Clinical Use of Tobramycin Inhalation Solution ( TOBI1) Shows Sustained Improvement in FEV1 in Cystic Fibrosis

ObjectivesTobramycin inhalation solution (TIS; TOBI (R)) has improved forced expiratory volume in 1sec (FEV1) in cystic fibrosis (CF) trials. Using data from the Epidemiologic Study of CF (ESCF), we assessed the change in level and trend of FEV1 % predicted (pred) over a 2-year period associated with initiation of TIS during routine clinical practice. MethodsPatients age 8-38 years and in ESCF for 2 years before treatment with TIS as a chronic therapy were selected if they remained on therapy for 2 years, defined as being on TIS for at least 3 months per year (C-TIS group). Comparator intervals age 8-38 years used TIS <10% of the time. For each interval, we estimated the level and trend (rate of decline) in FEV1 % pred before and after the index using a piecewise linear mixed-effects model adjusted for potential confounders. ResultsDuring the 2-year pre-index period the C-TIS group (n=2,534) had a more rapid decline in FEV1 (-2.49% vs. -1.39% pred/year) and a lower FEV1 at index (62.6% vs. 74.7% pred) than the comparator group (N=17,656 intervals). After starting chronic TIS, the FEV1 trend line over the 2-year post-index period was higher, but the comparator group's FEV1 was essentially unchanged (difference 2.22, P<0.001). Change in slope was not different between groups (0.06, P=0.82). ConclusionsInitiating chronic TIS therapy in the routine clinical care of patients with CF was associated with improvement in FEV1 % pred but no change in rate of decline, which means that this benefit was sustained over the 2 years studied. Pediatr Pulmonol. 2014; 49:529-536. (c) 2013 Wiley Periodicals, Inc.