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. Author manuscript; available in PMC: 2011 Jun 1.
Published in final edited form as: Respir Med. 2010 Jan 4;104(6):858–864. doi: 10.1016/j.rmed.2009.12.006

Table 1.

Participant Characteristics

Study Year 0
(1985–6)		 2
(1987–8)		 5
(1990–1)		 10
(1995–6)		 20
(2005–6)
Number 4549 4455 4257 3674 3416
Age – years
(mean ± SD)		 24.9 ± 3.6 26.9 ± 3.6 30.0 ± 3.6 35.0 ± 3.6 45.1 ± 3.6
Males (%) 46.4 45.3 45.0 45.0 43.0
Race – white (%) 49.4 51.0 51.5 52.0 53.8
Education - ≤ high
school (%)		 37.8 33.7 31.7 28.8 23.7*
BMI
(mean ± SD)		 24.6 ± 5.0 25.2 ± 5.3 26.2 ± 5.9 27.5 ± 6.6 29.4 ± 7.0**
Smoking - current/
previous/never (%)		 29.8/29.9/40.3 29.4/30.0/40.6 28.5/29.7/41.8 24.7/31.9/43.4 18.9*/36.2/44.9
FEV1 - % predicted
(mean ± SD)		 97.7 ± 11.8 97.5 ± 12.1 99.1 ± 13.2 98.3 ± 13.0 93.7 ± 14.6**
FVC - % predicted
(mean ± SD)		 100.3 ± 11.5 100.3 ± 11.8 101.5 ± 12.4 101.5 ± 12.4 95.8 ± 13.9**
FEV1/FVC
(mean ± SD)		 0.83 ± 0.06 0.82 ± 0.07 0.82 ± 0.07 0.82 ± 0.10 0.79 ± 0.07**

Mean ± SD unless otherwise noted.

The data are from individuals who underwent pulmonary function testing and had measurements of exhalation time available for analysis.

*

p<0.05,

**

p<0.001 compared to the baseline examination