Since 1979, coronary heart disease mortality rates have significantly decreased in the U.S., although they differ depending on age and sex.

The rates for men and women under age 55 have remained relatively consistent and stagnated since 2000, according to a study published online in Circulation on Aug. 24. During that same time period, the rates for people 65 and older have rapidly declined.

Lead researcher Viola Vaccarino, MD, PhD, of Emory University, and her colleagues obtained data from all U.S. adults who were 25 or older and died from 1979 to 2011. The records included the cause of death and demographic information.

Although the study could not provide definitive reasons for the rate differences based on age and sex, Vaccarino was concerned with the lack of progress shown among the younger age category.

“We didn’t have data to identify the causes of this, but one thing that we can tell based on other research is most likely these trends reflect differences in lack of adequate prevention efforts in young people versus other groups,” Vaccarino told Cardiovascular Business. “Other studies have found mortality rates after hospitalized heart disease have declined pretty well in all age groups. It’s not like we’re treating women less well or they’re responding to treatment less well. It’s probably the fact that we’re not preventing heart disease or heart disease risk factors among young people, particularly young women.”

During the time period analyzed, the age-adjusted coronary heart disease mortality rates declined 68 percent for men and women. From 1979 to 2011, the rates fell from 703 to 225 deaths per 100,000 in men and from 395 to 125 deaths per 100,000 in women. However, the trends varied depending on age.

Among men younger than 55, the death rates declined by 5.5 percent per year from 1979 to 1989, fell by 1.2 percent from 1990 to 1999 and decreased by 1.8 percent from 2000 to 2011.

Among women younger than 55, the death rates declined by 4.6 percent per year from 1979 to 1989, increased by 0.1 percent from 1990 to 1999 and decreased by 1 percent from 2000 to 2011.

For adults 65 and older, the death rates declined more rapidly in recent years. Among men in that age category, the death rates declined by 2.6 percent per year from 1979 to 1989, fell by 2.1 percent from 1990 to 1999 and decreased by 4.4 percent from 2000 to 2011. Among women age 65 and older, the death rates declined by 1.7 percent per year from 1979 to 1989, fell by 1.6 percent from 1990 to 1999 and decreased by 5.0 percent from 2000 to 2011.

Vaccarino said another potential reason for the stagnation among younger people is that the prevalence of heart disease risk factors such as obesity and diabetes have increased in the past decade.

The researchers are interested in studying the role non-traditional risk factors such as stress and depression play in the risk of heart disease and adverse outcomes among younger women.

“[The stagnation in heart disease death rates] could be due to an environment where young women in this era in this country live in terms of having a lot of demands,” Vaccarino said. “Work, home and the socioeconomic conditions of many women are not as good as that of their male counterparts. These kind of competing demands and psychosocial stressors may potentially play a role, as well.”