The association between abdominal obesity and pulmonary function trajectories among patients with COPD

The association between abdominal obesity and pulmonary function trajectories among patients with COPD remain to be unclear. This study aimed to explore the association between abdominal obesity and pulmonary function trajectories among patients with COPD. Data were collected from the China Health and Retirement Longitudinal Study, which was a nationally representative investigation. The pulmonary function indicator was peak expiratory flow (PEF). Abdominal obesity was assessed using waist circumference, which was categorized into two groups: < 90/85 cm and ≥ 90/85 cm, in men/women. Latent class growth analysis was used to identify distinct pulmonary function trajectories. The logistic regression was used to assess the association between abdominal obesity and pulmonary function trajectories. Finally, a total of 775 patients with COPD aged 45 years and older were included, and 301 participants (38.84%) were abdominal obesity. The mean PEF value showed a decreasing trend, with respective average values of 205.84 L/min (SD = 104.16), 199.99 L/min (SD = 99.52), and 196.06 L/min (SD = 86.74) in 2011, 2013 and 2015. Two PEF trajectories were identified: "above average-high descending" trajectory (n = 187, 24.13%) and "low-maintenance" trajectory (n = 588, 75.74%). Unadjusted and adjusted analysis showed that baseline higher waist circumference was associated with "low-maintenance" trajectory. A negative association between abdominal obesity and pulmonary function trajectories was observed among patients with COPD. This suggests that increased abdominal fat may accelerate the decline of pulmonary function over time. These findings provide evidence for designing targeted programs to improve pulmonary function, particularly for patients with COPD of abdominal obesity.