Purpose: To examine the relationship between intervention dose and health behavior change in Healthy Directions-Health Centers, an intervention designed to reduce cancer risk factors. DESIGN. Analysis of intervention condition participant data from a randomized controlled trial.
Setting: Community health centers in Massachusetts.
Subjects: Patients residing in low-income, working-class, multiethnic neighborhoods.
Intervention: Components were clinician endorsement, in-person counseling session and four telephone counseling sessions with a trained health advisor, and social-contextual tailored materials.
Measures: Intervention dose was number of six possible intervention components completed by each participant. Changes in fruit and vegetable consumption, red meat consumption, physical activity, and multivitamin intake between baseline (n=1088) and 8-month follow-up (n=967; 89% of baseline sample) were determined.
Analysis: Bivariate and multivariate associations between intervention dose and change in health behaviors were examined.
Results: In multivariate analysis, the association between intervention dose and increase in multivitamin intake approached significance (p < .07). Seventy percent of participants completed all intervention activities. In bivariate analysis, completion of four telephone counseling calls was associated with decrease in red meat consumption (p < .05).
Conclusion: These findings indicate that future studies should examine the number, content, and length of contacts needed for behavior change. The results also suggest that health centers are a channel for reaching diverse populations, as shown by the high level of intervention implementation.