title: An analysis of factors that exacerbate asthma, based on a Japanese questionnaire.
abstract: BACKGROUND
  It is known that a wide variety of factors exacerbate asthma; however, few studies have investigated the factors that exacerbate asthma from a patient's perspective. The aim of this study was to analyze the factors that exacerbate asthma, based on a questionnaire completed by asthma patients in Niigata Prefecture.
  
  
  METHODS
  Based on questionnaires given to 3085 patients who visited the medical institutes in the Niigata Prefecture monthly from September through October 2006, groups stratified by sex, age, disease type and disease severity, were analyzed for factors contributing to asthma exacerbation, as described in the guideline of the Japanese Society of Allergology.
  
  
  RESULTS
  The leading exacerbating factor chosen by patients was a change in the weather, followed by smoking, allergen exposure, fatigue, stimulants, and air pollutants. Respiratory infection, widely recognized as a critical factor of severe exacerbation, was ranked seventh. Allergen exposure and air pollutants were prominent in younger individuals, whereas respiratory infection tended to be more common in elderly subjects. Allergen exposure, air pollutants, and exercise were significantly more common in atopic-type patients, in contrast with respiratory infection in non-atopic-type patients. According to multiple regression analysis, poor asthma control during the last one year was associated with changes in the weather, whereas the non-atopic disease type was related to exacerbation by respiratory infection. Current smoking was associated with both factors.
  
  
  CONCLUSIONS
  Many factors exacerbate asthma, depending on the individual case and his/her background. These data suggest that changes in the weather may be more important factor for patients in asthma exacerbation.
authors.affiliation: Division of Respiratory Medicine, Department of Homeostatic Regulation and Development, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Koyanagi
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Koya
authors.forename: Mayumi
authors.initials: M
authors.lastname: Sasagawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Hasegawa
authors.forename: Eiichi
authors.initials: E
authors.lastname: Suzuki
authors.forename: Masaaki
authors.initials: M
authors.lastname: Arakawa
authors.forename: Fumitake
authors.initials: F
authors.lastname: Gejyo
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000485:Allergens / Q000009:adverse effects; D001249:Asthma / Q000453:epidemiology* / Q000503:physiopathology; D015986:Confounding Factors, Epidemiologic; D018450:Disease Progression; D004781:Environmental Exposure / Q000009:adverse effects; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000453:epidemiology* / Q000503:physiopathology; D007564:Japan; D008875:Middle Aged; D012907:Smoking; D011795:Surveys and Questionnaires; D014887:Weather
chemical_list: D000485:Allergens