The study, in Monday's Canadian Medical Association Journal, indicates the number of new cases of heart failure in the province declined 32.7 per cent between April 1, 1997 and March 31, 2008.
That translates to a three per cent average annual decline — similar to the drop in rates noted in other studies on the overall rate of death from cardiovascular disease and the incidence of ischemic heart disease events in Canada, writes lead author Dr. Jack Tu of the Institute for Clinical Evaluative Sciences (ICES) and Sunnybrook Health Sciences Centre in Toronto.
In an interview Monday with CBC News, Tu said heart failure is the leading cause of people returning to hospital, and the downside of that is they often spend the last few years of their lives visiting hospitals.
"It's worse than most cancers in terms of prognosis," he said. "So one of the most important things to do is to prevent heart failure, which is very serious."
Despite the CMAJ study's finding, determined by assessing a large group of people diagnosed with the disease who were representative of the population, the researchers caution that the rates of death remain high.
Researchers looked at trends in heart failure in Ontario from 1997 to 2007 in a large group representative of the population, between ages 20 and 105, taken from the Ontario Health Insurance Plan (OHIP) database. There were 419,551 cases of heart failure — 216,190 requiring admission to hospital and 203,361 managed as outpatients at the time of initial diagnosis. Most studies of heart failure trends have not included outpatients.
Slightly more women (51 per cent) than men were identified and 80 per cent of the overall cohort were age 65 or older.
"The causes of heart failures differ between men and women, but it's still more common in men than women," Tu told CBC News. "But overall, heart failure is an equal-opportunity killer, and we really do need to try to prevent its development in both genders."
The Ontario researchers point out that heart-failure rates also seem to be dropping in other parts of the world, such as western Europe, Australia, New Zealand and the U.S., where they rapidly increased before the mid-1990s. The decline is reflected in hospital reports on reductions in the number of admissions of people with the disease.
"Our study is the largest and most recent population-based study to address this issue, and provides strong evidence that the incident of heart failure is decreasing," the CMAJ study says.
Health campaigns seem to work
Stepped-up campaigns highlighting the dangers of smoking, and the importance of controlling blood pressure and cholesterol, which can lower the rates of ischemic heart disease, a leading cause of heart failure, "may have been at least partially successful" in the number of people diagnosed with heart failure for the first time during the decade studied, the researchers conclude.
"Hypertension [high blood pressure] is the second most important cause of heart failure and other studies have shown that Ontario has one of the highest rates of blood pressure control in recent years, which may also contribute to fewer patients with incident heart failure," the authors write.
"Although the results of our study are encouraging, the population continues to age and risk factors for heart failure such as diabetes and obesity are increasing, particularly in young people, which may cause the downward trend in incidence of heart failure to plateau or reverse," they warn.
"The greatest decline in incidence [reported in the CMAJ study] occurred among the older cohorts, but it is the younger cohorts that will determine future trends in incidence."
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