Table 2.

Distribution of Nrf2, IL-6, SP-D, and CRP levels in each group

	Control	COPD-stable	COPD-exacerbation	Shapiro-Wilk	Levene’s test	p value	Jonckheere-Terpstra p value
Nrf2, ng/mL	12.71 ± 2.08	14.08 ± 1.87	15.22 ± 3.05	0.06	0.06	0.006a	0.002
IL-6, pg/mL	10.62 ± 5.20	12.34 ± 6.85	25.58 ± 32.19	< 0.001	< 0.001	0.653b	-
SP-D, pg/mL	85.13 ± 41.45	102.32 ± 70.01	162.03 ± 128.73	< 0.001	< 0.001	0.124b	-
CRP, mg/dL	1.55 ± 3.26	2.87 ± 4.14	5.15 ± 6.17	< 0.001	0.080	0.001b	< 0.001

Values are presented as mean ± SD.

Nrf2, nuclear factor erythroid 2-related factor 2; IL-6, interleukin 6; SP-D, surfactant protein D; CRP, C-reactive protein; COPD, chronic obstructive pulmonary disease.

^aAnalysis of variance.

^bKruskal-Wallis test.