title: Determination of the efficacy of FEV6 as a surrogate for FVC in the diagnostic screening for chronic obstructive pulmonary disease through the comparison of FEV1/FVC and FEV1/FEV6 ratios.
abstract: OBJECTIVE
  To determine the efficacy of using forced expiratory volume in six seconds (FEV6) as a surrogate for forced vital capacity (FVC) in the diagnostic screening for chronic obstructive pulmonary disease (COPD) by comparing FEV1/FVC ratios with FEV1/FEV6 ratios.
  
  
  METHODS
  In November of 2003, on World COPD Day, we conducted a campaign of diagnostic screening for COPD. The participants completed the clinical questionnaire of the Global Initiative for Obstructive Lung Disease, and those who responded affirmatively to at least three questions underwent spirometry.
  
  
  RESULTS
  A total of 134 individuals responded to three questions affirmatively and underwent spirometry. Of those, 59 were excluded: 45 for being non-smokers and 14 due to the fact that their tests did not meet the American Thoracic Society criteria for satisfactory spirometry. The number of tests in which the FEV1/FEV6 ratio was below 70% was similar to that found for the FEV1/FVC ratio. The sensitivity of FEV1/FEV6 in diagnosing airway obstruction (defined as FEV1/FVC below 70%) was 92%, and its specificity was 99%. The positive predictive value was 100%, and the negative predictive value was 98%. The Kendall correlation test revealed r = 0.99 (p < 0.0001). The t-test for paired samples revealed a negative correlation: t = -5.93 (p < 0.0001).
  
  
  CONCLUSIONS
  The FEV1/FEV6 proved efficient for use in the diagnostic screening for COPD. There is a strong correlation between FEV1/FVC and FEV1/FEV6.
authors.affiliation: Otávio de Freitas General Hospital, Recife, PE, Brasil. lundgrenf@gmail.com <lundgrenf@gmail.com>
authors.forename: Fernando Luiz Cavalcanti
authors.initials: FL
authors.lastname: Lundgren
authors.forename: Marília Montenegro
authors.initials: MM
authors.lastname: Cabral
authors.forename: Danielle Cristina Silva
authors.initials: DC
authors.lastname: Clímaco
authors.forename: Liana Gonçalves
authors.initials: LG
authors.lastname: de Macedo
authors.forename: Marta de Andrade Lima
authors.initials: Mde A
authors.lastname: Coelho
authors.forename: Ana Lúcia Pereira Lima Alves
authors.initials: AL
authors.lastname: Dias
mesh_terms: D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology*; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000503:physiopathology; D012129:Respiratory Function Tests / Q000592:standards; D012907:Smoking; D013147:Spirometry / Q000706:statistics & numerical data; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires; D014797:Vital Capacity / Q000502:physiology*