Coronary heart disease significantly declines between 1983 and 2011

Between 1983 and 2011, the incidence of coronary heart disease decreased by nearly 20 percent, according to an analysis of five observational cohort studies.

The researchers also found that the proportion of coronary heart disease attributable to diabetes decreased in the same time period. In addition, they noted that there was no evidence that the strength of the association between smoking, systolic blood pressure or dyslipidemia and coronary heart disease changed between the two eras.

Lead researcher Ann Marie Navar, MD, PhD, an assistant professor of cardiology at the Duke Clinical Research Institute in Durham, North Carolina, and colleagues published their results online Nov. 13 in JAMA.

“Despite our progress, we still have considerable room for improvement,” Navar said in a news release. “The same risk factors we’ve been battling for years—smoking, high cholesterol, high blood pressure, and diabetes—are still responsible for a large proportion of heart disease. The risk of heart disease in adults with diabetes declined over time, leading to a decrease in the fraction of heart disease attributable to diabetes. But this progress may be offset in the future if the prevalence of diabetes in the population continues to increase.”

The researchers evaluated data on five observational studies available through the National Heart, Lung and Blood Institute Biologic Specimen and Data Repository Information Coordinating Center and created two analytic data sets.

The first set included baseline data collected from 1983 through 1990 and follow-up data from 1996 through 2001. The other set included baseline data collected from 1996 through 2002 and follow-up data from 2007 through 2011.

The researchers then selected participants from each era and matched them based on age, race and sex. The participants were between 40 and 79 years old and did not have cardiovascular disease.

In all, there were 14,009 pairs of participants. The participants in the late era had a lower proportion of adults who smoked, had a systolic blood pressure of 140 mm Hg or greater or had a total cholesterol to high-density lipoprotein (HDL) cholesterol ratio of 4 or greater. The late era had a higher proportion of adults who received blood pressure treatment and lipid-lowering therapy.

During the study, the incidence of new-onset coronary heart disease significantly declined from 1.18 per 100 person-years to 0.98 per 100 person-years.

The researchers defined new-onset coronary heart disease as MI, coronary death, angina or coronary insufficiency.

The hazard ratios of smoking, systolic blood pressure and the ratio of total cholesterol to HDL cholesterol were not significantly different between the eras, although the hazard ratio for diabetes was lower in the later era.

“Risk factors still matter,” Michael J. Pencina, PhD, a study author and director of biostatistics at the Duke Clinical Research Institute, said in a news release. “While the event rates went down and it appears the interventions are working, that doesn’t mean we can ignore the risk factors. There are further gains that could be made if we were to prevent these conditions.”