text: Dyspnea not only affects individuals with diagnosed 
  respiratory conditions but also poses a signiﬁcant 
  burden on those with undiagnosed conditions. In a 
  systematic review by Müller et al,4 the combined 
  
  Study Design and Methods 
  Recruitment of Undiagnosed Cases and Healthy 
  Control Patients 
  Between June 2017 and January 2023, adults aged $ 18 
  years were recruited through a two-step process into the 
  Undiagnosed COPD and Asthma Population (UCAP) 
  study, a multicenter case ﬁnding study. Approval for 
  
  the study was obtained from the research ethics boards 
  of 
  the 17 participating study sites across Canada. 
  Informed, written consent was provided by all study 
  participants. 
  
  Both landlines and cellphones within a 90-minute radius 
  of any of the 17 study sites were dialed randomly. A 