Pulmonary Function Test Abnormalities in Pediatric Inflammatory Bowel Disease

Background: Pulmonary involvement in adult patients with inflammatory bowel disease (IBD) seems more common than previously appreciated. Its prevalence and development over time in pediatric IBD patients are largely unknown. Objectives: The aim was to study lung function including fraction of exhaled nitric oxide (FeNO) and transfer capacity for carbon monoxide (TLCO) in pediatric IBD patients and to describe the longitudinal development in a subset of patients with lung function abnormalities. Methods: Sixty-six measurements were made in 48 IBD patients (30 patients with Crohn's disease and 18 with ulcerative colitis) and 108 matched controls. Patients with abnormal TLCO or elevated residual volume/total lung capacity (RV/TLC) ratios were invited for a follow-up. Statistical comparisons were made by nonparametric tests and ANOVA. Results: TLCO was decreased in IBD patients [median: 88% predicted (interquartile range, IQR, 22) vs. 99% predicted (IQR 19) in controls]. RV/TLC ratios were mildly elevated in patients with ulcerative colitis [32% (IQR 9) vs. 27% (IQR 8) in controls], and maximum expiratory flows at 50 and 25% of vital capacity were mildly reduced in patients with Crohn's disease. FeNO and disease activity did not correlate with lung function abnormalities. Abnormalities did not consistently persist over a median follow-up period of 34 months. Conclusions: This study supports evidence that variable and fluctuating pulmonary involvement also occurs in pediatric IBD patients. Its clinical significance is unclear.