The Effects of Smoking and Airway Restriction on Subclinical Atherosclerosis

Chronic obstructive pulmonary disease (COPD) is a chronic disease associated with systemic inflammation that may accelerate the atherosclerotic process. Smoking is a common risk factor for COPD and atherosclerosis. The goal of this study was to investigate the effects of COPD and smoking on carotid intima-media thickness (CIMT), in order to emphasise their importance in terms of subclinical atherosclerosis.

The study involved 208 male patients aged 45-65 years and was designed as a prospective, observational case-control study. Patients were separated into three groups, as follows: Group 1-non-smokers without airway obstruction (control) (n= 70); Group 2-smokers without airway obstruction (n= 70); and Group 3-smokers with airway obstruction(COPD) (n= 68). They were also classified into thickened CIMT (≥0.8mm) and normal CIMT (<0.8mm) groups. Pulmonary function tests (PFT), carotid Doppler ultrasound, and biochemical and haematological tests were applied to all the participants.

CIMT values were markedly increased in the COPD group (1.00 [0.90-1.30] mm), compared to the smoker group without airway obstruction (0.70 [0.58-0.90] mm) and the non-smoker control group (0.60 [0.50-0.70] mm). The factors associated with CIMT were FEV₁/FVC ratio (Exp B 0.0952, p=0.003), age (Exp B 1.082, p<0.001), and cigarette pack-years (Exp B 1.030, p=0.020). In feature importance analysis, the most influential factor on CIMT was the FEV₁/FVC ratio (0.54) indicating COPD, followed by age (0.33) and cigarette pack-years (0.13).

Among the factors influencing CIMT, the impact of a decreased FEV₁/FVC ratio was found to be the highest. Therefore, screening with carotid US should be considered for the early detection of subclinical atherosclerosis in patients with COPD.