Risk factors for loss to follow-up	Odds Ratio
Male	1.24(1.16-1.33)
Age
21-35	1.0
36-45	0.65(0.59-0.71)
46-55	0.39(0.36-0.42)
Education
Elementary	1.0
Upper secondary and certificate	0.80(0.72-0.88)
University/college	0.53(0.48-0.59)
Other/missing	0.85(0.70-1.04)
Smoking habits
Never	1.0
Past	1.00(0.92-1.09)
Current	1.32(1.22-1.44)
Reduced workability	1.27(1.16-1.39)
Employed last 12 months	0.86(0.78-0.94)
Physician diagnosed asthma	1.13(1.01-1.25)
Woke up with chest tightness last 12 months	1.13(1.02-1.25)
COPD	1.43(1.02-2.00)