Table 4.

Annual rate of post-bronchodilator FEV₁ decline in subjects meeting the lower limit of normal criterion

	Unadjusted		Adjusted
	Mean ± SE	P-value	Mean ± SE	P-value
According to median age
FEV1, mL/year
Younger	−11.79±3.64	0.053	−13.17±4.19	0.062a
Older	−21.83±3.68		−23.15±4.13
FEV1, %/year
Younger	−0.39±0.12	0.017	−0.40±0.15	0.039b
Older	−0.80±0.12		−0.83±0.14
According to age quartile
FEV1, mL/year
Q1	−10.62±5.22	0.113	−11.11±6.03	0.085a
Q2	−12.87±5.05		−13.17±5.79
Q3	−17.40±4.80		−16.67±5.47
Q4	−28.12±5.70		−31.43±6.28
FEV1, %/year
Q1	−0.33±0.17	0.021	−0.34±0.21	0.023b
Q2	−0.50±0.17		−0.46±0.20
Q3	−0.60±0.16		−0.55±0.19
Q4	−1.08±0.19		−1.20±0.22

Notes:

^aThe numbers and ages of patients within each quartile group were as follows: Q1 (n=107, below 62 years), Q2 (n=115, 62–67 years), Q3 (n=133, 67–72 years), and Q4 (n=126, above 72 years). Adjusted for sex, body mass index, smoking status, bronchodilator response, experience of acute exacerbation, and initial FEV₁.

^bAdjusted for smoking status, bronchodilator response, experience of acute exacerbation, and initial FEV₁.

Abbreviations: FEV₁, forced expiratory volume in 1-second; SE, standard error.