title: Smoking, respiratory symptoms and likely asthma in young people: evidence from postal questionnaire surveys in the Wythenshawe Community Asthma Project (WYCAP).
abstract: BACKGROUND
  Although it is recognised that smoking is a major risk factor for subjects with chronic obstructive pulmonary disease and is associated with respiratory symptoms, there is less agreement concerning the relationship between asthma and smoking. This study aims to examine the relationship between cigarette smoking and asthma prevalence.
  
  
  METHODS
  Data were used from two postal questionnaire surveys (1999 and 2001) in two general practice populations, using a respiratory questionnaire based on the ECRHQ and a generic quality of life questionnaire (EQ-5D). Only subjects less than 45 years old were included in the survey. An empirical definition of likely asthma was used based on respiratory questionnaire responses. Smoking was examined according to three categories, current smoker, ex smoker and never smoker.
  
  
  RESULTS
  Almost 3500 subjects were included in the analyses. Current smokers had a higher prevalence of likely asthma compared to never smokers, odds ratio (OR) 1.59 (95% confidence interval (CI) 1.24 to 2.04). and also compared to ex smokers OR 1.79 (CI 1.25 to 2.56), but there was no difference between ex smokers and never smokers (OR 1.00 (0.75-1.35)). Current smoking was also positively associated with all symptoms but not with a history of hayfever/eczema.
  
  
  CONCLUSIONS
  Although the positive association found between current smoking and obstructive airways disease is likely to be due to the effect of cigarettes on asthma, it could reflect an association with early COPD (GOLD stages 0 or 1). Smoking cessation has a beneficial effect on the prevalence of respiratory symptoms and is therefore of paramount importance among these young adults.
authors.affiliation: General Practice Research Unit, North West Lung Research Centre, Wythenshawe Hospital, Southmoor Road, Manchester, M23 9LT, UK. gpresearchunit@yahoo.co.uk
authors.forename: Peter
authors.initials: P
authors.lastname: Frank
authors.forename: Julie
authors.initials: J
authors.lastname: Morris
authors.forename: Michelle
authors.initials: M
authors.lastname: Hazell
authors.forename: Mary
authors.initials: M
authors.lastname: Linehan
authors.forename: Timothy
authors.initials: T
authors.lastname: Frank
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D012120:Respiration Disorders / Q000453:epidemiology / Q000209:etiology*; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D011795:Surveys and Questionnaires; D006113:United Kingdom