Acute Cellular Rejection Is a Risk Factor for Bronchiolitis Obliterans Syndrome Independent of Post-transplant Baseline FEV1

Background: Post-transplant baseline forced expiratory volume in 1 second (FEV1) constitutes a systematic bias in analyses of bronchiolitis obliterans syndrome (BOS). This retrospective study evaluates risk factors for BOS adjusting for the confounding of post-transplant baseline FEV1. Methods: A multivariate survival and competing risk analysis of a large consecutive series of patients (n = 389) from a national center 1992 to 2004. Exclusion criteria were patients not surviving at least 3 months after transplantation (n = 39) and no available lung function measurements (n = 4). Results: The first maximum FEV1 occurred at a median 183 days post-transplant. Freedom from BOS was 81%, 53%, 38% and 15%, and cumulative incidence of BOS was 18%, 43%, 57% and 77% at 1, 3, 5 and 10 years post-transplantation, respectively. Acute cellular rejection was independently associated with an increased cause-specific hazard of BOS (hazard ratio 1.4, confidence interval 1.1 to 1.8, p = 0.009). The absolute value of baseline FEV1 was a significant confounder in all survival and competing risk analyses of BOS (p < 0.05). Conclusion: Despite early diagnosis and prompt treatment, acute cellular rejection remains an independent risk factor for the development of BOS after adjusting for the confounding of post-transplant baseline FEV1. [Copyright &y& Elsevier]