Table 2.
Demographic characteristics of participants in the two study populations of the NLST determined by the center's distribution of sex.a
| Total NLST 33 Centers | Trial sample: 23 Centers with females ≥40% | Target population: 10 Centers with females <40% | ||
|---|---|---|---|---|
| Characteristics | (N = 53,452) | (N = 29,848) | (N = 23,604) | P valueb |
| Age at randomization | 61.4 ± 5.0 | 61.4 ± 5.0 | 61.5 ± 5.0 | 0.01 |
| Sex | <0.001 | |||
| Male | 59.0 | 55.8 | 63.0 | |
| Female | 41.0 | 44.2 | 37.0 | |
| Ethnic group | 0.47 | |||
| Hispanic | 1.8 | 1.7 | 1.8 | |
| Non-Hispanic | 97.5 | 97.7 | 97.3 | |
| Others or missing | 0.7 | 0.6 | 0.9 | |
| Education status | 0.79 | |||
| Less than college | 43.8 | 43.8 | 43.7 | |
| College or higher | 53.9 | 53.7 | 54.2 | |
| Others or missing | 2.3 | 2.5 | 2.1 | |
| Marital status | <0.001 | |||
| Single | 4.7 | 4.9 | 4.2 | |
| Married | 66.6 | 65.3 | 68.2 | |
| Widowed/divorced | 28.1 | 29.0 | 27.1 | |
| Missing | 0.6 | 0.7 | 0.5 | |
| Smoking status | 0.001 | |||
| Current | 48.2 | 48.9 | 47.4 | |
| Former | 51.8 | 51.1 | 52.6 | |
| BMI (kg/m2) | 0.74 | |||
| <25 | 28.6 | 28.8 | 28.5 | |
| 25 to <30 | 42.6 | 42.5 | 42.8 | |
| ≥30 | 28.1 | 28.1 | 28.1 | |
| Missing | 0.7 | 0.7 | 0.7 | |
| Study | <0.001 | |||
| LSS | 64.8 | 46.1 | 88.4 | |
| ACRIN | 35.2 | 53.9 | 11.6 |
Abbreviations: ACRIN, American College of Radiology Imaging Network; BMI, body mass index; LSS, Lung Screening Study.
aData are presented as a percentage or mean ± standard deviation otherwise indicated.
b P value for the difference between the trial sample and target population was calculated by t test for age and χ2 test for other categorical variables.