Clinical characteristics of airway impairment assessed by impulse oscillometry in patients with chronic obstructive pulmonary disease: findings from the ECOPD study in China

Table 3 Associations between acute exacerbations of COPD in the previous year and airway impairment in patients with chronic obstruction pulmonary disease

AECOPD in the previous year	With airway impairment	Without airway impairment	Risk ratio (95%CI) ^#	P value
Total—per patient-year	R₅ > ULN (n = 459)	R₅ ≤ ULN (n = 308)
	0.18 (0.07)	0.11 (0.05) ^†	1.58 (1.13–2.19)	0.007
Total—per patient-year	R₂₀ > ULN (n = 228)	R₂₀ ≤ ULN (n = 539)
	0.16 (0.06)	0.17 (0.07)	0.93 (0.67—1.29)	0.661
Total—per patient-year	R₅-R₂₀ > ULN (n = 480)	R₅-R₂₀ ≤ ULN (n = 287)
	0.19 (0.07)	0.11 (0.04) ^†	1.73 (1.22—2.45)	0.002
Total—per patient-year	X₅ < LLN (n = 406)	X₅ ≥ LLN (n = 361)
	0.19 (0.07)	0.09 (0.04) ^†	2.11 (1.51–2.95)	< 0.001
Total—per patient-year	AX > ULN (n = 468)	AX ≤ ULN (n = 299)
	0.18 (0.07)	0.08 (0.03) ^†	2.20 (1.53–3.16)	< 0.001
Total—per patient-year	F_res > ULN (n = 516)	F_res ≤ ULN (n = 251)
	0.18 (0.07)	0.08 (0.04) ^†	2.13 (1.44–3.15)	< 0.001

Datas are presented as means (standard error)
The number of acute exacerbation of COPD per patient-year was the number of times of exacerbation for a single patient per year
^#After adjusting for age, sex, BMI, smoking index, smoking status, family history of respiratory diseases, occupational exposures, biomass exposure, and history of asthma, Poisson regression was applied to analyze the associations between acute exacerbations of COPD (AECOPD) in the previous year and airway impairment. CI, confidential interval. ^†: p < 0.05; Bold values represent signifificant p values.

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