Practice Update: Diabetes

EDITOR’S PICKS 4

Improved Diet Quality Associated with Reduced Mortality The New England Journal of Medicine

Take-home message • Data from the Nurses’ Health Study and the Health Professionals Follow-Up Study were used to evaluate the association between changes in diet quality over 12 years and subsequent mortality risk. Individuals with the greatest improvement in diet quality had a significant decrease in risk of all-cause mortality compared with those with a relatively stable diet quality. There was a significant association between a 20-percentile increase in diet scores and a reduced risk of total and cardiovascular mortality. Maintenance of a good diet quality over the 12-year period was also associated with a lower risk of all-cause mortality. • Improvements in diet quality over time were associated with a significantly reduced mortality risk.

COMMENT By Thomas C Keyserling MD, MPH M ost lifestyle intervention stud- ies to reduce cardiovascular disease (CVD) focus on inter- mediate outcomes such as change in blood pressure, blood lipids, or weight. Few behavioral intervention studies have been large enough or conducted for a long enough period to report on firm clinical outcomes such as heart attack, stroke, and death. That is why the results from the PREDIMED rand- omized trial published in 2013 were so important. 1 When a Mediterranean diet pattern, supplemented with olive oil or nuts, was evaluated in the PRED- IMED randomized trial, there was a 30% reduction in CVD risk among par- ticipants with and without diabetes. However, there was no mortality advan- tage associated with the intervention diets. This article assesses the association of change in diet quality with total and cause-specific mortality in two large cohorts (Nurses’ Health Study and Health Professionals Follow-Up Study). Consistent with results from published meta-analyses, the authors report that improved diet quality (assessed by the Alternate Healthy Index, Alternate Mediterranean Diet, and the DASH score) over 12 years was consistently associated with a decreased risk of death. These findings further reinforce the health benefits of a dietary pattern that includes high-quality fats (vegetable and fish oils), whole grains, and plenty of fruits and vegetables. Reference 1. Estruch R, Ros E, Salas-Salvado J, et al. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med 2013;368(14):1279-1290.

Abstract BACKGROUND Few studies have evaluated the relationship between changes in diet quality over time and the risk of death. METHODS We used Cox proportional-hazards models to calculate adjusted hazard ratios for total and cause-specific mortality among 47,994 women in the Nurses’ Health Study and 25,745 men in the Health Professionals Follow-up Study from 1998 through 2010. Changes in diet quality over the preceding 12 years (1986-1998) were assessed with the use of the Alternate Healthy Eating Index-2010 score, the Alternate Mediter- ranean Diet score, and the Dietary Approaches to Stop Hypertension (DASH) diet score. RESULTS The pooled hazard ratios for all-cause mortality among participants who had the greatest improvement in diet quality (13 to 33% improvement), as compared with those who had a relatively stable diet quality (0 to 3% improve- ment), in the 12-year period were the following: 0.91 (95% confidence interval [CI], 0.85 to 0.97) according to changes in the Alternate Healthy Eating Index score, 0.84 (95 CI%, 0.78 to 0.91) according to changes in the Alternate Mediter- ranean Diet score, and 0.89 (95% CI, 0.84 to 0.95) according to changes in the DASH score.

A 20-percentile increase in diet scores (indicat- ing an improved quality of diet) was significantly associated with a reduction in total mortality of 8 to 17% with the use of the three diet indexes and a 7 to 15% reduction in the risk of death from car- diovascular disease with the use of the Alternate Healthy Eating Index and Alternate Mediterra- nean Diet. Among participants who maintained a high-quality diet over a 12-year period, the risk of death from any cause was significantly lower – by 14% (95% CI, 8 to 19) when assessed with the Alternate Healthy Eating Index score, 11% (95% CI, 5 to 18) when assessed with the Alternate Mediterranean Diet score, and 9% (95% CI, 2 to 15) when assessed with the DASH score - than the risk among participants with consistently low diet scores over time. CONCLUSIONS Improved diet quality over 12 years was consistently associated with a decreased risk of death. Association of changes in diet quality with total and cause-specific mortality. N Engl J Med 2017 Jul 13;377(2)143-153, M Sotos-Prieto, SN Bhu- pathiraju, J Mattei, et al.

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Dr Keyserling is Professor in the Division of General Medicine and Clinical Epidemiology, Department of Medicine, at the University of North Carolina, Chapel Hill.

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