Table 1– Baseline characteristics of the screen and control group responders included in the health-related quality of life study of the Dutch–Belgian Randomised Controlled Lung Cancer Screening Trial (NELSON trial)

	Screen group^#	Control group^¶
Subjects n	665	460
Males	46.2	50.0
Age yrs	57.8±5.5	57.8±5.7
Education
Primary education	9.8	11.5
Lower vocational or lower secondary general education	38.0	37.6
Intermediate vocational or higher secondary general education	25.2	23.3
Higher vocational education or university education	27.1	27.6
Smoking
Current smokers	53.7	52.4
Pack-yrs	39.7±17.4	39.4±16.2

Data are presented as mean±sd or %, unless otherwise stated. No significant differences were observed between the screen and control groups (Chi-squared and Mann–Whitney U-tests). ^#: subjects received both the T0 (before trial randomisation) and T2 (1.5 yrs after baseline screening) questionnaire and responded to at least one; excluded subjects did not respond to T0 and T2 (n = 17), had computed tomography (CT) scans but were off-study at T2 (n = 23), and did not undergo CT scans (n = 28). ^¶: subjects received both the T0 and T2 questionnaire and responded to at least one; excluded subjects did not respond to T0 and T2 (n = 38), were off-study at T2 (n = 7), and were not selected in the random sample (n = 228).