Social cognitive theory mediators of physical activity in a lifestyle program for cancer survivors and carers: findings from the ENRICH randomized controlled trial.

BACKGROUND: Despite increasing numbers of cancer survivors and evidence that diet and physical activity improves the health of cancer survivors, most do not meet guidelines. Some social cognitive theory (SCT)-based interventions have increased physical activity behavior, however few have used objective physical activity measures. The Exercise and Nutrition Routine Improving Cancer Health (ENRICH) randomized controlled trial reported a significant intervention effect for the primary outcome of pedometer-assessed step counts at post-test (8-weeks) and follow-up (20-weeks). The aim of this study was to test whether the SCT constructs operationalized in the ENRICH intervention were mediators of physical activity behavior change. METHODS: Randomized controlled trial with 174 cancer survivors and carers assessed at baseline, post-test (8-weeks), and follow-up (20-weeks). Participants were randomized to the ENRICH six session face-to-face healthy lifestyle program, or to a wait-list control. Hypothesized SCT mediators of physical activity behavior change (self-efficacy, behavioral goal, outcome expectations, impediments, and social expectations) were assessed using valid and reliable scales. Mediation was assessed using the Preacher and Hayes SPSS INDIRECT macro. RESULTS: At eight weeks, there was a significant intervention effect on behavioral goal (A = 9.12, p = 0.031) and outcome expectations (A = 0.25, p = 0.042). At 20 weeks, the intervention had a significant effect on self-efficacy (A = 0.31, p = 0.049) and behavioral goal (A = 13.15, p = 0.011). Only changes in social support were significantly associated with changes in step counts at eight weeks (B = 633.81, p = 0.023). Behavioral goal was the only SCT construct that had a significant mediating effect on step counts, and explained 22 % of the intervention effect at 20 weeks (AB = 397.9, 95 % CI 81.5-1025.5). CONCLUSIONS: SCT constructs had limited impact on objectively-assessed step counts in a multiple health behavior change intervention for cancer survivors and their carers. Behavioral goal measured post-intervention was a significant mediator of pedometer-assessed step counts at 3-months after intervention completion, and explained 22 % of the intervention effect. Future research should examine the separate impact of goals and planning, as well as examining mediators of behavior maintenance in physical activity interventions targeting cancer survivors. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials registry ANZCTRN1260901086257 .

Impact of a nutrition and physical activity intervention (ENRICH: Exercise and Nutrition Routine Improving Cancer Health) on health behaviors of cancer survivors and carers: a pragmatic randomized controlled trial.

BACKGROUND: Physical activity and consuming a healthy diet have clear benefits to the physical and psychosocial health of cancer survivors, with guidelines recognising the importance of these behaviors for cancer survivors. Interventions to promote physical activity and improve dietary behaviors among cancer survivors and carers are needed. The aim of this study was to determine the effects of a group-based, face-to-face multiple health behavior change intervention on behavioral outcomes among cancer survivors of mixed diagnoses and carers. METHODS: The Exercise and Nutrition Routine Improving Cancer Health (ENRICH) intervention was evaluated using a two-group pragmatic randomized controlled trial. Cancer survivors and carers (n = 174) were randomly allocated to the face-to-face, group-based intervention (six, theory-based two-hour sessions delivered over 8 weeks targeting healthy eating and physical activity [PA]) or wait-list control (after completion of 20-week data collection). Assessment of the primary outcome (pedometer-assessed mean daily step counts) and secondary outcomes (diet and alcohol intake [Food Frequency Questionnaire], self-reported PA, weight, body mass index, and waist circumference) were assessed at baseline, 8-and 20-weeks. RESULTS: There was a significant difference between the change over time in the intervention group and the control group. At 20 weeks, the intervention group had increased by 478 steps, and the control group had decreased by 1282 steps; this represented an adjusted mean difference of 1761 steps (184 to 3337; P = 0.0028). Significant intervention effects for secondary outcomes, included a half serving increase in vegetable intake (difference 39 g/day; 95 % CI: 12 to 67; P = 0.02), weight loss (kg) (difference -1.5 kg; 95 % CI, -2.6 to -0.3; P = 0.014) and change in body mass index (kg/m(2)) (difference -0.55 kg/m(2); 95 % CI, -0.97 to -0.13; P = 0.012). No significant intervention effects were found for self-reported PA, total sitting time, waist circumference, fruit, energy, fibre, alcohol, meat, or fat consumption. CONCLUSIONS: The ENRICH intervention was effective for improving PA, weight, body mass index, and vegetable consumption even with the inclusion of multiple cancer types and carers. As an example of successful research translation, the Cancer Council NSW has subsequently adopted ENRICH as a state-wide program. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Register identifier: ANZCTRN1260901086257.