3.1 Patient Characteristics
The demographic and clinical characteristics of the patients are presented in Table 1. A total of 81 patients, including 30 controls and 51 BO patients, were included in this study. Spirometry and body plethysmography, respectively, were performed on 62 (76.5%) and 56 (69.1%) patients; those who failed PFTs were either too young or were unable to do forced inhalation and exhalation due to severe BO.
Of the 51 BO patients, 44 (86.3%) had previously received HSCT, and 7 post-infectious BO patients (13.7%) were included. The mean age of the control and BO groups was 11.4 and 12.7 years, respectively. In the PFTs, FVC, FEV1, FEV1/FVC, FEF25-75%, RV, DLCO, VA, sRaw, and sGaw were statistically significantly worse in the BO group. Raw% (83.4 ± 36.6 vs. 263.6 ± 234.1; p = 0.006) and sRaw% (114.1 ± 46.4 vs. 463.1 ± 488.2; p = 0.008) were significantly higher. Among the MLD parameters, EXP MLD, MLDD, E/I Volume, E/I MLD, E900, E850, E650, and E600 were all statistically significantly worse in the BO group (Table 1, Figure 2). Expiratory MLD was significantly lower in BO (-731.4 ± 69.6) than in the control group (-659.0 ± 61.6; p < 0.001). In the BO group, the expiratory LAA, E900 (7.7 ± 11.3 vs. 0.4 ± 1.0) and E850 (22.6 ± 21.6 vs. 3.9 ± 9.7) were significantly higher than in the control group, and the HAA, E650 (10.9 ± 7.5 vs. 20.7 ± 10.2) and E600 (13.8 ± 9.2 vs. 26.2 ± 13.8) were statistically significantly lower (all p values < 0.001). There was no significant difference in the above indicators during inspiration.