Long-term outcomes of the FRESH START trial: exploring the role of self-efficacy in cancer survivors' maintenance of dietary practices and physical activity

Abstract

Background: This study examined whether changes in self-efficacy explain the effects of a mailed print intervention on long-term dietary practices of breast and prostate cancer survivors. The relationship between change in self-efficacy and long-term physical activity (PA) also was examined.

Methods: Breast and prostate cancer survivors (N = 543) from 39 US states and two Canadian provinces participated in the FRESH START intervention trial. Participants were randomly assigned to receive a 10-month program of mailed print materials on diet and PA available in the public domain or a 10-month program of tailored materials designed to increase fruit and vegetable (F&V) intake, decrease fat intake, and/or increase PA. Changes in self-efficacy for F&V intake and fat restriction were analyzed as potential mediators of the intervention's effects on diet at 2-year follow-up. Because we previously found that change in self-efficacy for PA did not vary by group assignment, the relationship between change in self-efficacy and PA at 2-year follow-up was examined across study conditions.

Results: Results suggest that change in self-efficacy for fat restriction partially explained the intervention's effect on fat intake (mean indirect effect = -0.28), and change in self-efficacy for F&V consumption partially explained the intervention's effect on daily F&V intake (mean indirect effect = .11). Change in self-efficacy for fat restriction partially accounted for the intervention's impact on overall diet quality among men only (mean indirect effect = 0.60). Finally, change in self-efficacy for PA predicted PA at 2-year follow-up.

Conclusions: Findings suggest that self-efficacy may influence long-term maintenance of healthy lifestyle practices among cancer survivors.

Figures 1a and 1b

Models depicting the effects of intervention condition (coded 0 = attention control, 1 = FRESH START intervention) on dietary outcomes at year 2 and mediators at year 1, adjusting for baseline mediator and dependent variables. Unstandardized regression coefficients are reported. Standard errors are in parentheses. The coefficient in brackets is from the model that did not include the mediator. Self-efficacy scores range from 1 to 5 with higher scores indicating greater self-efficacy. F&V = fruits and vegetables. **p < .01. ***p < .001.

Figure 2

Model depicting the effects of intervention condition (coded 0 = attention control, 1 = FRESH START intervention) on diet quality at year 2 and mediators at year 1, adjusting for baseline mediator and dependent variables. Unstandardized regression coefficients are reported. Standard errors are in parentheses. The coefficient in brackets is from the model that did not include the mediator. Self-efficacy scores range from 1 to 5 with higher scores indicating greater self-efficacy. Diet quality scores range from 0 to 100 with higher scores indicating better diet quality. F&V = fruits and vegetables. *p < .05. **p < .01. ***p < .001.