SEASONAL ONSET OF BRONCHIOLITIS OBLITERANS SYNDROME IN LUNG-TRANSPLANT RECIPIENTS

Background: Bronchiolitis obliterans syndrome is the major complicatio n in long-term survival of patients with lung transplants. Bronchiolit is obliterans syndrome is thought to represent a form of chronic allog raft rejection and is associated with obstructive airways disease. Vir al infections or other exogenous factors may trigger this condition. M ethods: Because respiratory viral infections show seasonal clustering we studied seasonal onset of bronchiolitis obliterans syndrome in 157 lung and heart-lung transplant recipients. Individual baseline values of forced expiratory volume in 1 second were evaluated according to th e International Society for Heart and Lung Transplantation criteria. F or bronchiolitis obliterans syndrome classification, values of forced expiratory volume in 1 second were determined by the average of two me asurements made at least 1 month apart. Onset of bronchiolitis obliter ans syndrome was defined as the date of the initial pulmonary function test showing a persistent decline of forced expiratory volume in 1 se cond. Other factors causing obstructive airways disease were excluded. Results: Forty-nine patients (31%) showed development of bronchioliti s obliterans syndrome (n = 10 stage I, n = 13 stage II, n = 26 stage I II) with onset of bronchiolitis obliterans syndrome 507 +/- 372 days ( mean +/- standard deviation) after transplantation. Baseline value of forced expiratory volume in 1 second was reached at 270 +/- 231 days. Between January and March of each year onset of bronchiolitis oblitera ns syndrome developed in 23 patients (47%). In the second (April to Ju ne) and third (July to September) quarters a persistent decline of pul monary function test results developed in 13 (27%) and 12 (24%) patien ts, respectively, whereas only 1 patient (2%) showed deterioration bet ween October and December (p < 0.001). Conclusions: Seasonal clusterin g of onset of bronchiolitis obliterans syndrome might thus indicate un derlying unknown infectious triggers.