Higher plasma cholesterol and low density lipoproteins are associated with increased airway resistance in COPD

Background: COPD is known to be associated with intermittent hypoxia (IH). Recent reports have shown that IH increases free fatty acid in the circulation. We aimed to investigate the association between circulatory lipid levels and airways resistance in COPD patients. Methods: 114 COPD patients, including 72 smoking COPD (S-COPD) (mean age 65±7 years) and 42 nonsmoking COPD (NS-COPD) (mean age 56±6.9 years) were recruited into this study. Impulse oscillometry was performed (Jaeger, Germany) and plasma lipid levels were measured as per the manufacturer's guidelines. We compared lipid profiles and lung functions between the groups by t-test and tested the association between lung function and plasma profile using Spearman's correlation coefficient. Results: We found that plasma cholesterol and low density lipoproteins correlated significantly with overall lung resistance (R5Hz), proximal airway resistance (R20Hz) and distal airway resistance (R5-20Hz) in COPD patients. | Lipid profile | Airway resistance (kPa/L/Sec) | |:---------------------- | ----------------------------- | ------------ | | | R5Hz | R20Hz | R5-20Hz | | Cholesterol (mg/dl) | 0.30 (0.007) | 0.35 (0.001) | 0.21 (0.06) | | LDL (mg/dl) | 0.30 (0.006) | 0.33 (0.002) | 0.23 (0.04) | | Cholesterol/HDL(mg/dl) | 0.28 (0.01) | 0.28 (0.01) | 0.24 (0.03) | | LDL/HDL(mg/dl) | 0.26 (0.02) | 0.26 (0.02) | 0.22 (0.04) | Association (Spearman's rho) between plasma lipid levels and airway resistance in COPD patients Conclusion: Higher plasma cholesterol and low density lipoprotein levels are associated with increased airway resistance in COPD. More studies are required to validate these findings.