Table 3.

Association of BDR categories at enrollment with drop in FEV₁ between baseline and follow-up visit and respiratory exacerbations in subjects with chronic obstructive pulmonary disease

	Change in FEV1 (n = 1,702) (ml/yr)		Exacerbations (n = 2,980)		Severe Exacerbations (n = 2,980)
	Coef (95% CI)	P Value	IRR (95% CI)	P Value	IRR (95% CI)	P Value
No-BDR	Ref		Ref		Ref
FEV1-BDR	−18.34 (−28.78 to −7.90)	<0.001	1.18 (0.90 to 1.55)	0.26	0.97 (0.68 to 1.40)	0.88
FVC-BDR	−8.11 (−15.49 to −0.73)	0.03	1.10 (0.93 to 1.30)	0.29	1.09 (0.88 to 1.35)	0.42
Combined-BDR	−21.86 (−29.60 to −14.11)	<0.001	1.25 (1.03 to 1.50)	0.02	1.34 (1.05 to 1.71)	0.02
ATS-BDR*	−15.32 (−20.66 to −9.98)	<0.001	1.16 (1.02 to 1.32)	0.02	1.16 (0.98 to 1.37)	0.08

Definition of abbreviations: ATS = American Thoracic Society; ATS-BDR = increase in prebronchodilator FEV₁ and/or FVC ≥12% and ≥200 ml after bronchodilator administration; BDR = bronchodilator response; CI = confidence interval; Coef = coefficient; Combined-BDR = an increase in both FEV₁ and FVC ≥12% and ≥200 ml after bronchodilator administration; FEV₁ = forced expiratory volume in 1 second; FEV₁-BDR = increase in FEV₁ ≥12% and ≥200 ml but a change in FVC <12% and 200 ml after bronchodilator administration; FVC = forced vital capacity; FVC-BDR = increase in FVC ≥12% and ≥200 ml but a change in FEV₁ <12% and 200 ml after bronchodilator administration; IRR = incidence rate ratio; No-BDR = a change in both FEV₁ and FVC <12% and <200 ml after bronchodilator administration.

All models included the following covariates: age, sex, race, smoking status, smoking pack-years, body mass index, and post-bronchodilator FEV₁% predicted.

^*Multivariable logistic regression models with ATS-BDR binary variable = BDR according to ATS guidelines; Yes or No as the independent variable.