	Postbronchodilator FEV₁% predicted			Postbronchodilator FEV₁% predicted
	Coef (95% CI)	P value	AIC	Coef (95% CI)	P value	AIC
Exacerbations	−0.011 (−0.012 to 0.01)	<0.001	−1233	−0.011 (−0.01 to 0.0097)	<0.001	−1222
Severe exacerbations	−0.004 (−0.0045 to 0.0036)	<0.001	−11787	−0.004 (−0.0045 to 0.0036)	<0.001	−11777
Change in FEV₁, mL	−1.91 (−2.28 to 1.53)	<0.001	54 218	−2.76 (−3.13 to 2.39)	<0.001	54 112
Change in MMRC	−0.002 (−0.0038 to 0.00065)	0.006	1996	−0.02 (−0.0036 to 0.00037)	0.016	1998
Change in SGRQ	−0.01 (−0.03 to 0.0095)	0.32	26 415	−0.01 (−0.029 to 0.01)	0.34	26 415
Change in 6-MWD, feet	0.99 (0.53 to 1.46)	<0.001	55 749	0.9 (0.43 to 1.37)	<0.001	55 753

All regression models included the following covariates: age, sex, race, smoking status, pack per years, history (per questionnaire) of asthma, diabetes, high blood pressure, stroke and sleep apnoea.
6-MWD, 6 min walk distance; AIC, Akaike information criterion; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; MMRC, modified Medical Research Council dyspnoea score; SGRQ, St. George’s Respiratory Questionnaire score.