title: Dissociation of dysfunctional breathing and odour intolerance among adults in a general-population study.
abstract: BACKGROUND
  Many patients present with a mixture of respiratory problems such as shortness of breath, heavy breathing, coughing and odour intolerance. If these patients are diagnosed as asthma, it might sometimes be a false diagnosis. Concepts such as sensory hyperreactivity, hyperventilation, asthma-like symptoms, odour intolerance and dysfunctional breathing are used to refer to these patients. Non-respiratory symptoms such as headache, fatigue and bloating are sometimes also part of the clinical picture. Our aim was to use factor analysis to increase our understanding of breathing-related symptoms in a general-population frame.
  
  
  METHODS
  A respiratory questionnaire was answered by 10 108 subjects in a general-population sample. Items aiming to identify individuals with breathing-related symptoms and asthma were included. We used factor analysis with Varimax rotation to extract discriminatory components (i.e. groups of symptoms), based on the questionnaire items. The aim was to find groups of items (factors) as distinct as possible, still allowing overlap and showing the importance of each item in the separated factor.
  
  
  RESULTS
  Five distinct factors were identified in the factor analysis, representing dysfunctional breathing, odour intolerance, asthma, bronchitis and a group with mixed symptoms, respectively. These five factors explained 55% of the variance.
  
  
  CONCLUSIONS
  Based on our findings, we conclude that non-asthmatic breathing-related symptoms may be separated into at least two categories in a general population, odour intolerance and dysfunctional breathing. These two categories seem to be two distinct groups of subjects with breathing-related symptoms and may represent different clinical entities separated from asthma and bronchitis.
authors.affiliation: Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden. ellen.bonde@amm.gu.se
authors.forename: Ellen
authors.initials: E
authors.lastname: Bonde
authors.forename: Eva
authors.initials: E
authors.lastname: Andersson
authors.forename: Jonas
authors.initials: J
authors.lastname: Brisman
authors.forename: Mats
authors.initials: M
authors.lastname: Eklöf
authors.forename: Karin C
authors.initials: KC
authors.lastname: Ringsberg
authors.forename: Kjell
authors.initials: K
authors.lastname: Torén
mesh_terms: D000328:Adult; D001249:Asthma / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D016535:Bronchial Hyperreactivity / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006985:Hyperventilation / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018777:Multiple Chemical Sensitivity / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D009812:Odorants; D011788:Quality of Life; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology