Table 2 Distribution of demographic characteristics for NETT COPD cases and NAS controls
Demographic characteristicsNETT(n = 389)NAS(n = 420)p Value
Age (years)67 (6)68 (9)0.9
Pack-years66 (30)39 (27)<0.001
FEV1 (% predicted, post-BD)*28 (7)92 (11)
Median (IQR) modified BODE score†5 (3)NA
Gender (% male)64%100%

  • Values are mean (SD) unless otherwise stated.

  • BD, bronchodilator; FEV1, forced expiratory volume in 1 s; IQR, interquartile range; NAS, Normative Aging Study; NETT, National Emphysema Treatment Trial.

  • *FEV1 percentage predicted values for the NETT and NAS are based on the prediction equations of Crapo et al;36 however, the NAS-1988 standards were used in the selection of the control group.

  • †Modified BODE score incorporates the University of San Diego Shortness of Breath Questionnaire.