title: Periodicity of asthma, emphysema, and chronic bronchitis in a northwest health maintenance organization.
abstract: OBJECTIVE
  Since seasonal patterns in morbidity may identify triggers provoking hospital-based care for airflow obstruction, this study examined seasonal variation in patterns of hospitalizations for asthma, chronic bronchitis, and emphysema.
  
  
  METHODS
  The data for this analysis were derived from the abstracted medical records of a large health maintenance organization, Kaiser Permanente, Northwest region, over the period 1979 to 1987.
  
  
  METHODS
  In all, 2,060 primary hospital discharges for asthma and 1,121 primary hospital discharges for the combination chronic bronchitis/emphysema were observed.
  
  
  RESULTS
  The monthly patterns varied for asthma and chronic bronchitis/emphysema, and also varied by age and sex. For young children 0 to 14 years, asthma hospitalizations peaked primarily in the fall. In contrast, for young children 0 to 14 years, hospitalizations for chronic bronchitis/ emphysema peaked in the fall/winter months. Seasonal variation decreased as age increased for chronic bronchitis/emphysema, such that for the 65+ year group, there was no seasonal variation.
  
  
  CONCLUSIONS
  A better understanding of the causes of the age-specific seasonal patterns in these obstructive respiratory diseases may help to reduce the morbidity that is associated with them.
authors.affiliation: Department of Medicine, Oregon Health Sciences University, Portland, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Osborne
authors.forename: W M
authors.initials: WM
authors.lastname: Vollmer
authors.forename: A S
authors.initials: AS
authors.lastname: Buist
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000150:complications / Q000453:epidemiology*; D001991:Bronchitis / Q000150:complications / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D005260:Female; D006279:Health Maintenance Organizations; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D007251:Influenza, Human / Q000150:complications; D008297:Male; D008875:Middle Aged; D009922:Oregon / Q000453:epidemiology; D011014:Pneumonia / Q000150:complications; D011656:Pulmonary Emphysema / Q000150:complications / Q000453:epidemiology*; D012621:Seasons