text: Classiﬁcation of Undiagnosed Cases 
  Certiﬁed study personnel administered spirometry tests 
  before and after BD use. Participants showing an in- 
  crease of at least 12% and 200 mL in their FEV1 after 
  receiving 400 mg of salbutamol were classiﬁed as having 
  spirometry indicative of asthma.17 Those whose post-BD 
  ratio of FEV1/FVC fell below the lower 95% conﬁdence 
  limit (ie, FEV1/FVC < lower limit of normal) were clas- 
  siﬁed as having spirometry indicative of COPD.18 Partic- 
  ipants meeting the criteria for both conditions were 
  labeled as having COPD. Those with a post-BD 
  < 80% of the predicted normal and a post-BD 
  FEV1 
  FEV1/FVC ratio > 0.70 were classiﬁed as having 
  spirometry indicative of preserved ratio impaired 
  spirometry (PRISm). PRISm was deﬁned based on 
  post-BD spirometry values for a more speciﬁc classiﬁca- 
  tion.19 Participants not meeting criteria for asthma, 
  COPD, or PRISm were labeled as having normal 
  spirometry. 