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BACKGROUND In cystic fibrosis, observation of a lung function drop (as percent predicted forced expiratory volume in 1 s [FEV1 ]; ppFEV1 ) frequently precedes pulmonary exacerbation (PEx) diagnosis. Recovery of ppFEV1 to a previous "baseline" is commonly used to assess antimicrobial treatment response. However, not all diagnosed PEx are associated with a ppFEV1 drop, and it is unclear whether these are a different type of PEx from those associated with a ppFEV1 drop. METHODS We analyzed pre- and posttreatment ppFEV1 for PEx recorded in the Epidemiologic Study of Cystic Fibrosis from 2003 through 2005. Baseline, pretreatment, and follow-up ppFEV1 were the best recorded within 12-months pre-PEx, the lowest recorded -30 to +3 days of treatment, and the best recorded during 6-month follow-up, respectively. Logistic regression models for return of ppFEV1 to baseline during follow-up were developed separately for PEx with ≥10%

Objectives The Global Lung Function Initiative (GLI, 2012) developed reference equations for forced expiratory volume in 1 s (FEV1). Previous equations were developed by groups led by Knudson (1983), Wang (1993), Hankinson (1999), and Stanojevic (2008).1,2,4,6 We assessed how different prediction equations affect the conclusions from a therapeutic intervention study that evaluated the rate of percent predicted FEV1 (ppFEV1) decline. Methodology Using data from the Epidemiologic Study of cystic fibrosis (CF), we re-analyzed our previous study evaluating the relationship of dornase alfa (DA) use with ppFEV1 using the Knudson, Wang & Hankinson, Stanojevic, and GLI equations. The change in intercept and change in slope of ppFEV1 from a 2-year pre-index period and 2-year post-index period were compared between the treated (N = 2483) and comparator groups (N = 6992, from 4110 unique patients). Results Change in intercept for the comparator group was similar across equations except that Wang & Hankinson values were more negative. The difference in change in intercept between the DA and comparator groups ranged from 3.38 to 4.02% predicted. The change in slope for the comparator group ranged from −0.58 to +0.30 ppFEV1/year, but the difference in change in slope between the DA and comparator groups was in a narrower range from +0.53 to +0.89 ppFEV1/year. Conclusions Although individual patient results are impacted by the choice of reference equations, the study conclusions from this evaluation of a therapeutic intervention were minimally affected. GLI equations are recommended for future studies, but prior results based on other equations should be accepted as reliable.

Background When the chronic respiratory therapy dornase alfa was made commercially available for cystic fibrosis (CF) more than 20 years ago, two regimens were approved: 2.5 mg inhaled once daily (QD) or twice daily (BID). In the intervening years, there has been little guidance as to when to use each regimen. We have studied clinical practice patterns captured in the Epidemiologic Study of CF (ESCF) during the decade following dornase alfa approval (1994-2005) to better understand clinical characteristics associated with QD versus BID dornase alfa use. Methods We studied the characteristics of ESCF patients who received either dornase alfa regimen for at least 12 months and who were then switched to the alternate regimen for at least 6 months and who had adequate data available around the time of the switch. Average lung function and weight-for-age (WFA) z-scores, numbers of intravenous (IV) antibiotic-treated pulmonary exacerbations, and prevalence of signs and symptoms were determined for 6-month periods capturing the beginning (FIRST) and the end (LAST) of the initial regimen, the 6 months preceding the final 6 months of the initial regimen (PRIOR), and the beginning of the second regimen (POST). Changes in values from FIRST to LAST, PRIOR to LAST, and LAST to POST were studied to better understand clinical scenarios associated with decisions to change regimens. Results A total of 1342 QD and 574 BID regimens were studied with median durations of 3.19 and 2.09 years, respectively. On average, patients beginning BID regimens had worse lung function and a greater number of pulmonary exacerbations treated with IV antibiotics than those beginning QD regimens. However, by the time of regimen switch, patients switching from QD to BID dornase alfa had experienced substantial deterioration with respect to pulmonary exacerbations and signs and symptoms, whereas patients switching from BID to QD had not. Interestingly, incidence of IV-treated pulmonary exacerbations and signs and symptom prevalence decreased for both populations after regimen switch. Conclusions We have studied populations of patients with CF receiving dornase alfa who were switched between regimens to characterize clinical course. Our results suggest that the most common clinical attribute associated with switching from QD to BID dornase alfa was a marked deterioration in stability characterized by increased incidence and frequency of pulmonary exacerbation. For this population, deterioration in lung function did not appear to be a driver for this switch. In contrast, patients receiving BID dornase alfa who were ultimately switched to QD appeared to be clinically stable, on average, suggesting that treatment burden and cost may have been drivers of the decision to switch regimens.

The Global Lung Function Initiative (GLI, 2012) developed reference equations for forced expiratory volume in 1 s (FEVUsing data from the Epidemiologic Study of cystic fibrosis (CF), we re-analyzed our previous study evaluating the relationship of dornase alfa (DA) use with ppFEVChange in intercept for the comparator group was similar across equations except that WangHankinson values were more negative. The difference in change in intercept between the DA and comparator groups ranged from 3.38 to 4.02% predicted. The change in slope for the comparator group ranged from -0.58 to +0.30 ppFEVAlthough individual patient results are impacted by the choice of reference equations, the study conclusions from this evaluation of a therapeutic intervention were minimally affected. GLI equations are recommended for future studies, but prior results based on other equations should be accepted as reliable.

SummaryObjective To study the association between wheezing in children with cystic fibrosis (CF) and lung function in later life. Methods We used data from the Epidemiologic Study of CF, a longitudinal observational study from 1994 to 2005. Wheezing phenotypes were defined as: no wheezing in the first 6 years of life (NW), transient wheezing (TW; wheezing

SummaryObjectives Tobramycin inhalation solution (TIS; TOBI®) has improved forced expiratory volume in 1 sec (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. Methods Patients 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

To study the association between wheezing in children with cystic fibrosis (CF) and lung function in later life.We used data from the Epidemiologic Study of CF, a longitudinal observational study from 1994 to 2005. Wheezing phenotypes were defined as: no wheezing in the first 6 years of life (NW), transient wheezing (TW; wheezing3 years old, but no wheezing after 3), late wheezing (LW; wheezing only after age 3 years), and persistent wheezing (PW; wheezing both before and after age 3 years). A linear regression model was developed predicting the best forced expiratory volume in 1 sec (FEV1 ) at age 6 or 7 years (6 to8) for each wheezing phenotype.A total of 1302 children met the cohort inclusion criteria; 61% of the cohort had wheezing in the first 6 years of life. A history of any wheezing in the first 6 years of life was associated with a significantly lower FEV1 at 6 to8 years compared to children with NW. The FEV1 of children with NW at age 6 to8 years was 104% predicted, whereas the mean FEV1 in TW, LW, and PW groups was 98%, 100%, and 96% predicted, respectively (P 0.05 compared to NW).Childhood wheezing in CF is common and is associated with lower lung function at age 6 to8 years. Our results identify a clinical feature in early childhood CF associated with lower lung function in later life.

Tobramycin inhalation solution (TIS; TOBI®) has improved forced expiratory volume in 1 sec (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.Patients 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 TIS10% 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.During 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).Initiating 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.