Baseline reticular basement membrane morphology is related to subsequent spirometry deterioration in pediatric chronic airway inflammation: A follow-up study.

Reticular basement membrane (RBM) thickening may occur in children with allergic bronchial asthma (BA), cystic fibrosis (CF), and primary ciliary dyskinesia (PCD). Its functional consequences remain unknown. We investigated the relationship between baseline RBM thickness and subsequent spirometry. In our cohort follow-up study, patients aged 3-18 years with BA, CF, and PCD and controls underwent baseline lung clearance index (LCI) measurement, spirometry, and endobronchial biopsy sampling. Total RBM and collagen IV-positive layer thickness were measured. Trends in forced vital capacity (FVC), forced expired volume in 1 second (FEV1 ), and FEV1 /FVC were analyzed during follow-up, and their relationship to baseline characteristics was studied using univariate analysis and multiple regression models. Complete baseline data were available in 19 BA, 30 CF, 25 PCD patients, and 19 controls. The RBM was thicker in BA (6.33±1.22 μm), CF (5.60±1.39 μm), and PCD (6.50±1.87 μm) than in controls (3.29±0.55 μm) (all p<0.001). The LCI was higher in CF (15.32±4.58, p<0.001) and PCD (10.97±2.46, p=0.002) than in controls (7.44±0.43). The median follow-up times were 3.6, 4.8, 5.7, and 1.9 years in BA, CF, PCD, and controls respectively. The Z-scores of FEV1 and FEV1 /FVC deteriorated significantly in all groups except in controls. In CF and PCD, trends in FEV1 z-scores correlated with baseline LCI and RBM; in BA, it correlated with collagen IV. In multiple regression models, RBM morphology and ventilation inhomogeneity could predict up to 84.4% of variability in spirometry trends. In conclusion, baseline LCI value and RBM morphology may predict trends in subsequent spirometry.