Table 4.

Statistically significant results from multiple linear regression analysis (backward procedure). Dependent variables were the concentrations of C-reactive protein (CRP), club cell protein 16 (CC-16) and surfactant protein D (SP-D) at baseline. Independent variables were exposure category (Expo) (0/1), age (years), infection (0/1), body mass index (BMI) (kg/m²), sampling time (minutes since midnight) and current tobacco smoking (0/1). Beta-coefficients and corresponding p-values are presented.

Biomarkers	Expo	Age	BMI	Smoking	Sampling Time	Infection	Mult. r
CRP (mg/L) †	-	0.008 *	0.04 ***	-	-	0.28 **	0.45 ***
SP-D (µg/L) †	-	-	-	-	-	-	No model
CC-16 (µg/L)	-	-	-	−0.73 *	−0.004 ***	-	0.45 ***

^† variable transformed to lg; *** p < 0.001; ** p < 0.01; * p < 0.05.