Vitamin D deficiency in patients evaluated for obstructive sleep apnea: is it associated with disease severity?

Purpose: The aim of the present study was to assess vitamin D levels in a large cohort of OSA patients and to investigate possible correlations with clinical and polysomnographic parameters. Methods: In this cross-sectional study, 685 consecutive patients underwent type 1 polysomnography (PSG) for OSA diagnosis. They were grouped according to apnea–hypopnea index (AHI) as mild, moderate, and severe. Patients with AHI < 5 served as controls. Demographic, PSG data, and serum levels of vitamin D were measured and compared between groups. Results: OSA was diagnosed in 617 of the patients (90%). Of those, 94 (15%) had mild OSA, 150 (24%) moderate OSA, and 373 (61%) severe OSA. The risk of vit…