Proportion of Vitamin D Deficiency among Chronic Obstructive Pulmonary Disease Patients and Its Correlation with Lung Function – A Cross-sectional Study

Background: Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. Vitamin D deficiency has been implicated in immune dysregulation and may influence disease severity and exacerbation risk in COPD. This study aimed to estimate the prevalence of Vitamin D deficiency among COPD patients and assess its correlation with lung function. Methods: This cross-sectional study was conducted among 82 COPD patients aged >40 years diagnosed by spirometry (forced expiratory volume in 1 s [FEV1]/Forced Vital Capacity [FVC] <0.70) attending a tertiary care centre. Demographic, clinical, and spirometric data were collected. Serum 25-hydroxyvitamin D levels were measured using a fully automated analyzer. Vitamin D status was categorized as deficiency (<20 ng/mL), insufficiency (20–29 ng/mL), and sufficiency (≥30 ng/mL). Categorical variables were expressed as percentages and analyzed using the Chi-square test, while continuous variables were expressed as mean ± standard deviation. Correlation between Vitamin D levels and lung function parameters was assessed using appropriate statistical tests. P < 0.05 was considered statistically significant. Results: The prevalence of Vitamin D deficiency among COPD patients was 34.1%. Lower Vitamin D levels were associated with increased frequency of exacerbations. A weak positive correlation was observed between Vitamin D levels and post-bronchodilator FEV1 and FVC. Vitamin D deficiency was more common among patients in GOLD Group E and those with severe airflow limitation (GOLD grades 3 and 4). Conclusion: Vitamin D deficiency is common in patients with COPD and is associated with increased disease severity and exacerbation frequency. These findings highlight the potential role of Vitamin D in the clinical course of COPD and the need for further studies to evaluate the benefits of supplementation.