Vitamin D deficiency and severity of non-cystic fibrosis bronchiectasis: a systematic review

Vitamin D deficiency is common in cystic fibrosis (CF) and may be linked to disease severity. We aimed to investigate the association between vitamin D deficiency and severity in non-CF bronchiectasis. A systematic search of PubMed and Scopus (up to December 2024) identified relevant studies. After screening 170 articles, seven met the inclusion criteria. Study quality was assessed using NIH tools. Patients with non-CF bronchiectasis had significantly lower serum 25-hydroxyvitamin D (25OHD) levels compared to healthy controls. In one study, median 25OHD was 24.7 nmol/L in patients vs. 45.3 nmol/L in controls. Another reported mean levels of 14.7 ± 9.6 ng/mL vs. 19.8 ± 6.9 ng/mL, respectively. Disease severity was assessed using validated and semi-structured measures, including the bronchiectasis severity index (BSI), number of exacerbations, pulmonary function tests (PFTs), radiological scores (Bhalla, modified Reiff), and health-related quality-of-life (HRQL) tools. Most studies reported worse severity outcomes in vitamin D-deficient patients. Although vitamin D deficiency appears to be associated with more severe non-CF bronchiectasis, heterogeneity between studies limits definitive conclusions. Future studies should incorporate standardized tools such as the eFACED score to better characterize disease severity.