Pulmonary Function in Pediatric Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis

Pediatric inflammatory bowel disease (IBD) is increasingly recognized as a systemic disorder with potential pulmonary involvement, although abnormalities are often subclinical and underdiagnosed.

To systematically review and meta-analyze pulmonary function in children with IBD.

PubMed and Scopus were searched from inception to June 30, 2025 for observational studies reporting pulmonary function tests in patients younger than 18 years with Crohn's disease (CD) or ulcerative colitis (UC), using relevant keywords. Data were synthesized qualitatively and, where possible, pooled using random-effects meta-analysis. Study quality was appraised using the NIH quality assessment tools for observational and case-control studies.

Eight studies involving 395 children and adolescents (244 with CD, 151 with UC) were included. Spirometry indices were largely preserved: pooled estimated mean difference (MD) for FEV₁% predicted was -2.9 (95% CI: -6.0 to 0.3; p = 0.08) and for FVC% predicted -0.8 (95% CI: -2.1 to 0.5; p = 0.21). FEV₁/FVC ratios showed no significant differences (MD -0.5, 95% CI: -1.6 to 0.5). Lung volumes were comparable (TLC% predicted MD -0.8, 95% CI: -1.9 to 0.3). The most consistent abnormality, although not statistically significant, was reduced diffusing capacity: DLCO% predicted was lower in IBD patients (MD -5.8, 95% CI: -12.4 to 0.9; p = 0.09). FeNO levels were similar (MD 0.2 ppb, 95% CI: -3.4 to 3.8).

Pediatric IBD is associated with predominantly subclinical pulmonary involvement, with reduced diffusing capacity emerging as the most consistent abnormality despite preserved spirometry. Longitudinal studies are needed to clarify the clinical significance and evolution of these findings.