HF incidence dips in Ontario, but prognosis remains poor
Darwin F. Yeung, MD, of the Institute for Clinical Evaluative Sciences in Toronto, and colleagues conducted a population-based study of patients in Ontario diagnosed with HF between April 1997 and March 2008. They used the Canadian Institute for Health Information’s Discharge Abstract Database to obtain inpatient data and Ontario Health Insurance Plan physician claims to get outpatient data. They defined an HF event as either one documented admission for HF or one outpatient claim for HF that was followed by at least one more HF claim within a year.
Their outcome measures included 30-day and one-year readmission rates and mortality after the first HF event. To determine deaths, they used the Ontario Registered Persons database. They tracked outcomes through linked databases. The researchers standardized admission and outpatient visit rates by age and sex and calculated rates per 100,000 people (20 years old and older) per year.
Yeung and colleagues identified 419,551 incident HF cases in the 10-year period (216,190 inpatient and 203,361 outpatient). The inpatient group was on average older and had more comorbidities. Median age between 1997 and 2007 increased by two years in the inpatient group and by one year in the outpatient group. The prevalence of diabetes and hypertension increased in both groups over the 10-year span while the prevalence of ischemic heart disease decreased in both groups.
The HF incidence rate dropped from 454.7 cases per 100,000 people in 1997 to 306.1 cases per 100,000 people in 2007, for an average annual decline of 3 percent. But one-year risk-adjusted mortality decreased only modestly over the 10-year period, from 35.7 percent to 33.8 percent in the inpatient group and from 17.7 percent to 16.2 percent in the outpatient group.
“The inclusion of outpatients is important because this group accounts for about half of all new cases of heart failure in Ontario,” Yeung et al wrote. “Although there was a comparable and steady decline in the incidence of heart failure in both the inpatient and outpatients settings and among both men and women, the oldest age cohorts had the largest declines.”
The authors observed that the 32.7 percent decline in incidence of HF paralleled similar rates of decline seen in cardiovascular disease mortality and incidence in ischemic heart disease in Canada. They noted that ischemic heart disease is the leading cause of HF, and hypothesized that the decline in ischemic heart disease may be driving much of the drop in HF incidence. Among other trends, they looked at improved interventions for MI and successful efforts to control hypertension in Ontario as contributors to lower HF incidence.
Despite the decline in incidence of HF, the authors saw storm clouds on the horizon. “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 in heart failure to plateau or reverse.”
Importantly, their study found that the prognosis for HF patients has remained poor.
They wrote that methodology using the two-claim approach to identify HF claims may have underestimated the incidence of HF and that outpatient claims are less reliable than inpatient discharge data for capturing comorbid conditions. Due to data limitations, they could not address the severity of HF.