Table 1

Demographics and characteristics of the study population and those subjects excluded from the study*

Variable
Participants included
N = 14120
Participants excluded
N = 5930


Mean (SD)
Number (%)
Mean (SD)
Number (%)

Sex




Males

6671 (47.3)

2730 (47.8)
Females

7449 (52.8)

3200 (54.0)
Age
45.7 (19.6)

52.0 (22.8)

Smoking status




Never

7390 (52.3)

2845 (48.1)
Ex

3174 (22.5)

1633 (27.6)
Current

3556 (25.2)

1434 (24.3)
Pack Years**
0 (0 to 12)

0 (0 to 14)

Race/Ethnicity




Non-Hispanic White

5881 (41.6)

2602 (43.9)
Non-Hispanic Black

3860 (27.3)

1626 (27.4)
Mexican-American

3802 (26.9)

1504 (25.4)
Other

577 (4.1)

198 (3.3)
FEV1 (L)
3.0 (0.9)

2.8 (1.0)

FVC (L)
3.8 (1.1)

3.6 (1.1)

BMI (kg/m2)
27.0 (5.8)

26.6 (6.2)

Cholesterol (mmol/l)
5.3 (1.2)

5.3 (1.2)

Triglycerides (mmol/l)
1.6 (1.3)

1.7 (1.3)

Energy intake (kcal)
2102 (1068)

2006 (1039)

C-reactive protein (mg/dL)**
0.21 (0.21 to 0.40)

0.21 (0.21 to 0.51)

Activity level




None

2800 (19.8)

1886 (31.8)
Low

5867 (41.6)

2012 (33.9)
Moderate

4579 (32.4)

1741 (29.4)
High

874 (6.2)

291 (4.9)

* Data is presented for the population where data is available. Excluded participants had missing data on a priori confounders and/or serum markers

** Data presented as Median and IQR

McKeever et al. Respiratory Research 2008 9:67   doi:10.1186/1465-9921-9-67