Process evaluation of a clinical preventive nutrition intervention

Background . We report process data on the feasibility of delivering a clinical preventive nutrition intervention that was effective in increasing participants' consumption of fruits and vegetables. We also examine relationships between process variables and study outcomes. Methods . We randomly assigned six practice sites in a managed care organization to a dietary intervention or control condition. We invited adults 18 years of age or older scheduled for routine health visits within the subsequent 2 months to participate. Of the 566 patients we contacted from the intervention sites, 230 (41%) enrolled. From the control sites, we contacted 617, and 274 (44%) enrolled. Intervention participants received a tailored letter providing feedback on their consumption of target foods together with recommendations for improvement, stage-matched nutrition education booklets, a diet-health endorsement from their primary care providers (PCPs), and two motivational counseling telephone calls. Of enrollees, 195 (85%) in the intervention group and 252 (92%) in the control group returned the final survey 3 months later. Results . Seventy-one percent of both participants and PCPs reported that the PCPs had discussed the relationship between diet and health at their visit. Fifty-seven percent of participants and 62% of PCPs reported that they discussed the complete diet-health endorsement, which included: (1) acknowledgment of the relationship between diet and health and (2) tailored study recommendations. The inclusion of both parts of the diet-health endorsement, but not the length of time spent, appeared to correlate with healthful outcomes. Conclusions . These process data suggest that the brief PCP diet-health endorsement contributed to the intervention effect on fruits and vegetables.