Moderating Effects of Social Determinants of Health on Quality of Life in Expressive Writing Interventions Among Chinese American Breast Cancer Survivors

OBJECTIVE: Chinese American breast cancer survivors (CABCS) often face cultural challenges regarding emotional expression. Expressive writing (EW) interventions can improve emotional expression and, thus, quality of life (QOL), but individual responses to EW may vary. We examined whether specific social determinants of health (SDOH)-personal income, education, employment status, and marital status-moderated the effect of EW on QOL among CABCS. METHODS: A three-arm randomized controlled trial of EW was conducted among CABCS (N = 136). Conditions were self-regulation (SR; emotions, coping, positivity), enhanced self-regulation (ESR; coping, emotions, positivity), and cancer facts (control). Participants completed three weekly writing sessions. Separate residual change regressions were performed to examine interactions between intervention condition and each of the four SDOH variables on 6-month QOL, controlling for covariates and baseline QOL. RESULTS: Income significantly moderated intervention efficacy at the 6-month follow-up, with exploratory evidence also suggesting moderation by marital status. In the ESR condition, participants with above poverty-level income (≥ $15,000) reported higher QOL than those with poverty-level income (< $15,000; b = 7.66, p = 0.037). Among participants with above poverty-level income, the ESR group reported significantly higher QOL than participants in the control group (b = 15.16, p < 0.001). In an exploratory finding, among unmarried participants, those in the SR condition had higher QOL than those in the control (b = 12.09, p = 0.038). CONCLUSIONS: EW interventions can improve QOL among CABCS, but their efficacy may depend on individual SDOH factors. These findings suggest that culturally tailored interventions accounting for survivors' SDOH may enhance EW's therapeutic impact. TRIAL REGISTRATION: The trial is registered at ClinicalTrials.gov (Identifier: NCT02946619).