Factor analysis in the identification of dietary patterns and their predictive role in morbid and fatal events

OBJECTIVE: The purpose was to examine the role of dietary patterns derived from factor analysis and their association with health and disease.

DESIGN: Longitudinal population study, with measurement of diet (dietary history method), cardiovascular risk factors and a follow-up of 20 years for CHD incidence and 40 years for mortality.

SETTING: Two population samples in rural villages in northern and central Italy.

SUBJECTS: Men (n 1221) aged 45-64 years were examined and followed up.

RESULTS: One of the factors identified with factor analysis, run on seventeen food groups, was converted into a factor score (Factor 2 score) and used as a possible predictor of morbid and fatal events. High values of Factor 2 score were characterized by higher consumption of bread, cereals (pasta), potatoes, vegetables, fish and oil and by lower consumption of milk, sugar, fruit and alcoholic beverages. In multivariate analysis, Factor 2 score (mean 0·0061; sd 1·3750) was inversely and significantly associated (hazard ratio for a 1 sd increase; 95% CI) with 20-year CHD incidence (0·88; 0·73, 0·96) and 40-year mortality from CHD (0·79; 0·66, 0·95), CVD (0·87; 0·78, 0·96), cancer (0·84; 0·74, 0·96) and all causes (0·89; 0·83, 0·96), after adjustment for five other risk factors. Men in quintile 5 of Factor 2 score had a 4·1 years longer life expectancy compared with men in quintile 1.

CONCLUSIONS: A dietary pattern derived from factor analysis, and resembling the characteristics of the Mediterranean diet, was protective for the occurrence of various morbid and fatal events during 40 years of follow-up.