Evaluation of serum vitamin D3 role in relation to asthma severity, control status, and eosinophilic phenotype: evidence from an Iraqi cohort within the global initiative for asthma 2025 guideline

Abstract

Abstract Background Vitamin D3 is involved in immunological actions, and recent data indicate its role in decreasing airway inflammation, which is one of the cornerstones of asthma. Objectives To evaluate serum vitamin D3 levels in Iraqi asthmatic patients compared to healthy controls, and to investigate their relationships with asthma severity, Global Initiative for Asthma (GINA) 2025-defined control status, and the eosinophilic phenotype. Methods A case-control study of 90 asthmatics and 90 healthy subjects was performed. Asthma severity was classified as moderate (n=56) or severe (n=34); control status was categorized as controlled (n=31), partially controlled (n=34), or uncontrolled (n=25), based on GINA 2025 guidelines. Serum vitamin D3 levels were measured by AFIAS-6 immunoanalyzer using fluorescence immunoassay. Statistical analyses were conducted by Mann-Whitney U test, Kruskal-Wallis’s test, Spearman correlation, and ROC curve analysis. Results Vitamin D3 levels were significantly lower in asthma patients compared to healthy controls (p<0.001), and were markedly lower in severe asthma compared to moderate asthma (p<0.0001). Additionally, a significant progressive decrease in its levels was observed with worsening disease control (p=0.0006), along with a significant positive correlation between vitamin D3 and ACT score (p<0.001). Conclusion Vitamin D3 insufficiency is substantially related to greater severity of asthma and poor asthma control among Iraqi patients; therefore, it could serve as a potential biomarker and a target for treatment.