Validity and Reliability of a Brief Dietary Assessment Questionnaire in a Cardiac Rehabilitation Program

Purpose: Dietary assessment is vital to inform individualized nutrition care and to evaluate the success of interventions aimed at improving diet for participants in cardiac rehabilitation (CR) programs. The purpose of this study was to assess the validity and reliability of an instrument developed to reflect current evidence-informed dietary recommendations advocated to reduce cardiovascular risk. Methods: This study was conducted at a single CR program at the University of North Carolina, Chapel Hill. Two dietary assessments were administered: Picture Your Plate (PYP) and a reference instrument, the Harvard/Willett Food Frequency Questionnaire (HWFFQ). The PYP is a modification of a previously validated instrument, the Dietary Risk Assessment-New Leaf (DRA-New Leaf). Concurrent validity was assessed by comparing the PYP total score with 3 diet quality indexes (Alternative Health Eating Index [AHEI], Dietary Approaches to Stop Hypertension [DASH], and Alternative Mediterranean Diet [aMED]) calculated from the HWFFQ and by assessment of agreement in tertile cross-classification. An intraclass correlation (ICC) was calculated to assess test-retest reliability. Results: Among the 108 participants, crude and adjusted Spearmen correlation coefficients between the PYP and 3 indexes of dietary quality were AHEI-2010 (0.71-0.72), DASH (0.70-0.71), and aMED (0.52-0.58) (P< .0001, all comparisons). Agreement of tertiles comparing PYP and AHEI-2010 was 67% and the score in opposite tertiles was 6%. The weighted kappa value (kappa w) = 0.71. The test-retest ICC was 0.91 (95% CI, 0.85-0.93; n = 91). Conclusions: Results support the PYP as a valid and reliable dietary assessment tool for use in CR programs. Continued research in additional CR program populations is recommended.