text: Our study has limitations. We did not undertake 
  reliability/reproducibility testing of our questionnaire. 
  The dyspnea impact assessment score was statistically 
  associated with increased health care utilization, lower 
  quality of life, and reduced work productivity; therefore, 
  by virtue of this analysis, our questionnaire has 
  construct validity. However, further attempts at external 
  validation of the questionnaire using an independent 
  data set would be important. Health care utilization 
  during the preceding 12 months was assessed on entry 
  into the study, and there is potential for impaired recall 
  of events. Our study may have missed asthma in some 
  participants because bronchial challenge testing was not 
  conducted on those who tested negative for airﬂow 
  obstruction or BD responsiveness. A previous study 
  showed that an additional diagnostic step incorporating  Our study complements the literature by focusing on 
  adults with undiagnosed respiratory symptoms who 
  were randomly selected and recruited through active 
  case ﬁnding in the community. This increases the 
  generalizability of our results to a broader population. 
  Our dyspnea questions were derived from widely used 
  
  TABLE 9 ] Unadjusted and Adjusted Dyspnea Associations With Work Productivity (WPAI) 