呼吸器・呼吸器内科

Vitamin D and Diagnosis of COPD in a Working Population

Abstract

Koichi Nishimura, Miyoko Ogasawara, Mariko Makita, Kazuhito Nakayasu, Yoshinori Hasegawa and Satoshi Mitsuma

Background: Some epidemiologic studies have proven the possible association between the serum level of 25-hydroxy vitamin D [25(OH)D] and the forced expiratory volume in 1 second (FEV1 ) or chronic obstructive pulmonary disease (COPD). Purpose: To investigate whether serum concentrations of 25(OH)D play a role in the diagnosis of COPD in a working population.

Patients and methods: A total of 299 industrial workers aged ≥ 40 years performed spirometry and had their serum level of 25(OH)D measured.

Results: The prevalence of COPD defined by the fixed ratio was 14.1%. Mean 25(OH)D levels did not differ significantly between subjects with COPD and those without COPD as defined by the fixed ratio (24.6 ng/mL ± 6.7 ng/ mL in subjects with COPD vs. 24.0 ng/mL ± 5.9 ng/mL in subjects without COPD; not significantly different). According to an Endocrine Society Clinical Practice Guideline released in the US in 2011, vitamin D insufficiency, defined as 25(OH)D levels of <30 ng/mL, was present in 252 (84.2%) out of the 299 participants, and vitamin D deficiency, defined as 25(OH)D levels of <20 ng/mL, was found in 80 (26.8%) subjects. Forced expiratory volume in 1 second (FEV1 ), forced vital capacity (FVC), FEV1 /FVC and the prevalence of subjects with COPD were not significantly different among the three groups with different 25(OH)D levels (≧ 30 ng/mL, ≧ 20 and <30 ng/mL and <20 ng/mL). Statistically significant correlations were not found between any measurements obtained from spirometry, including FEV1, FEV1 / FVC, and 25(OH)D levels.

Conclusion: Although vitamin D insufficiency and deficiency were frequently observed in the present study, the serum 25(OH)D concentration was not different between COPD and non-COPD subjects in a working population. The association between 25(OH)D levels and COPD did not meet a level of statistical significance in the present study conducted in a working population.