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Original Research

Computer quantification of “angle of collapse” on maximum expiratory flow volume curve for diagnosing asthma-COPD overlap syndrome

, , , &
Pages 3015-3022 | Published online: 01 Dec 2016

Figures & data

Figure 1 Example of the measurement of AC.

Notes: (A) The data points and the optimal couple of regression lines of the descending branch of the maximum expiratory flow volume curve. (B) The MSE of each couple of regression lines. The red point represents the couple of regression line with lowest MSE, which was defined as the optimal couple of regression lines.
Abbreviations: AC, angle of collapse; MSE, mean square error.
Figure 1 Example of the measurement of AC.

Table 1 Participants’ characteristics

Table 2 AC of patients with different degree of airflow limitation and EI

Table 3 The comparison between high and low EI patients with airflow limitation

Figure 2 AC of patients with high and low EI.

Notes: (A) Patient with high EI, FEV1.0, % =44.9%, EI =27.8%, AC =122.5°; (B) patient with low EI, FEV1.0, % =44.5%, EI =6%, AC =149.57°.
Abbreviations: AC, angle of collapse; EI, emphysema index; FEV1, forced expiratory volume in 1 second.
Figure 2 AC of patients with high and low EI.

Table 4 Relationship between pulmonary function parameters and emphysema index in univariate correlation analysis

Table 5 Relationship between pulmonary function parameters and emphysema index in multiple regression analysis

Table 6 The AUC of ROC curve of AC and other pulmonary function parameters

Figure 3 The receiver-operating characteristic curve of angle of collapse for diagnosing high emphysema index.

Figure 3 The receiver-operating characteristic curve of angle of collapse for diagnosing high emphysema index.