Chronic Obstructive Pulmonary Disease Is Associated with Low Levels of Vitamin D

Introduction: COPD patients may be at increased risk for vitamin D (25(OH)D) deficiency, but risk factors for deficiency among COPD patients have not been extensively reported. Methods: Serum 25(OH)D levels were measured by liquid chromatography double mass spectrometry in subjects aged 4076 years from Western Norway, including 433 COPD patients (GOLD stage II-IV) and 325 controls. Levels <20 ng/mL defined deficiency. Season, sex, age, body mass index (BMI), smoking, GOLD stage, exacerbation frequency, arterial oxygen tension (PaO2), respiratory symptoms, depression (CES-D score >= 16), comorbidities (Charlson score), treatment for osteoporosis, use of inhaled steroids, and total white blood count were examined for associations with 25(OH)D in both linear and logistic regression models. Results: COPD patients had an increased risk for vitamin D deficiency compared to controls after adjustment for seasonality, age, smoking and BMI. Variables associated with lower 25(OH)D levels in COPD patients were obesity (=-6.63), current smoking (=-4.02), GOLD stage III-IV (=-4.71, =-5.64), and depression (=-3.29). Summertime decreased the risk of vitamin D deficiency (OR = 0.22). Conclusion: COPD was associated with an increased risk of vitamin D deficiency, and important disease characteristics were significantly related to 25(OH)D levels.