Changes in Lung Function Based on Differences in Spirometry Equipment Used in Children With Cystic Fibrosis

The investigators' Upstate Cystic fibrosis (CF) Care Center is very active in research. For example, in 2009, 68 of our 135 pediatric patients have been participating in 16 clinical trials. Sponsors often provide their study sites with spirometers to use for PFTs. These machines are meant to provide uniform PFTs results for studies, which include measurement of FEV1 values. In 2009, among the 52 patients at our Center who are 6-12 years old, 20 (38%) have been in studies with sponsor-provided spirometers. Among the 32 patients ages 13-17 years, 13 (40%) have been in studies with sponsor-provided spirometers. Anecdotally, the investigators have noted that FEV1 results obtained during clinical trials for our patients appear to be lower than those of our patients' usual values, especially with younger children. The investigators hypothesize that the apparent difference in PFT results might be related to the different incentives (if any) provided by study PFT equipment. Further, if this difference exists, the investigators believe that this may account for the apparent average decline in the lung function results of our patients over the recent years, given the large proportion of our patients who participate in clinical trials. Finally, the investigators hypothesize that younger children may be more affected by the difference in incentives than older ones. The purpose of this study is to collect an additional set of Pulmonary Function Tests (PFTs) using our regular clinic equipment, on all study subjects following their study PFTs if these are done with sponsor-provided equipment. The investigators will compare the results from both types of machines and report regarding differences identified.