PURPOSE: Chronic rejection, defined as a decrease in forced expiratory volume in one second (FEV1) of 20%, is the main cause of late mortality after lung transplantation. Evidence of small airway obstruction, manifested by scooping on flow volume loops, may be predictive of progression to chronic rejection.
METHODS: Forced expiratory flow at half vital capacity (FEF50) to maximal forced expiratory flow (FEFmax) ratio is a measure of scooping. FEF50/FEFmax prior to and at start of decline of FEV1 in 30 lung transplant patients with chronic rejection were measured and compared to best post-operative and a value prior to onset of chronic rejection. Four hypotheses were tested as predictors of progression to chronic rejection: #1 a decline in FEF50/FEFmax of greater than or equal to 10% from best post-operative PFT to the PFT prior to decline of FEV1; #2 a decline in FEF50/FEFmax of greater than or equal to 10% from best post-operative PFT to the PFT at the start of decline; #3 FEF50/FEFmax ratio prior to decline less than 40%; #4 FEF50/FEFmax ratio at start of decline less than 40%.
RESULTS: Thirty patients met criteria for chronic rejection. Nineteen of 30 had a decline in FEF50/FEFmax greater than 10% from best post-operative PFT to prior to decline (sensitivity 0.633). Nineteen of 29 had a decline greater than 10% from best post-operative PFT to start of decline (sensitivity 0.655). Fifteen of 30 had FEF50/FEFmax less than 40% prior to decline (sensitivity 0.5). Eighteen of 29 had FEF50/FEFmax less than 40% at the start of decline (sensitivity 0.621). Specificity for all tests was 0.619. Combination criteria and ratios measured between the initial decline and the PFT meeting the criteria for rejection are being examined.
CONCLUSION: With sensitivities and specificities in the 60 percent range, the PFT parameters individually were not accurate tests for predicting progression to chronic rejection.
CLINICAL IMPLICATIONS: Early detection of progression to chronic rejection may permit early intervention and modify outcome.
DISCLOSURE: Nancy Porhownik, None.