Emphysema-Predominant COPD Had a Greater 5-Year Mortality and a Worse Annual Decline in Lung Function Than Airway Obstruction-Predominant COPD or Asthma at Initial Same Degree of Airflow Obstruction

Abstract

Background and Objectives: We studied whether the extent of exertional oxygen desaturation and emphysema could cause greater mortality in COPD and asthma independent of airflow obstruction. Materials and Methods: We performed a 5-year longitudinal observational study in COPD and asthma patients who matched for airflow obstruction severity. All subjects performed a 6-min walk test (6MWT) and high-resolution computed tomography (HRCT) and followed spirometry and oxygen saturation (SpO2) during the 6MWT every 3–6 months. Overall survival was recorded. Cumulative survival curves were performed according to the Kaplan–Meier method and compared with the log-rank test. Results: The COPD group had higher emphysema scores, higher Δinspiratory capacities (ICs) and lower SpO2 during the 6MWT, which showed a greater yearly decline in FEV1 (40.6 mL) and forced vital capacity (FVC) (28 mL) than the asthma group (FEV1, 9.6 mL; FVC, 1.2 mL; p < 0.05). The emphysema-predominant COPD group had an accelerated annual decline in lung function and worse survival. The nadir SpO2 ≤ 80% and a higher emphysema score were the strong risk factors for mortality in COPD patients. Conclusions: The greater structural changes with a higher emphysema score and greater desaturation during the 6MWT in COPD may contribute to worse yearly decline in FEV1 and higher five-year mortality than in asthma patients with a similar airflow obstruction. The lowest SpO2 ≤ 80% during the 6MWT and emphysema-predominant COPD were the strong independent factors for mortality in chronic obstructive airway disease patients.

Decreased serum IL-35 and IL-37 in COPD patients with severe emphysema

“…They found lower FEV 1 , more acute exacerbations and higher mortality risk in emphysemadominant subtype [20] . Lin et a' study also showed that emphysema-predominant COPD had a greater 5year mortality and a worse annual decline in lung function than airway obstruction-predominant COPD [21] . In addition, they showed the gender differences between two groups that more male patients were observed in the emphysema-dominant subtype [20,21] , which was consistent with our ndings.…”

“…Lin et a' study also showed that emphysema-predominant COPD had a greater 5year mortality and a worse annual decline in lung function than airway obstruction-predominant COPD [21] . In addition, they showed the gender differences between two groups that more male patients were observed in the emphysema-dominant subtype [20,21] , which was consistent with our ndings. Our results showed that lower BMI, worse mMRC scale, lower lung function parameters including FEV 1 and FEV 1 /FVC in severe emphysema group compared to non-emphysema and mild-to-moderate emphysema group.…”