Table 4. Multiple linear regression analyses using FEV1/FVC as a dependent variable in younger and elderly groups.

	Younger group			Elderly group
	β	p	95%CI	β	p	95%CI
Age (1 year increase)	−0.103	0.147	−0.243 to 0.037	0.119	0.373	−0.152 to 0.390
Gender (male)	2.263	0.028	0.255 to 4.272	−0.027	0.992	−5.313 to 5.259
BMI (1 kg/m2 increase)	−0.006	0.972	−0.322 to 0.311	−0.138	0.657	−0.778 to 0.502
TG (1 mg/dl increase)	−0.028	<0.001	−0.042 to −0.014	0.040	0.064	−0.003 to 0.082
WBC (1/μl increase)	0.001	0.001	0.001 to 0.002	0.001	0.409	−0.001 to 0.002
Smoking (1 pack-year increase)	−0.049	0.381	−0.158 to 0.061	−0.203	0.002	−0.324 to −0.082
SAF (1 AU increase)	1.759	0.332	−1.815 to 5.333	−5.862	0.009	−10.132 to −1.592
	r	0.411		r	0.683
	r2	0.169		r2	0.466

FEV1: force expiratory volume in one second; FVC: forced vital capacity; BMI: body mass index; TG: triglyceride; WBC: white blood cell; SAF: skin autofluorescence; AU: arbitray units.