Self-rated quality of life measures: Effect of change to a low-fat, high-fiber, fruit and vegetable enriched diet

The Polyp Prevention Trial (PPT) was a multicenter, randomized clinical trial to determine the effect of a low-fat (20% of energy from fat), high-fiber (18 g/1000 kcal/day), high-fruit/vegetable (3.5 servings/1000 kcal/day) eating plan on the recurrence of large bowel adenomatous polyps. The PPT provided an opportunity to examine the impact of dietary changes on quality of life. At baseline and annually for 4 years, participants in the Quality of Life Substudy of PPT completed a Quality of Life Factors (QF) Questionnaire, a modified Block-National Cancer Institute Food Frequency Questionnaire, and a Health and Lifestyle Questionnaire. The 51-item QF Questionnaire assessed changes in nine domains: taste, convenience, cost, self-care, social, health assessment, health belief, health action, and life satisfaction. The analysis compared annual changes in domain scores for intervention (n = 194) and control (n = 200) participants. At Year 1, 363 (92%) completed a questionnaire, and 325 (82%) participants completed a Year 4 questionnaire. There were no statistically significant differences between treatment groups in the change from baseline to Year 1 for the convenience, cost, taste, health assessment, and life satisfaction domains. At Year 1, intervention participants rated the self-care (p <. 001), health belief (p =. 021), and health action (p <. 001) domains significantly higher and the social domain significantly lower (p <. 001) than control participants. These changes were consistent through Years 2, 3, and 4. This study provides evidence that, given appropriate support, free-living individuals can successfully alter their eating patterns in multiple ways without a negative impact on quality of life.