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

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.