Diet quality in an ethnically diverse population of older men in Australia

To compare the Australian Dietary Guideline Index (DGI-2013) and the Pyramid-based Mediterranean Diet Score (pyrMDS) as measures of diet quality in an ethnically diverse group of older men.

Seven hundred and ninety-four older men aged ≥75 participated in wave 3 (2012-2013) of the Concord Health and Ageing in Men Project. Dietary intake was assessed using a validated diet history questionnaire. Ethnicity was based on self-reported country of birth and categorised as Australian-born (418 men), Italian or Greek migrants (188), and other migrants (188). Incident cardiovascular outcomes until March 2018 were measured using the composite of major adverse cardiovascular events (MACE), which comprises all-cause mortality, acute myocardial infarction, congestive cardiac failure, coronary revascularisation and/or ischaemic stroke. Ability to predict incident cardiovascular outcomes and all-cause mortality were compared between standardised DGI-2013 pyrMDS scores by comparison of hazard ratios, discrimination (Harrell's C-statistic) and calibration (calibration plots).

Italian and Greek migrant men had significantly lower DGI-2013 scores (91.7 vs. 93.9; p = 0.01) but significantly higher pyrMDS scores (8.8 vs. 8.2; p < 0.0001) than Australian-born men. In the whole sample (794 men), the pyrMDS was a better predictor of both MACE (age-adjusted HR = 0.84; 95% CI = 0.75-0.94 vs. HR = 0.92; 95% CI = 0.82-1.03 for DGI-2013) and all-cause mortality (age-adjusted HR = 0.69; 95% CI = 0.60-0.80 vs. HR = 0.86; 95% CI = 0.74-0.99). The pyrMDS also demonstrated superior discrimination for predicting all-cause mortality and superior calibration for MACE and all-cause mortality.

The DGI-2013 appears to underestimate diet quality in older Italian and Greek migrant men. The pyrMDS appears superior to the DGI-2013 for prediction of incident cardiovascular disease and mortality regardless of ethnic background.