Educational attainment, health locus of control and inflammation among cancer survivors in the Midlife in the United States (MIDUS) study

The goal of this study was to investigate whether HLOC mediates the relationship between educational attainment and inflammatory proteins in cancer survivors. Data are from 298 cancer survivors (87.54% white; M age = 63.6; M survivorships = 15 years) who participated in the Biomarker protocol of Wave 2 and Refresher phases of the Midlife in the United States (MIDUS) study. Educational attainment was dichotomized (bachelor’s degree or above versus lower). The two measures of HLOC were based on whether participants felt others had control over their health outcomes (external HLOC) or if they felt they were in control of their health outcomes (internal HLOC). We used C-reactive protein (CRP) and interleukin-6 (IL-6) as markers of inflammation. Mediation analyses for external and internal HLOC were tested separately. Mediation analyses were conducted using the PROCESS package in R (using 10 000 bootstrapped samples). Analyses were adjusted for age, sex, cohort, body mass index (BMI), smoking status, and race/ethnicity. In the fully adjusted model, educational attainment and external HLOC were significantly associated with CRP. Relative to those with bachelor’s degrees, participants with lower educational attainment had elevated CRP (b = -0.25, SE = 0.11, 95% CI = [−0.47, −0.03]). Higher external HLOC was linked to increased CRP (b = 0.10, SE = 0.04, 95% CI = [0.01, 0.18]). The mediation analyses showed that a higher external HLOC was a significant path through which lower educational attainment was associated with elevated CRP (indirect effect = -0.05, bootstrapped SE = 0.02, 95% CI [bootstrapped] = [−0.10, −0.01]. Cancer survivors with lower educational attainment may tend to perceive that their health is outside of their control. These socioeconomic and psychosocial processes may drive an increase in the circulating levels of inflammatory signaling proteins known to be sensitive predictors of age-related chronic diseases.