title: Serum Vitamin D Is Significantly Inversely Associated with Disease Severity in Caucasian Adults with Obstructive Sleep Apnea Syndrome.
abstract: OBJECTIVE
  To evaluate vitamin D (25(OH)D) levels in obstructive sleep apnea syndrome (OSAS) and possible relationships to OSAS severity, sleepiness, lung function, nocturnal heart rate (HR), and body composition. We also aimed to compare the 25(OH)D status of a subset of OSAS patients compared to controls matched for important determinants of both OSAS and vitamin D deficiency (VDD).
  
  
  METHODS
  This was a cross-sectional study conducted at an urban, clinical sleep medicine outpatient center. We recruited newly diagnosed, Caucasian adults who had recently undergone nocturnal polysomnography. We compared body mass index (BMI), body composition (bioelectrical impedance analysis), neck circumference, sleepiness (Epworth Sleepiness Scale), lung function, and vitamin D status (serum 25-hydrpoxyvitamin D (25(OH)D) across OSAS severity categories and non-OSAS subjects. Next, using a case-control design, we compared measures of serum 25(OH)D from OSAS cases to non-OSAS controls who were matched for age, gender, skin pigmentation, sleepiness, season, and BMI.
  
  
  RESULTS
  106 adults (77 male; median age = 54.5; median BMI = 34.3 kg/m(2)) resident in Dublin, Ireland (latitude 53°N) were recruited and categorized as non-OSAS or mild/moderate/severe OSAS. 98% of OSAS cases had insufficient 25(OH)D (< 75 nmol/L), including 72% with VDD (< 50 nmol/L). 25(OH)D levels decreased with OSAS severity (P = 0.003). 25(OH)D was inversely correlated with BMI, percent body fat, AHI, and nocturnal HR. Subsequent multivariate regression analysis revealed that 25(OH)D was independently associated with both AHI (P = 0.016) and nocturnal HR (P = 0.0419). Our separate case-control study revealed that 25(OH)D was significantly lower in OSAS cases than matched, non-OSAS subjects (P = 0.001).
  
  
  CONCLUSIONS
  We observed widespread vitamin D deficiency and insufficiency in a Caucasian, OSAS population. There were significant, independent, inverse relationships between 25(OH)D and AHI as well as nocturnal HR, a known cardiovascular risk factor. Further, 25(OH)D was significantly lower in OSAS cases compared to matched, non-OSAS subjects. We provide evidence that 25(OH)D and OSAS are related, but the role, if any, of replenishment has not been investigated.
authors.affiliation: Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin, Ireland.|School of Medicine and Medical Sciences, University College Dublin, Belfield, Dublin, Ireland.
authors.forename: Conor P
authors.initials: CP
authors.lastname: Kerley
authors.affiliation: Biomnis Ireland, Dublin, Ireland.|NCBES, National University of Ireland, Galway, Ireland.
authors.forename: Katrina
authors.initials: K
authors.lastname: Hutchinson
authors.affiliation: Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin, Ireland.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Bolger
authors.affiliation: Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin, Ireland.
authors.forename: Aisling
authors.initials: A
authors.lastname: McGowan
authors.affiliation: Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin, Ireland.
authors.forename: John
authors.initials: J
authors.lastname: Faul
authors.affiliation: Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin, Ireland.
authors.forename: Liam
authors.initials: L
authors.lastname: Cormican
mesh_terms: D001823:Body Composition; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000150:complications / Q000503:physiopathology; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006339:Heart Rate; D006801:Humans; D007494:Ireland; D008168:Lung / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000033:anatomy & histology; D017286:Polysomnography; D012307:Risk Factors; D012621:Seasons; D012720:Severity of Illness Index; D012880:Skin Pigmentation; D020181:Sleep Apnea, Obstructive / Q000097:blood* / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D012894:Sleep Stages; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood; D044465:White People
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: apnea-hypopnea index; diet; nutrition; obesity; obstructive sleep apnea; sunshine; vitamin D