Bronchiolitis Obliterans Syndrome and Death in Iranian Lung Transplant Recipients: A Bayesian Competing Risks Analysis

BACKGROUND Bronchiolitis obliterans syndrome (BOS) is delayed allograft deterioration after lung transplant (LTX) that is clinically characterized by ≥ 20% decline from the baseline value of forced expiratory volume during the first second (FEV1). BOS is still a major obstacle limiting long-term survival post-LTX. The main aim of this study was to determine the predictors of BOS and death in Iranian LTX recipients. MATERIALS AND METHODS This retrospective cohort study included 44 LTX recipients who survived ≥ 3 months post-LTX at the Masih Daneshvari Hospital, Tehran, Iran from 2000 to 2014. The outcome was time from lung transplantation to BOS and/or death (due to all causes except BOS). We used competing risks analysis to assess the effect of other factors on the cumulative incidence function of BOS and death. We applied a Fine and Gray model with Bayesian approach. RESULTS The recipients' age (Mean ± SD) was 36.7 ± 14.5 yr. 11 (25%) recipients developed BOS as the first event within the first five years post-LTX and 13 (30%) died due to all causes except for BOS. Our results showed that CMV infection was associated with a significant increase in risk of developing BOS [hazard ratio (HR) 1.22 (95% credible set: (1.01, 3.2)] controlling for other variables. Bilateral transplantation [HR (95% credible set): 2.4(1.51, 4.05)] and CMV infection [HR (95% credible set): 2.02 (1.67, 2.55)] were predictors of the mortality risk. CONCLUSION CMV infection was a predictor of BOS risk in the studied patients. Moreover, bilateral transplantation and CMV infection were significant predictors of mortality in the present sample. Multi-center studies with larger sample sizes are required to better study the other risk factors, and the pathophysiologic mechanisms of BOS.