Alterations in pulmonary function in inflammatory bowel disease are frequent and persist during remission

Information on the occurrence and frequency of pulmonary involvement in patients with inflammatory bowel disease (IBD) is inconsistent. The aim of this prospective study was to determine the frequency and type of pulmonary dysfunction in patients with IBD.

Sixty-six patients with IBD (35 with Crohn's disease [CD] and 31 with ulcerative colitis [UC]) and 30 control patients were investigated with respect to the following pulmonary function tests: forced expiratory volume in 1 s (FEV1), inspiratory vital capacity (IVC), Tiffeneau value (FEV1/IVC), and lung CO transfer capacity (D(LCO)). Disease activity in IBD patients was assessed by the CD activity index for CD and the Truelove index for UC, respectively. Smoking habits and medication were documented in every patient.

Fourteen of 36 CD patients (39%) and 14 of 31 UC patients (45%) but only one of the controls exhibited at least one pathological (<80% of predicted value) pulmonary function test. In both CD and UC lung function tests were significantly decreased in comparison to the control group. This could be shown for FEV1 (-14% of predicted value in CD and -17% in UC, p < 0.01), IVC (-10% in CD and -12% in UC, p < 0.05), and DLCO (-20% in CD and -31% in UC, p < 0.01) without significant differences between both disease entities. The impairment of pulmonary function tests was more pronounced in patients with active disease than in those with inactive disease (FEV1, 81.4% vs 93.4% predicted, p < 0.02; IVC, 84.4% vs 93.7%, p < 0.05; DLCO, 80.4% vs 95.8%, ns).

IBD patients show significantly decreased lung function tests in comparison to healthy controls. The impairment in active disease exceeded that during remission.