text: Risk Factors Associated With Dyspnea 
  Patient-related risk factors were considered ﬁrst, and re- 
  sults of spirometry considered afterward. The spirom- 
  etry risk factors chosen for the second stage analysis 
  included the spirometry-based diagnosis of the patient 
  (asthma, COPD, PRISm, or normal) and lung function 
  results indicative of the severity of physiologic impair- 
  ment. Severity was gauged by assessing three principal 
  lung function measures: (1) post-BD FEV1 % predicted, 
  (2) post-BD FEV1/FVC ratio, and (3) percentage 
  reversal of FEV1 with BD. 
  
  indicate greater impairment in work productivity and 
  daily activities. 
  
  Statistical Analysis 
  
  Box plots were used to compare distribution patterns of 
  dyspnea impact assessments among the disease groups. 
  Pairwise comparison tests were conducted to evaluate 
  mean dyspnea differences between groups. Multiple 
  linear regression analysis was used to measure contribu- 
  tions to variability of dyspnea by selected patient-speciﬁc 
  risk factors, spirometry disease classiﬁcation, and key 
  lung function measures. The selected sets of risk factors 
  were evaluated using successive regression analyses. 
  Analysis of variance sums of squares from the successive 
  regression analyses provided the cumulative percentage 
  contributions to variability of dyspnea. Simple, multiple, 
  and logistic regression analyses were used to study asso- 
  ciations between dyspnea and health care utilization, 
  quality of life, and work productivity outcomes. All sta- 
  tistical analyses were done using STATA 16 statistical 
  software (StataCorp). 