Table 4.

Sobel–Goodman mediation tests with Year 15 early life stress as independent variable, Year 20 sickness behavior symptoms as dependent variables, and Year 20 IL-6 as mediating variable

Sickness behavior symptom	Model with IV and DV		Model with IV, DV and MV		% mediated by IL-6	P	% mediated by IL-6 after adjustment*	P
	Beta	P	Beta	P
Fatigue	0.138	<0.001	0.133	<0.001	3.2	0.014	2.3	0.072
Pain	0.115	<0.001	0.107	<0.001	6.3	0.004	4.2	0.059
Sleep disturbance	0.126	<0.001	0.122	<0.001	3.2	0.019	1.2	0.191
Depression†	0.254	<0.001	0.249	<0.001	2.0	0.009	0.8	0.120

IL-6 = interleukin-6; IV = independent variable; DV = dependent variable; MV = mediating variable; Beta = standardized regression coefficient expressing the change in standardized outcome score per one standard deviation in early life stress measured as Early Family Environment

^*Adjusted for sociodemographic variables (age, gender, ethnicity, and education)

Center for Epidemiological Studies Depression Scale (CES-D) score excluding 2 fatigue items and 1 sleep item