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PURE Healthy Diet Score validated

 

Key clinical point: The PURE Healthy Diet Score correlated with survival and cardiovascular events in three new databases.

Major finding: The highest-scoring quintiles had about 25% fewer deaths, MIs, and strokes, compared with the lowest-scoring quintiles.

Study details: The PURE Healthy Diet Score underwent validation using three independent data sets with a total of 79,478 people.

Disclosures: Dr. Mente had no financial disclosures.

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Despite validation, questions remain

Dr. Mente and his associates have validated the PURE Healthy Diet Score. However, it remains unclear whether the score captures all of the many facets of diet, and it’s also uncertain whether the score is sensitive to changes in diet.

Dr. Eva Prescott, cardiologist, Bispepjerg Hospital, Copenhagen Mitchel L. Zoler/MDedge News

Dr. Eva Prescott

The researchers developed the PURE Healthy Diet Score with data from PURE, a large, international study. Their findings were controversial when first reported in 2017. Controversy arose over at least three of their findings: Decreased mortality was linked with increased consumption of saturated fat from dairy and red meat; higher scores did not correlate with a significant effect on cardiovascular disease in the derivation study; and the benefit from fruits and vegetables in the diet hit a plateau with an intake of about four daily servings. Their finding that decreased mortality linked with an increased intake of saturated fat ran counter to expectations.

Another issue with the quintile analysis that the researchers used to derive the formula was that the spread between the median scores of the bottom, worst-outcome quartile and the top, best-outcome quartile was only 7 points on a scale that ranged from 7 to 35. The small magnitude of the difference in scores between the bottom and top quintiles might limit the discriminatory power of this scoring system.

Eva Prescott, MD, is a cardiologist at Bispebjerg Hospital in Copenhagen. She has been an advisor to AstraZeneca, NovoNordisk, and Sanofi. She made these comments as designated discussant for the report.


 

REPORTING FROM THE ESC CONGRESS 2018

– A formula for scoring diet quality that during its development phase significantly correlated with overall survival received validation when tested using three independent, large data sets that together included almost 80,000 people.

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With these new findings the PURE Healthy Diet Score had now shown consistent, significant correlations with overall survival and the incidence of MI and stroke in a total of about 218,000 people from 50 countries who had been followed in any of four separate studies. This new validation is especially notable because the optimal diet identified by the scoring system diverged from current American diet recommendations in two important ways: Optimal food consumption included three daily servings of full-fat dairy and 1.5 servings daily of unprocessed red meat Andrew Mente, PhD, reported at the annual congress of the European Society of Cardiology. He explained this finding as possibly related to the global scope of the study, which included many people from low- or middle-income countries where average diets are usually low in important nutrients.

The PURE Healthy Diet Score should now be “considered for broad, global dietary recommendations,” Dr. Mente said in a video interview. Testing a diet profile in a large, randomized trial would be ideal, but also difficult to run. Until then, the only alternative for defining an evidence-based optimal diet is observational data, as in the current study. The PURE Healthy Diet Score “is ready for routine use,” said Dr. Mente, a clinical epidemiologist at McMaster University in Hamilton, Canada.

Dr. Andrew Mente

Dr. Mente and his associates developed the Pure Healthy Diet Score with data taken from 138,527 people enrolled in the Prospective Urban Rural Epidemiology (PURE) study. They published a pair of reports in 2017 with their initial findings that also included some of their first steps toward developing the score (Lancet. 2017 Nov 4; 380[10107]:2037-49; 380[10107]:2050-62). The PURE analysis identified seven food groups for which daily intake levels significantly linked with survival: fruits, vegetables, nuts, legumes, dairy, red meat, and fish. Based on this, they devised a scoring formula that gives a person a rating of 1-5 for each of these seven food types, from the lowest quintile of consumption, which scores 1, to the highest quintile, which scores 5. The result is a score than can range from 7 to 35. They then divided the PURE participants into quintiles based on their intakes of all seven food types and found the highest survival rate among people in the quintile with the highest intake level for all of the food groups.

The best-outcome quintile consumed on average about eight servings of fruits and vegetables daily, 2.5 servings of legumes and nuts, three servings of full-fat daily, 1.5 servings of unprocessed red meat, and 0.3 servings of fish (or about two servings of fish weekly). Energy consumption in the best-outcome quintile received 54% of calories as carbohydrates, 28% as fat, and 18% as protein. In contrast, the worst-outcomes quintile received 69% of calories from carbohydrates, 19% from fat, and 12% from protein.

In a model that adjusted for all measured confounders the people in PURE with the best-outcome diet had a statistically significant, 25% reduced all-cause mortality, compared with people in the quintile with the worst diet.

To validate the formula the researchers used data collected from three other trials run by their group at McMaster University:

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