title: Serum 25-hydroxyvitamin D3 and the risk of pneumonia in an ageing general population.
abstract: BACKGROUND
  Vitamin D has been suggested to have a role in infection defence and on the immune system. We therefore investigated the effect of serum 25-hydroxyvitamin D₃ (25(OH)D₃) on the risk of incident hospitalised pneumonia in an ageing general population in eastern Finland.
  
  
  METHODS
  The study population included 723 men and 698 women aged 53-73 years from the prospective population-based Kuopio Ischemic Heart Disease Risk Factor study who were free of pneumonia, other pulmonary diseases and cancer at baseline in 1998-2001. Incident pneumonia episodes leading to hospitalisation were collected by record linkage to the hospital discharge register. The serum vitamin D status was assayed as 25(OH)D₃ concentration. Cox proportional hazards regression models were used to analyse the effect of serum 25(OH)D₃ on the risk of incident pneumonia.
  
  
  RESULTS
  The mean (SD) serum 25(OH)D₃ concentration of the study population was 43.5 (17.8) nmol/l. 73 subjects had at least one hospitalisation episode due to pneumonia during an average follow-up of 9.8 years. After multivariable adjustments, the subjects in the lowest serum 25(OH)D₃ tertile had a 2.6-fold (95% CI 1.4 to 5.0, p trend across tertiles=0.005) higher risk of developing pneumonia compared with the subjects in the highest tertile. This significant result remained even after adjustment for the determinants of serum 25-hydroxyvitamin D₃.
  
  
  CONCLUSIONS
  These data suggest an inverse effect of serum 25(OH)D₃ concentration on the risk of incident pneumonia in the general ageing population.
authors.affiliation: Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Yliopistonranta 1C, P O Box 1627, Kuopio, North Savo FI70211, Finland. alex.aregbesola@uef.fi
authors.forename: Alex
authors.initials: A
authors.lastname: Aregbesola
authors.forename: Sari
authors.initials: S
authors.lastname: Voutilainen
authors.forename: Tarja
authors.initials: T
authors.lastname: Nurmi
authors.forename: Jyrki K
authors.initials: JK
authors.lastname: Virtanen
authors.forename: Kimmo
authors.initials: K
authors.lastname: Ronkainen
authors.forename: Tomi-Pekka
authors.initials: TP
authors.lastname: Tuomainen
mesh_terms: D000368:Aged; D002112:Calcifediol / Q000097:blood*; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000097:blood* / Q000453:epidemiology*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D002112:Calcifediol
keywords: 25-hydroxyvitamin D3; ageing; infection; pneumonia; prospective study; vitamin D