title: Seasonal variation in thoracic vessel calcifications: evidence from a chest computed tomography study.
abstract: BACKGROUND
  Cardiovascular disease incidence and mortality exhibit a winter peak and a summer trough, a fact that could have radiological manifestations.
  
  
  OBJECTIVE
  To identify possible seasonal trends in the occurrence of thoracic vessel calcifications.
  
  
  METHODS
  505 male construction workers (aged 39-80 years) were each imaged once with chest spiral computed tomography (CT) during a 2-year period. Based on visual assessment of calcified plaques (0=no, 1=slight, 2=moderate, 3=extensive calcification), sum scores of atherosclerosis in coronary arteries, in the thoracic aorta, in the pre-cervical artery bases, and overall were constructed. The scores were regressed on the annual rank number of the CT day.
  
  
  RESULTS
  By using the cubic regression model, seasonal variation in calcified plaques in coronary arteries (P=0.003), in pre-cervical artery origins (P=0.015), and in the overall sum score (P=0.004) was observed. The peak occurred in January-February and the nadir in August. Depending on the model, about 2-3% of the variation in atherosclerotic calcifications could be explained by the season of imaging.
  
  
  CONCLUSIONS
  The observed seasonal trend in calcifications parallels with mortality reports. Seasonal variations should be considered in atherosclerosis treatment studies. Confirmatory studies using modern imaging technology are needed in different countries and geographical locations, preferably with repeat imaging of the same individuals.
authors.affiliation: Health and Work Ability, Finnish Institute of Occupational Health, Helsinki, Finland. tapio.vehmas@ttl.fi
authors.forename: Tapio
authors.initials: T
authors.lastname: Vehmas
authors.forename: Asta
authors.initials: A
authors.lastname: Hiltunen
authors.forename: Päivi
authors.initials: P
authors.lastname: Leino-Arjas
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000000981:diagnostic imaging*; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging*; D003627:Data Interpretation, Statistical; D006801:Humans; D008297:Male; D008875:Middle Aged; D013902:Radiography, Thoracic; D012189:Retrospective Studies; D012621:Seasons; D014057:Tomography, X-Ray Computed