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Observational Study
. 2021 Nov 17;57(11):1261.
doi: 10.3390/medicina57111261.

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

Chang-Wei Lin  1   2 , Hung-Yu Huang  1   2 , Fu-Tsai Chung  1   2 , Chun-Yu Lo  1   2 , Yu-Chen Huang  1   2 , Ting-Wen Wang  3 , Lan-Yan Yang  4 , Yu-Bin Pan  4 , Kian Fan Chung  5 , Chun-Hua Wang  1   2
Affiliations
Observational Study

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

Chang-Wei Lin et al. Medicina (Kaunas). .

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.

Keywords: 6 min walk test; asthma; chronic obstructive pulmonary disease; desaturation; emphysema; mortality; pulmonary function.

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Conflict of interest statement

All authors have no conflict of interest to disclose.

Figures

Figure 1
Figure 1
Study flow chart. Abbreviations: COPD, chronic obstructive pulmonary disease.
Figure 2
Figure 2
Kaplan–Meier survival curves for matched asthma and COPD cohort for five-year all-cause mortality. The p value is shown.
Figure 3
Figure 3
Modeled forced vital capacity (FVC) decline over time in milliliters (A) or as a percentage of the predicted value (B) in the three groups.
Figure 4
Figure 4
Modeled forced expiratory volume in one second (FEV1) decline over time in milliliters (A) or as a percentage of the predicted value (B) in the three groups.
Figure 5
Figure 5
Kaplan–Meier survival curves for matched asthma and COPD with or without emphysema cohort for five-year all-cause mortality. The p value is shown.
See this image and copyright information in PMC

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