Time-related changes in pulmonary function after conversion to tacrolimus in bronchiolitis obliterans syndrome

Background: Bronchiolitis obliterans syndrome (BOS) is a leading cause of morbidity and mortality after lung and heart-lung transplantation. Present treatment is directed at the augmentation of pharmacologic immunosuppression. Methods: This study examines the effect of substituting cyclosporine with tacrolimus on the forced expiratory volume in 1 second (FEV1) and on the forced expiratory flow between 25% and 75% of vital capacity (FEF25%-75%) in 32 patients who. developed BOS. The proportional rates of decline of FEV1 and FEF25%-75% before and after treatment with tacrolimus were calculated. The actuarial survival of responders and non-responders to tacrolimus was compared. Pre-operative and post-operative factors were investigated to determine any difference between the 2 groups. Results: There were significant reductions in the rates of decline of FEV1 and FEF25%-75% when the rates in the 3 months before conversion to tacrolimus were compared with subsequent rates at 0 to 3 months, 3 to 6 months, 6 to 9 months and 9 to 12 months after conversion. The rates of decline of FEV1 and FEF25%-75% in the 3 months before conversion were 0.11 liters/month and 0.13, liters/s per month, respectively. This compares with the rates of decline for FEV1 and FEF25%-75% for the 3 months after conversion to tacrolimus of 0.04 liters/month (p = 0.023) and 0.04 liters/s per month (p = 0.022), respectively. The actuarial survival at 1 year from the time of conversion to tacrolimus for the responder sub-group and the non-responder sub-group were 89.2% and 75%, respectively, and at 4 years after conversion were 61.3% and 56.3%, respectively (p = 0.92). Conclusions: Tacrolimus rescue therapy is effective at stabilizing lung function in patients with BOS, and this effect is apparent up to 12 months after conversion from cyclosporine.