title: Can serial PEF measurements separate occupational asthma from allergic alveolitis?
abstract: BACKGROUND
  Occupational asthma commonly results in work-related changes in serial peak expiratory flow (PEF) measurements. Whether alveolitis can result in similar changes is unknown.
  
  
  OBJECTIVE
  To identify differences and similarities of serial PEF between workers with occupational alveolitis and asthma seen during an outbreak investigation in a factory with metal-working fluid exposure.
  
  
  METHODS
  Workers with respiratory symptoms and rest-day improvement were identified by questionnaire. Each was asked to measure PEF 8 times daily for 4 weeks at home and work. Alveolitis was subsequently diagnosed from a validated scoring system including radiological changes, carbon monoxide diffusing capacity, bronchoalveolar lavage and biopsy results. Occupational asthma was confirmed with a positive Oasys score >2.5 and a mean rest-work PEF >16 l/min from serial 2-hourly PEF measurements. The Oasys PEF plotter calculated differences between rest and workdays for mean PEF, diurnal variation and the scores were used to confirm an occupational effect (Oasys, area between curve and time point). Records were compared between the alveolitis group and the group with occupational asthma without alveolitis.
  
  
  RESULTS
  Forty workers with occupational asthma and 16 with alveolitis had indistinguishable PEF changes on workdays in terms of magnitude (median reduction 18.5 and 16.1 l/min, respectively) and diurnal variation. Immediate reactions were more common with occupational asthma and late reactions more common with alveolitis.
  
  
  CONCLUSIONS
  PEF responses to metal-working fluid aerosols do not distinguish occupational asthma from alveolitis except in timing. They can be used to identify the workplace as the cause of asthma and also alveolitis.
authors.affiliation: Occupational Lung Disease Unit, Birmingham Heartlands Hospital, Birmingham B9 5SS, UK, sherwood.burge@heartofengland.nhs.uk.
authors.forename: P S
authors.initials: PS
authors.lastname: Burge
authors.affiliation: Occupational Lung Disease Unit, Birmingham Heartlands Hospital, Birmingham B9 5SS, UK.
authors.forename: V C
authors.initials: VC
authors.lastname: Moore
authors.affiliation: Occupational Lung Disease Unit, Birmingham Heartlands Hospital, Birmingham B9 5SS, UK.
authors.forename: C B S G
authors.initials: CB
authors.lastname: Burge
authors.affiliation: Occupational Lung Disease Unit, Birmingham Heartlands Hospital, Birmingham B9 5SS, UK.
authors.forename: A D
authors.initials: AD
authors.lastname: Vellore
authors.affiliation: Occupational Lung Disease Unit, Birmingham Heartlands Hospital, Birmingham B9 5SS, UK.
authors.forename: A S
authors.initials: AS
authors.lastname: Robertson
authors.affiliation: Department of Public Health, Warwick Medical School, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: W
authors.initials: W
authors.lastname: Robertson
mesh_terms: D000328:Adult; D000542:Alveolitis, Extrinsic Allergic / Q000150:complications / Q000175:diagnosis*; D001249:Asthma / Q000175:diagnosis* / Q000209:etiology; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D016273:Occupational Exposure / Q000009:adverse effects / Q000706:statistics & numerical data; D010366:Peak Expiratory Flow Rate / Q000502:physiology*; D012680:Sensitivity and Specificity
keywords: Allergic alveolitis; Oasys; hypersensitivity pneumonitis; meta-working fluid; occupational asthma; peak expiratory flow.