Circulating surfactant protein D as a potential lung-specific biomarker of health outcomes in COPD: a pilot study

BMC Pulmonary Medicine

Table 4 Association between the changes in serum protein biomarkers, lung function, dyspnea score and total CRQ scores over 3 months

	Change in SPD*			Change in CC16*			Change in CRP*			Change in distance^†
	β	R	P	β	R	P	β	R	P	β	R	P
Change in Dyspnea Score	-1.95 (-1.95)	0.56 (0.56)	0.018 (0.018)	-1.33 (-1.55)	0.24 (0.28)	0.359 (0.185)	0.42 (0.19)	0.23 (0.10)	0.367 (0.626)	-14.63 (-16.91)	0.46 (0.52)	0.063 (0.032)
Change in CRQ Score	-1.50 (-1.13)	0.61 (0.44)	0.010 (0.008)	-1.52 (-2.01)	0.38 (0.49)	0.135 (0.011)	-0.14 (-0.35)	0.10 (0.26)	0.688 (0.214)	-15.67 (-15.67)	0.36 (0.36)	0.163 (0.163)
Change in SPD*		--	--	0.64 (0.64)	0.39 (0.39)	0.119 (0.119)	0.15 (0.15)	0.29 (0.08)	0.261 (0.261)	3.05 (3.05)	0.03 (0.03)	0.916 (0.916)
Change in CC16*		--	--		--	--	0.10 (0.10)	0.30 (0.30)	0.248 (0.182)	61.38 (88.51)	0.35 (0.46)	0.175 (0.611)
Change in CRP*										-5.81 (-5.81)	0.10 (0.10)	0.698 (0.698)

* Logarithmic scale.
† Change in the distance of six-minute walk test (m).
Values in brackets were derived from a stepwise regression model in which age, sex, body mass index, PO₂, PCO₂ and FEV₁ were included in the model.
Abbreviations: CC16 – Clara cell protein 16, CRP – C-reactive protein, CRQ – Chronic Respiratory Disease Questionnaire, SPD – surfactant protein D.

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