SAT) in early-onset COPD remain unquantified. Objective To elucidate the relationship between obesity patterns and pulmonary function in early-onset COPD versus non-COPD populations, focusing on body mass index (BMI), visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT) distribution. Methods This retrospective cohort study analyzed 290 patients (144 early-onset COPD, 146 non-COPD) aged 20–50 years. Body composition (BMI, SAT, VAT) was quantified via CT at the L1 vertebral level. Pulmonary function was assessed by bronchodilator responsiveness testing (FEV₁/FVC, MEF₇₅, MEF₅₀, MEF₂₅). Canonical correlation analysis (CCA) was used to evaluate the multidimensional associations between body composition and pulmonary function. Results Canonical correlation analysis revealed distinct multidimensional relationships between body composition and pulmonary function across study cohorts ( p 0.05). In the early-onset COPD cohort (N = 144), a statistically significant canonical variate (r = 0.383, λ = 0.172) demonstrated moderate association strength linking body composition (X 1 : BMI, SAT, VAT) with pulmonary function (Y 1 : FEV 1 , FVC, MEF 75 , MEF 25 ). Conversely, the non-COPD group (N = 146) exhibited stronger canonical correlation (r = 0.537, λ = 0.405), with body composition (X 2 : BMI, VAT) associating with pulmonary function (Y 2 : FEV 1 , FVC). Conclusion In summary, early-onset COPD patients with elevated BMI and VAT but reduced SAT exhibited improved pulmonary function across most parameters. This enhancement was not observed in MEF 50 and MEF 25 . In contrast, the non-COPD cohort exhibits overall respiratory enhancement, as the cross-loading coefficient of MEF25—an indicator reflecting the weight of a variable in contributing to the canonical variate—is extremely small (0.05) and has a negligible impact on the overall association.

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