Inflammatory markers associated with chronic obstructive pulmonary disease (COPD) were linked to increased symptom burden, a greater number of exacerbations, and decreased 6-minute walk distance in smokers with preserved spirometry, according to the study results published in CHEST.
Whole blood samples from smokers with preserved spirometry who were enrolled in SPIROMICS, a longitudinal prospective cohort study, were used to determine levels of C-reactive protein (CRP), fibrinogen, and the soluble tumor necrosis factor (TNF) receptors 1A and 1B. Associations were then examined between these inflammation markers and symptom burden, self-reported exacerbations, and 6-minute walk distance. Exacerbations were defined as the use of antibiotics, systemic glucocorticoids, and/or a healthcare utilization event.
Of the 830 smokers without airflow limitation, 415 were symptomatic. CRP was associated with worse symptoms, with median levels of 3.6 μg/mL in symptomatic participants compared with 2.0 μg/mL in participants without symptoms (P <.001). Furthermore, CRP and blood neutrophil count were associated with increased odds of having chronic bronchitis. In addition, CRP was associated with retrospective exacerbations. When examining functional ability, both CRP and soluble TNF receptors 1A were negatively correlated with 6-minute walk distance.
“The relative contribution of systemic versus type 2 inflammation to disease burden among smokers with preserved spirometry remains uncertain,” the researchers wrote. “We demonstrate that markers of systemic inflammation, including CRP and [soluble TNF receptors 1A] are associated with respiratory symptoms, exacerbations, and activity limitation amongst ever smokers who do not meet the current spirometric definition of COPD.”
Disclosures: Several authors report financial relationships with pharmaceutical companies. For a full list of disclosures, please visit the reference.
Garudadri S, Woodruff P, Han M, et al. Systemic markers of inflammation in smokers with symptoms despite preserved spirometry in SPIROMICS [published January 23, 2019]. CHEST. doi:10.1016/j.chest.2018.12.022