title: The Christmas season as a risk factor for chronic obstructive pulmonary disease exacerbations.
abstract: BACKGROUND
  Epidemics of hospitalization for chronic obstructive pulmonary disease (COPD) occur annually during the Christmas holidays, and COPD exacerbations commonly coincide with respiratory viral infections.
  
  
  OBJECTIVE
  To compare the incidence and determinants of COPD exacerbations occurring between the Christmas holiday period and the remainder of the winter season.
  
  
  METHODS
  Seventy-one subjects with COPD of mixed severity faxed daily symptom diaries to a computer monitoring system from December 1, 2006, to April 30, 2007. Possible exacerbations prompted a home visit for assessment, spirometry and specimen collection for virological testing.
  
  
  RESULTS
  Study subjects submitted a total of 95.4% of possible daily symptom diary sheets by fax. Of 114 possible COPD exacerbations detected using the faxed diaries, 110 met the Anthonisen criteria for true exacerbations. A total of 47 exacerbations (mean 6.7/week) occurred during the Christmas holiday period, while 63 exacerbations (mean 4.3/week) occurred during the remainder of winter. Of the Christmas period exacerbations and of those in the balance of winter, 21 (44%) and 20 (32%), respectively, coincided with respiratory viral infections.
  
  
  CONCLUSIONS
  The incidence of COPD exacerbations during the Christmas period was greater than during the rest of winter in 2006/2007 and peaked immediately before Christmas - in contrast to hospital presentation for COPD, which peaked during the Christmas week. No clear role of respiratory viral infections in the increased rate of exacerbations during the Christmas period was established in the present study. COPD patients were highly compliant with daily symptom reporting using faxed daily diaries, which permitted nearly complete detection of all exacerbations that occurred at incidence.
authors.affiliation: Firestone Institute for Respiratory Health, McMaster University, Hamilton, Ontario. njohnsto@mcmaster.ca
authors.forename: Neil W
authors.initials: NW
authors.lastname: Johnston
authors.forename: Andrew
authors.initials: A
authors.lastname: McIvor
authors.forename: Kim
authors.initials: K
authors.lastname: Lambert
authors.forename: Justina M
authors.initials: JM
authors.lastname: Greene
authors.forename: Pat
authors.initials: P
authors.lastname: Hussack
authors.forename: Maria
authors.initials: M
authors.lastname: Gerhardsson de Verdier
authors.forename: Tim
authors.initials: T
authors.lastname: Higenbottam
authors.forename: Jonathan
authors.initials: J
authors.lastname: Lewis
authors.forename: Paul
authors.initials: P
authors.lastname: Newbold
authors.forename: Athula
authors.initials: A
authors.lastname: Herath
authors.forename: Martin
authors.initials: M
authors.lastname: Jenkins
mesh_terms: D000328:Adult; D000368:Aged; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology*; D012141:Respiratory Tract Infections / Q000453:epidemiology*; D012307:Risk Factors; D012621:Seasons