Reproducibility and Validity of a Food Intake Survey Developed for Implementation via Digital Health for Patients With or at Risk for Cardiovascular Disease.

Background: We developed the SaFIS, a structured self-administered food intake survey for patients with cardiovascular diseases needing dietary improvements. Methods and Results: The SaFIS comprised questions on 31 items, including staple foods (7 items) and food ingredients (24 items), based on the foods recommended by the Japanese Atherosclerosis Society for the Prevention of Arteriosclerotic Disease. To evaluate reproducibility, SaFIS was administered twice with a 1-month interval using the intraclass correlation coefficient (ICC [1,1]). Validity was assessed by comparing energy and nutrient content from a weighed dietary record (WDR) with the first SaFIS survey using Bland-Altman plots. Reproducibility values were energy (ICC 0.90, 95% confidence interval: 0.80-0.95), protein (0.90, 0.80-0.95), fat (0.76, 0.54-0.88), saturated fatty acids (0.78, 0.58-0.89), monounsaturated fatty acids (0.76, 0.56-0.88), polyunsaturated fatty acids (0.82, 0.66-0.91), carbohydrates (0.89, 0.79-0.95), and dietary fiber (0.86, 0.71-0.93). Bland-Altman values indicated SaFIS-based energy, protein, carbohydrate, monounsaturated fatty acids, and dietary fiber were 67.2 kJ, 5.7 g, 3.9 g, 0.5 g, and 1.8 g greater than WDR-based values, respectively. SaFIS-based fat, saturated, and polyunsaturated fatty acid values were 0.7 g, 1.3 g, and 0.39 g less than WDR-based values, respectively. Conclusions: SaFIS demonstrated high reproducibility and validity with clinical potential. Subsequent introduction to digital health from the usability perspective is planned.