title: Factors affecting peak expiratory flow variability and bronchial reactivity in a random population sample.
abstract: BACKGROUND
  Bronchial reactivity measurements are widely used in epidemiological studies to provide an objective marker of asthma. There are, however, several potential advantages of measuring peak expiratory flow (PEF) variability instead, particularly in large studies. PEF variability and bronchial reactivity were compared in a population sample to assess the relationships of the two measurements to factors known to be associated with airways disease, and to compare their response rates.
  
  
  METHODS
  Subjects aged 18-65 were randomly selected from the electoral register of an administrative area in eastern England and randomised to attend either for a bronchial challenge test measuring the provocative dose of methacholine producing a 20% fall in FEV1 (PD20), or to measure PEF at two hourly intervals during waking hours for one week. Skin tests with common allergens were performed and a smoking history obtained. PEF variability was expressed as the amplitude % mean (highest - lowest x 100/mean).
  
  
  RESULTS
  A total of 273 subjects (69%) collected a PEF meter but a completed record sheet was returned by only 247 (62%); this was still significantly more than the 202 subjects (54%) who attended for and successfully completed a challenge test. Amplitude % mean was higher in women than in men (9.7% v 8.5%). In multiple regression analysis amplitude % mean increased significantly with age, mean skin weal diameter, and with current smoking. The odds of having a PD20 below 24.5 mumol increased with mean skin weal diameter and were greater in current smokers. Neither age nor sex had a significant effect on bronchial reactivity but there were significant interactions between age and the effects of both smoking and atopy.
  
  
  CONCLUSIONS
  The higher response rate associated with the use of PEF variability measurement, and the association with factors implicated in the pathogenesis of airways disease, suggest that PEF variability would be a useful measurement to employ in epidemiological studies.
authors.affiliation: Respiratory Medicine Unit, City Hospital, Nottingham, UK.
authors.forename: B G
authors.initials: BG
authors.lastname: Higgins
authors.forename: J R
authors.initials: JR
authors.lastname: Britton
authors.forename: S
authors.initials: S
authors.lastname: Chinn
authors.forename: K K
authors.initials: KK
authors.lastname: Lai
authors.forename: P G
authors.initials: PG
authors.lastname: Burney
authors.forename: A E
authors.initials: AE
authors.lastname: Tattersfield
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging / Q000502:physiology; D001980:Bronchi / Q000502:physiology; D001985:Bronchial Provocation Tests; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000503:physiopathology; D008168:Lung / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate; D011897:Random Allocation; D012727:Sex Characteristics; D012907:Smoking; D014797:Vital Capacity