Moderators Of A Multi-Component Physical Activity Behavior Change Intervention Effects On Fatigue, Depression, And Anxiety

Abstract

BACKGROUND: Fatigue, depression, and anxiety significantly reduce quality of life in breast cancer survivors (BCS). Identifying factors that predict symptom response to physical activity (PA) behavior change interventions may allow for more targeted interventions. PURPOSE: To determine demographic and medical factors that moderate the effects of a multi-component PA behavior change intervention (i.e., BEAT Cancer) on fatigue, depressive symptomatology, and anxiety in BCS. METHODS: In this multi-center randomized controlled trial, post-primary treatment BCS (N=222; Stage 0-III) were assigned to BEAT Cancer PA intervention or usual care (i.e., PA-related written materials) Fatigue Symptom Inventory (11-point, Likert scale (0=best; 10=worst) and Hospital Anxiety and Depression Scale were assessed at baseline, 3 months (immediately post-intervention) and 6 months. Moderators (baseline value of each outcome, age, income, marital status, cancer stage, months since diagnosis, cancer treatment, body mass index [BMI], and comorbidities) were assessed at baseline (BMI measured on-site; remaining factors self-reported). This study is a post-hoc exploratory analysis using linear regression to test hypothesized moderators. RESULTS: Participants with baseline fatigue interference ≥3 experienced greater improvements in fatigue interference (p = .020; -1.35 vs. -.42 for interference <3). Those with a history of radiation experienced greater reductions in depressive symptomatology (p = .013; -1.53 vs. 0.08 if no history of radiation). Finally, participants with <2 comorbidities or BMI <30 experienced greater reductions in anxiety (p = .010; -1.97 vs. -.26 for ≥ 2 comorbidities and p = .033; -1.66 vs. -.33 for BMI ≥ 30, respectively). No statistically significant moderators of the intervention effects on fatigue intensity were found. CONCLUSIONS: Findings indicate that BCS with higher baseline fatigue interference, history of radiation, <2 comorbidities, and BMI <30 may have a more favorable symptom response with a PA behavior change intervention. Future research is needed to identify etiologic mechanisms for lack of response (e.g., radiation therapy) and unmet needs of less responsive subgroups (e.g., multiple comorbidities, obesity).