Jama logoA study apparently reported, a 35 percent decrease in the death rate from coronary heart disease (CHD) from1994 to 2005 in Ontario, Canada. It was also reported that, about half of this reduction was associated with improvements, in traditional CHD risk factors such as total cholesterol levels and systolic blood pressure. This further prompted the Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada, to undertake a study. This study was conducted, in order to know the association of CHD prevention and treatment strategies with the decline in CHD mortality in Ontario.

The study was undertaken on individuals aged 25 to 84 years. They used a model that amalgamated data on population size, CHD mortality, risk factors and changes in the use of treatments. The investigators then scrutinized, the relative risks and quantified the relationship between CHD mortality and two factors.

The first one included, evidence-based therapies in 8 distinct CHD subpopulations, like acute myocardial infarction [AMI; heart attack], acute coronary syndromes, secondary prevention post-AMI, chronic coronary artery disease, heart failure in the hospital vs. in the community, and primary prevention for hyperlipidemia or hypertension. And the other factor was population trends in 6 risk factors like smoking, diabetes mellitus, systolic blood pressure, plasma cholesterol level, exercise, and obesity.

Harindra C. Wijeysundera, M.D., of the Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada, and his colleagues explained, “Coronary heart disease remains the most common cause of death worldwide and generates a large economic burden. Rates of CHD mortality have decreased substantially over the last 3 decades. Identifying the underlying factors associated with this decline is critical for planning future health policy, and prioritizing strategies for primary and secondary prevention.”

The investigators concluded that, CHD mortality rate in Ontario decreased by 35 percent between 1994 and 2005. It was reduced from 191 to 125 deaths per 100,000 inhabitants, translating to an estimated 7,585 fewer CHD deaths in 2005. The decrease seemed to be faced by the older patients aged 75 to 84. With changes in risk factors, a 48 percent decrease of the total mortality rate was registered. This may have accounted for 3,660 fewer CHD deaths. New and surgical treatments were associated with 43 percent of the decrease. This further probably prevented or delayed 3,280 deaths.

However, the most important and ample improvements were contributed, from the management of patients with chronic stable coronary artery disease. They helped in reducing approximately, 1,305 deaths, which accounted for a total reduction of 17 percent. The percentage of patients, with chronic stable coronary artery disease, who were taking statins increased from 8 percent in 1994 to 78 percent in 2005.The researchers noted improvements in the treatment of patients with heart failure in the community were associated with approximately 750 fewer deaths that made a total of 10 percent. In 1994, 29 percent of patients were taking beta-blockers, which further increased to 67 percent in 2005. This improvement in treatment, displayed a total of 8 percent, overall prevented or delayed death among AMI patients.

The investigators quoted, “Although our study was not designed to establish a causal relationship between these trends and mortality, these results may inform decision making at all levels with the goal of ensuring that the gains in CHD mortality reduction during the previous decade are not lost in the next decade.”

Hence, over a period of years, there appeared a reduction in the average total cholesterol level, among the people of Ontario. There were 1,730 CHD deaths, being prevented or delayed. This symbolized an overall reduction of 23 percent in CHD mortality. Also, a decrease in average systolic blood pressure from 1994 to 2005 was noted. This displayed a reduction, of 20 percent of the total deaths preventing 1,545 deaths after extracting deaths that were overcome due to advanced pharmacological therapies.

The authors also highlighted that, increasing diabetes prevalence and body mass index had an inverse relationship associated with higher CHD mortality of 6 percent and 2 percent, respectively. The study seems to be enlightening and can be proved essential while making decisions at all levels with the aim of reducing deaths caused by CHD.

The study is published in the May 12 issue of JAMA.