The Dietary Quality Score: validation and association with cardiovascular risk factors: the Inter99 study

Objective: To develop and assess the validity of the Dietary Quality Score (DQS) and investigate the association with cardiovascular risk factors. Design: Cross-sectional population-based study. Setting: Copenhagen County, Glostrup, Denmark. Subjects: A random sample of 12 934 men and women aged 30-60 years were invited to a health examination. A total of 6542 participants were included in the statistical analysis. Methods: The DQS was developed using eight questions from a 48-item food frequency questionnaire (FFQ) and validated using a 198-item FFQ. Associations between the DQS and fasting serum lipids, homocysteine, blood pressure and the absolute risk of ischaemic heart disease (IHD) were explored. Results: A higher DQS was shown to be associated with higher dietary quality in general, including a low intake of fat, especially saturated fat; a high intake of fibre; various vitamins and minerals; and fruit, fish, vegetables and whole-grain products. A higher score according to the DQS was significantly negatively associated with total cholesterol (P = 0.0031), triglyceride (P = 0.0406), low-density lipoprotein-cholesterol (P = 0.0071), homocysteine (P < 0.0001) and the absolute risk of IHD (P < 0.0001), adjusted for sex, age, smoking habits and physical activity level. Conclusions: The DQS is a simple, valid and quick tool to make a rough classification of individuals into groups with high, average and low dietary quality. The DQS is negatively associated with serum lipids, homocysteine and the absolute risk of IHD.