title: Diagnostic accuracy of pre-bronchodilator FEV1/FEV6 from microspirometry to detect airflow obstruction in primary care: a randomised cross-sectional study.
abstract: BACKGROUND
  Forced expiratory volume in 1s/forced expiratory volume in 6 s ( FEV1/FEV6) assessment with a microspirometer may be useful in the diagnostic work up of subjects who are suspected of having COPD in primary care.
  
  
  OBJECTIVE
  To determine the diagnostic accuracy of a negative pre-bronchodilator (BD) microspirometry test relative to a full diagnostic spirometry test in subjects in whom general practitioners (GPs) suspect airflow obstruction.
  
  
  METHODS
  Cross-sectional study in which the order of microspirometry and diagnostic spirometry tests was randomised. Study subjects were (ex-)smokers aged ≥50 years referred for diagnostic spirometry to a primary care diagnostic centre by their GPs. A pre-BD FEV1/FEV6 value <0.73 as measured with the PiKo-6 microspirometer was compared with a post-BD FEV1/FVC (forced vital capacity) <0.70 and FEV1/FVC<lower limit of normal (LLN) from diagnostic spirometry.
  
  
  RESULTS
  One hundred and four subjects were analysed (59.6% males, 42.3% current smokers). Negative predictive values from microspirometry for airflow obstruction based on the fixed and LLN cut-off points were 94.4% (95% confidence interval (CI), 86.4-98.5) and 96.3% (95% CI, 88.2-99.3), respectively. In all, 18% of positive microspirometry results were not confirmed by a post-BD FEV1/FVC <0.70 and 44% of tests were false positive compared with the LLN criterion for airflow obstruction.
  
  
  CONCLUSIONS
  Pre-bronchodilator microspirometry seems to be able to reliably preselect patients for further assessment of airflow obstruction by means of regular diagnostic spirometry. However, use of microspirometry alone would result in overestimation of airflow obstruction and should not replace regular spirometry when diagnosing COPD in primary care.
authors.affiliation: Department of Primary and Community Care, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Lisette
authors.initials: L
authors.lastname: van den Bemt
authors.affiliation: Department of Primary and Community Care, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Bram C W
authors.initials: BC
authors.lastname: Wouters
authors.affiliation: Department of Primary and Community Care, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Joke
authors.initials: J
authors.lastname: Grootens
authors.affiliation: Centre for Diagnostic Support in Primary Care, Stichting Huisartsen Laboratorium, Etten-Leur, The Netherlands.
authors.forename: Joke
authors.initials: J
authors.lastname: Denis
authors.affiliation: Department of Primary and Community Care, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Poels
authors.affiliation: Department of Primary and Community Care, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Tjard R
authors.initials: TR
authors.lastname: Schermer
mesh_terms: D000368:Aged; D001993:Bronchodilator Agents; D003430:Cross-Sectional Studies; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D011320:Primary Health Care; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000503:physiopathology; D015203:Reproducibility of Results; D013147:Spirometry / Q000379:methods*
chemical_list: D001993:Bronchodilator Agents