SAN DIEGO — People of all social classes reduced their risk of heart disease equally in recent years, but the uneducated and poor still face the greatest threat, scientists reported Thursday.

The study suggests that efforts to persuade people to change disease-causing habits should be aimed at the least educated sectors of society, said Dr. Russell Luepker, chief author of the study.

“If we’re going to continue to make progress, we have to target those groups who have been least affected by improvements in society,” said Luepker, chief author of the study an a professor of epidemiology and medicine at the University of Minnesota.