Comparison of lung function during the study period according to the prognosis
Twenty-one subjects repeated PFTs regularly for 24 months after BOS occurred. Among them, nine children did not complete PFTs because they are died or underwent lung TPL within 24 months after BOS diagnosis. The events were defined as death or lung TPL, and O2therapy. The median pre-event period for PFTs in all subjects was 24.0 months (interquartile range [IQR] 7.5-24.0 months) (E-table 1).
Figure 1 illustrates the comparison of lung function during the study period between Group 1 versus Group 2 and Group 3 versus Group 4. FEV1% pred, FVC%, pred, and FEF25-75% pred were lower in Group 1 than in Group 2 at all time points after BOS diagnosis. However, these differences were significant at only the 6, 9, and 18 month time points for FEV1% pred and the 9 month time point for FEF25-75% pred after BOS diagnosis (allP <0.05, Figure 1a, E-table 3a). When comparing Groups 3 and 4, FEV1% pred and FVC% pred were significantly lower in Group 3 than in Group 4 at 3 months post-BOS diagnosis and afterward. The levels of FEF25-75% pred were also significantly lower in Group 3 than in Group 4 at 3, 6, 9, 15, 18, and 21 months after BOS diagnosis (all P <0.05, Figure 1b, E-table 3b).