The prognosis of BOS according to the slope of FEV1 change during the first 3 months after BOS diagnosis
When death or lung TPL was defined as an event, the median pre-event period 13.5 months (IQR, 8.4-30.9 months) for Group 1 after BOS diagnosis, and the observation period for Group 2 was 59.7 months (IQR, 43.0-85.6 months). When O2 therapy was defined as an event, 10.2 months (IQR, 5.8-17.9 months) for Group 3, and the observation period for Group 4 was 59.8 months (IQR, 33.9-102.0 months).
When comparing the Kaplan-Meier estimates between groups with positive and negative slopes of FEV1 change during the first 3 months after BOS diagnosis, the group with a negative slope had a higher likelihood of being Group 1 with a marginal significance when compared to the group with a positive slope (P =0.057 according to the log-rank test) (Figure 2a). Also, the group with a negative slope of FEV1 change during the first 3 months after BOS diagnosis had a significantly higher probability of being Group 3 when compared to the group with a positive slope (P =0.014 according to the log-rank test) (Figure 2b).