Indoor Employment as a Factor Associated with Serum Vitamin D Levels in Obstructive Sleep Apnoea Syndrome

Background/Objectives: Variations in Vitamin D (Vit D) levels have been described among individuals working in different settings. Moreover, published evidence sug-gests an association between obstructive sleep apnea-syndrome (OSAS) and Vit D in-sufficiency. The aim of this study was to assess the association between certain expo-sures at the occupational environment and Vit D levels, in relation to OSAS severity. Methods: For a period of 12 months, Vit D serum levels were assessed in subjects con-secutively investigated for OSAS. These were divided into group A (control subjects working indoors), group B (control subjects working outdoors), group C (OSAS pa-tients working indoors) and group D (OSAS patients working outdoors). Results: A total of 189 subjects were included (155 males and 34 females), comprising 129 OSAS patients and 60 non-apneic controls. Serum 25(OH)D levels were significantly higher in group B compared to the other groups (32.2 ± 13 vs 22.9 ± 6.7 ng/ml for group A, p = 0.001 vs 15.2 ± 7.6 ng/ml for group C, p < 0.001 vs 22.9 ± 9.3 ng/ml for group D, p < 0.001). Additionally, serum 25(OH)D levels were increased in group A compared with group C (22.9 ± 6.7 vs 15.2 ± 7.6 ng/ml respectively, p = 0.001) and were similar be-tween groups A and D (22.9 ± 6.7 vs 22.9 ± 9.3 respectively, p > 0.05). Regression analy-sis revealed that AHI (β = 0.023, OR: 1.023, 95% CI: 1.003 – 1.043, p = 0.022) and indoor occupation (β = 1.030, OR: 2.802, 95% CI: 1.172 – 6.699, p = 0.021) were associated with Vit D insufficiency. Conclusions: Serum Vit D levels are decreased in OSAS patients working indoors. Thus, the working environment should also be considered in the overall assessment of Vit D status in OSAS patients.