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1. Do Disease-Specific Reference Values for FEV1 in Cystic Fibrosis Convey Unique Information?M. Qureshi, MD, R. Consunji-Araneta, MD, and H. Pasterkamp, MD, FRCPCDepartment of Pediatrics,University of Manitoba, Winnipeg, MB, Canada E4/325 Introduction Summary Abstract Subjects Spirometric measurements are typically expressed as % predicted normal (% pred.), based on reference data from a sample of healthy subjects. Recently, disease specific reference values for FEV1 (CF-FEV1) were reported for Cystic Fibrosis (AJRCCM 2005;172: 885-91). To test whether CF-FEV1 provides information that is not evident from pulm-onary function tests (PFTs) expressed as %pred. we reviewed data collected at the Winnipeg Children's Hospital. Between 1994 and 2004, 81 CF patients had tests of static and dynamic lung function. Excluding their first year of tests to reduce variab-ility and also excluding PFTs during respiratory exacerbations there were 61 CF patients (28 female) who had at least four measurements. We compared CF-FEV1 by age (6-10 y, 11-15 y, and 16-20 y) and over time against FEV1, forced vital capac-ity, maximum midexpirat-ory flow, residual volume, total lung capacity, and also against height and weight (z-scores). ANOVA and linear regression analysis was applied and Tukey’s test was used for post hoc analysis. Significance was accepted at p < 0.05. The average FEV1 %pred. in the three age groups was 85% ± 1.3 (S.E.), 71% ± 0.9 and 74% ± 1.4, resp-ectively. This corresp-onded to CF-FEV1 of 49% ± 1.9, 48% ± 1.4 and 46% ± 1.9. The overall rate of decline in FEV1 %pred. was -2.2% ± 0.9 per year while the mean rate of decline in CF-FEV1 was -1.7% ± 0.9 per year. Thirteen of the 61 patients showed an annual decline in CF-FEV1 >5%. In 10 patients there was a >5% per year increase in CF-FEV1. Only few patients who declined in CF-FEV1 would not have been readily identified on PFTs expressed as % pred. Patients who improved over time in CF-FEV1 were closer to normal in height (-0.36±0.13) and weight (-0.15±0.04) than those who declined (-0.54 ± 0.06 and -0.73 ± 0.08, respectively). However, there was no correlation between the decline in CF-FEV1 and the rate of change in growth para-meters. In a few cases, expressing FEV1 relative to CF-FEV1 may provide information that is not apparent when PFTs are referenced to general population norms. Nevertheless, the opport-unity to compare our patients’ lung function against the 287,108 FEV1 observations among more than 21,000 patients in the American CF Foundation National Patient Registry only strengthens our efforts to maximize the potential for each of our patients. • Forced Expiratory Volume in one second (FEV1) is an important measure of pulmonary disease severity in patients with Cystic Fibrosis (CF). • Recently, CF-specific percentiles of FEV1 (CF-FEV1) as a function of height, age and sex were developed[1] to • allow an individual patient’s lung function to be placed in the context of the average lung function for patients with CF of a given sex, age, and height • overcome the limitations of comparing patients with CF to a reference population that has very different distribution of height-for-age; and • describe lung function in terms of percentiles Between 1994 and 2004, the average FEV1 of the pediatric CF population in Manitoba was close to the average of CF-FEV1 established in the U.S. It is of concern that 13 of our 61 patients showed an annual decline of greater than 5% in CF-FEV1. Few patients showed a rate of decline in FEV1 on the CF-FEV1 %iles that was not also apparent on PFTs expressed as % of predicted normal. Patients who improved over time on the CF-FEV1 %iles were closer to normal in height and weight but overall there was no correlation between the decline in lung function and the rate of change in growth parameters. Results Conclusion FEV1 %predicted CF-FEV1 In a few cases, expressing FEV1 relative to disease specific percentiles may provide inform-ation on pulmonary function in children with Cystic Fibrosis that is not evident from FEV1 as % of predicted norm or from other pulmonary function measure-ments. The opportunity to compare our patients’ lung function against the 287,108 FEV1 observations among more than 21,000 patients in the American CF Foundation National Patient Registry only strengthens our efforts to maximize the potential for each of our patients. Methods • Review PFT database at the WCH (1994-2004) • Extract all patients with confirmed diagnosis of CF (sweat chlorid-ometry ± genetics) • Exclude PFTs not done during routine visits • Include only patients with at least 4 PFTs after the first year of tests in the body plethysmograph in order to allow for training • List all measurements of FEV1, FVC, MMEF, RV and TLC • FVC= forced vital capacity • MMEF=maximum midexpiratory flow • RV = residual volume • TLC = total lung capacity • Express all FEV1 measure-ments relative to CF-FEV1 and as % predicted normal (Morris) [2] • Statistical analysis, overall and grouped by age (demographic, descriptive, analysis of differences and ANOVA, correlation analyses) Growth parameters Pulmonary function • References • Kulich M., Rosenfeld M., Campbell J., Kronmal R., Gibson R. L., Goss C. H, and. Ramsay B. 2005. Disease-specific reference equations for lung function in patients with Cystic Fibrosis. Am J Respir Crit Care Med. Vol. 172. pp 885-891 • Morris, J.F. 1976 Spirometry in the evaluation of pulmonary funct-ion. West J. Med. Vol. 125. pp 110-118 • Rosenbluth, D.B., K. Wilson, T. Ferkol, and D.P. Schuster. 2004. Lung function decline in • cystic fibrosis patients and timing for lung transplantation referral. Chest Vol. 126. pp 412-419. Correlation of annual changes in lung function This study was supported by the Manitoba Institute of Child Health