Background: Our aim was to determine the variables influencing sputum rheology in patients with severe asthma, Chronic Obstructive Lung Disease (COPD) and non-CF bronchiectasis (NCFB)
Methods: We performed a cross sectional prospective cohort study. Spontaneous sputum was collected from consecutive patients with muco-obstructive lung diseases. Sputum rheology was assessed using the RheomucoŽ rheometer (Rheonova, Grenoble); the elastic modulus G?, viscous modulus G??, and critical stress threshold ?c were recorded. Chest High-Resolution CT (HRCT) were performed to assess CT mucus score (Dunican EM, et al. J Clin Invest. 2018), as well as spirometry. Patients were pooled for the analysis. Logistic regressions were performed to explain sputum rheology parameters as a function of CT mucus score and Forced Expiratory Volume in one second (FEV1 %pred).
Results: 48 patients were included from January to August 2019. Among them, 10 had asthma, 14 COPD and 24 NCFB. Median FEV1%pred was significantly lower in the COPD group (FEV1 = 28%pred?[22.75-33.25]) compared to the asthma group (FEV1 = 75%pred?[57-78] (P < .001)) and the non-CF bronchiectasis group (FEV1 =55.5%pred [40-79] (P < .001)). For all pooled patients, CT mucus score was correlated only with viscous modulus G?? (r˛?=?.12 p-value= .014). FEV1 was not significantly correlated with any rheology parameters.
Conclusion: CT mucus score is correlated with sputum viscosity, independently of the underlying muco-obstructive lung disease.