title: Association between prehospital vitamin D status and incident acute respiratory failure in critically ill patients: a retrospective cohort study.
abstract: OBJECTIVE
  We hypothesise that low 25-hydroxyvitamin D (25(OH)D) levels before hospitalisation are associated with increased risk of acute respiratory failure.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Medical and Surgical Intensive care units of two Boston teaching hospitals.
  
  
  METHODS
  1985 critically ill adults admitted between 1998 and 2011.
  
  
  METHODS
  None.
  
  
  RESULTS
  The exposure of interest was prehospital serum 25(OH)D categorised as ≤10 ng/mL, 11-19.9 ng/mL, 20-29.9 ng/mL and ≥30 ng/mL. The primary outcome was acute respiratory failure excluding congestive heart failure determined by International Classification of Diseases Ninth Edition (ICD-9) coding and validated against the Berlin Definition of acute respiratory sistress syndrome. Association between 25(OH)D and acute respiratory failure was assessed using logistic regression, while adjusting for age, race, sex, Deyo-Charlson Index and patient type (medical vs surgical). In the cohort, the mean age was 63 years, 45% were male and 80% were white; 25(OH)D was ≤10 ng/mL in 8% of patients, 11-19.9 ng/mL in 24%, 20-29.9 ng/mL in 24% and ≥30 ng/mL in 44% of patients. Eighteen per cent (n=351) were diagnosed with acute respiratory failure. Compared to patients with 25(OH)D ≥30 ng/mL, patients with lower 25(OH)D levels had significantly higher adjusted odds of acute respiratory failure (≤10 ng/mL, OR=1.84 (95% CI 1.22 to 2.77); 11-19.9 ng/mL, OR=1.60 (95% CI 1.19 to 2.15); 20-29.9 ng/mL, OR=1.37 (95% CI 1.01 to 1.86)).
  
  
  CONCLUSIONS
  Prehospital 25(OH)D was associated with the risk of acute respiratory failure in our critically ill patient cohort.
authors.affiliation: School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham , Birmingham , UK.
authors.forename: David R
authors.initials: DR
authors.lastname: Thickett
authors.affiliation: Department of Medicine , Hokubu Prefectural Hospital , Nago City , Japan.
authors.forename: Takuhiro
authors.initials: T
authors.lastname: Moromizato
authors.affiliation: Channing Division of Network Medicine and Pulmonary and Critical Care Division, Department of Medicine , Brigham and Women's Hospital , Boston, Massachusetts , USA.
authors.forename: Augusto A
authors.initials: AA
authors.lastname: Litonjua
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine , Medical University of Graz , Graz , Austria.
authors.forename: Karin
authors.initials: K
authors.lastname: Amrein
authors.affiliation: Department of Anesthesia, Critical Care and Pain Medicine , Massachusetts General Hospital , Boston, Massachusetts , USA.
authors.forename: Sadeq A
authors.initials: SA
authors.lastname: Quraishi
authors.affiliation: Department of Medicine , Brigham and Women's Hospital , Boston, Massachusetts , USA.
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Lee-Sarwar
authors.affiliation: Department of Nutrition , Brigham and Women's Hospital , Boston, Massachusetts , USA.
authors.forename: Kris M
authors.initials: KM
authors.lastname: Mogensen
authors.affiliation: Division of Pulmonary Sciences and Critical Care Medicine , University of Colorado , Denver, Colorado , USA.
authors.forename: Steven W
authors.initials: SW
authors.lastname: Purtle
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine , Massachusetts General Hospital , Boston, Massachusetts , USA.
authors.forename: Fiona K
authors.initials: FK
authors.lastname: Gibbons
authors.affiliation: Department of Emergency Medicine , Massachusetts General Hospital , Boston, Massachusetts , USA.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Camargo
authors.affiliation: Departments of Nutrition and Epidemiology , Harvard School of Public Health , Boston, Massachusetts , USA.
authors.forename: Edward
authors.initials: E
authors.lastname: Giovannucci
authors.affiliation: The Nathan E. Hellman Memorial Laboratory, Renal Division , Brigham and Women's Hospital , Boston, Massachusetts , USA.
authors.forename: Kenneth B
authors.initials: KB
authors.lastname: Christopher
keywords: ARDS; Clinical Epidemiology