Introduction: Among risk factors for the progression of bronchiolitis obliterans syndrome (BOS) after lung transplantation (LT), the influence of time to BOS onset is not known. The aim of the study was to assess if BOS occurring earlier after LT is associated with worse functional prognosis and worse graft survival.
Method: We retrospectively compared functional outcome and survival of all single-LT (SLT) recipients who had BOS develop during follow-up in our center according to time to onset of BOS (< 3 years or ≥ 3 years after transplantation).
Results: Among the 29 SLT recipients with BOS identified during the study period, 20 patients had early-onset BOS and 9 patients had late-onset BOS. The mean decline of FEV1 over time during the first 9 months in patients with early-onset BOS was significantly greater than in patients with of late-onset BOS (p = 0.04). At last follow-up, patients with early-onset BOS had a lower mean FEV1 value (25% vs 39% of predicted, p = 0.004), a lower mean Pao2 value (54 mm Hg vs 73 mm Hg, p = 0.0005), a lower 6-min walk test distance (241 m vs 414 m, p = 0.001), a higher Medical Research Council index value (3.6 vs 1.6, p = 0.0001), and a higher percentage of oxygen dependency (90% vs 11%, p = 0.001) compared with patients with late-onset BOS. In addition, graft survival of patients with early-onset BOS was significantly lower than that of patients with late-onset BOS (log-rank test, p = 0.04). There were 18 of 20 graft failures (90%) in the early-onset BOS group, directly attributable to BOS in all cases (deaths [n = 10] or retransplantation [n = 8]). In the late-onset BOS group, graft failure occurred in four of nine patients due to death from extrapulmonary causes in three of four cases. The median duration of follow-up after occurrence of BOS was not statistically different between patients with early-onset BOS and patients with late-onset BOS (31 ± 28 months and 37 ± 26 months, respectively; p = not significant).
Conclusion: The subgroup of patients who had BOS develop ≥ 3 years after SLT are less likely to have worrisome functional impairment develop in long-term follow-up. Considering the balance between the advantages and risks, enhancement of immunosuppression should be regarded with more caution in this subgroup than in patients with early-onset BOS.