Dietary patterns in relation to quality-adjusted life years in the EPIC-NL cohort

Dietary patterns have been associated with the incidence or mortality of individual non-communicable diseases, but their association with disease burden has received little attention.

The aim of our study was to relate dietary patterns to health expectancy using quality-adjusted life years (QALYs) as outcome parameter.

Data from the EPIC-NL study were used, a prospective cohort study of 33,066 healthy men and women aged 20-70 years at recruitment. A lifestyle questionnaire and a validated food frequency questionnaire were administered at study entry (1993-1997). Five dietary patterns were studied: three a priori patterns (the modified Mediterranean Diet Score (mMDS), the WHO-based Healthy Diet Indicator (HDI) and the Dutch Healthy Diet index (DHD-index)) and two a posteriori data-based patterns. QALYs were used as a summary health measure for healthy life expectancy, combining a person's life expectancy with a weight reflecting loss of quality of life associated with having chronic diseases.

The mean QALYs of the participants were 74.9 (standard deviation 4.4). A higher mMDS and HDI were associated with a longer life in good health. Participants who had a high mMDS score (6-9) had 0.17 [95% CI, 0.05; 0.30] more QALYs than participants with a low score (0-3), equivalent to two months longer life in good health. Participants with a high HDI score also had more QALYs (0.15 [95% CI, 0.03; 0.27]) than participants with a low HDI score.

A Mediterranean-type diet and the Healthy Diet Indicator were associated with approximately 2months longer life in good health.