MODERN COURSE OF RECURRENT OBSTRUCTIVE BRONCHITIS IN PRESCHOOL CHILDREN AND THE ROLE OF VITAMIN D STATUS

Abstract

Relevance. Recurrent obstructive bronchitis (ROB) is an inflammatory disease of the bronchi characterized by repeated episodes of inflammation of the mucous and submucosal layers of the bronchial tree, leading to bronchial obstruction due to edema, hypersecretion, and smooth muscle spasm. ROB remains one of the leading causes of pediatric morbidity in preschool-aged children. Objective. To study the clinical features of recurrent obstructive bronchitis (ROBB) in preschoolers and to assess the association between serum 25(OH)D levels and the frequency of exacerbations. Materials and methods. The study included 50 preschool children with ROB. Clinical, laboratory, and instrumental examinations were performed, along with the collection of data on vitamin D intake and environmental factors. Results. Fifty preschool children with recurrent obstructive syndrome were examined. Based on serum vitamin D levels, participants were divided into three groups: Group 1 – children with vitamin D deficiency (n = 15; 30.0%), mean 25(OH)D level 17.6 ± 1.2 ng/mL; Group 2 – children with vitamin D insufficiency (n = 19; 44.0%), mean 24.6 ± 1.2 ng/mL; Group 3 – children with normal vitamin D levels (n = 16; 32.0%), mean 30.6 ± 1.2 ng/mL. The mean age of the participants was 4.2 ± 1.1 years (median — 4.0 years); 28 (56%) were boys and 22 (44%) were girls. A high frequency of exacerbations was observed among children with low vitamin D levels. A statistically significant inverse correlation was found between serum 25(OH)D levels and the number of annual episodes (r = –0.45, p < 0.01). In the group with 25(OH)D < 20 ng/mL, the mean number of exacerbations per year was 5.2 ± 1.3, whereas in those with 25(OH)D ≥ 30 ng/mL it was 3.1 ± 1.1 (p = 0.002).  Vitamin D deficiency may serve as a marker of increased risk for obstructive exacerbations in preschool children. It is recommended to include serum 25(OH)D assessment in clinical practice and to correct deficiency when necessary. Summary. Our study demonstrates that preschoolers with recurrent obstructive bronchitis and low 25(OH)D levels have a higher frequency of obstructive episodes, more severe disease course, and increased hospitalization rates. These findings suggest that vitamin D insufficiency may play a role in the pathogenesis of recurrent obstructive airway diseases in children. Larger prospective randomized studies are needed to confirm this hypothesis. In clinical practice, vitamin D assessment should be incorporated into the diagnostic and preventive algorithm for children with severe or recurrent ROB.