EHJ: Socioeconomics, education affect HF hospitalization

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Poorly educated people are more likely to be admitted to the hospital with chronic heart failure (CHF) than the better educated, even after differences in lifestyle have been taken into account, based on a study published online Dec. 9 in the European Heart Journal.

With increasing socioeconomic disparity in cardiovascular risk factors, there is a need to assess the role of socioeconomic factors in CHF and to what extent this is caused by modifiable risk factors, according to the study’s senior author Eva Prescott, MD, professor of cardiovascular prevention and rehabilitation at Bispebjerg University Hospital in Copenhagen, Denmark, and colleagues.

This study examines the “relationship between socioeconomic factors and the risk of developing heart failure," said Prescott. "Although it is well known that socioeconomic deprivation is associated with coronary heart disease, much less is known about the link with the development of CHF."

In a prospective cohort of 18,616 men and women without known MI or CHF examined in 1976 to 1978, 1981 to 1983, 1991 to 1994, and 2001 to 2003 in the Copenhagen City Heart Study, the researchers studied the effect of education on CHF incidence. During a median follow-up of 21 years, 2,190 participants were admitted to the hospital for CHF.

Age-adjusted hazard ratio (HR) for intermediary (eight to 10 years) and high level of education (10 years) with low (eight years) as reference was 0.69 and 0.52, respectively, with similar associations in men and women.

Prescott and colleagues found that the most educated men and women had approximately half the risk of HF compared with the least educated. After they had adjusted for various cardiovascular risk factors, they found that people who had been educated for more than 10 years had a 39 percent lower risk of being admitted to the hospital for HF compared with people who had been educated for less than eight years, and those who had been educated for between eight to 10 years had a 25 percent lower risk.

"We used echocardiography as a more reliable way of detecting signs of heart failure, since analyses of hospital admissions may exaggerate the effect of social deprivation because of a possible lower threshold for hospital admission in the relatively deprived," said Prescott.

In a random subset of the population examined with echocardiography in 2001 to 2003, they found that education was associated with left ventricular (LV) hypertrophy, LV dilatation, reduced LV ejection fraction and severe diastolic dysfunction (P for trend, 0.05), whereas no association was found for mild diastolic dysfunction (P for trend, 0.61). With the exception of LV hypertrophy, significant associations persisted after adjustment for potential mediating factors.

When the researchers looked at the findings from the echocardiography group, the results were similar: people who had been educated for more than 10 years were 39 percent less likely to have any abnormal echocardiography readings, and those educated for eight to 10 years were 28 percent less likely when compared with the least educated people.

“Only a minor part of the excess risk was mediated through traditional cardiovascular risk factors,” the authors wrote.

"There are two important findings from this study,” Prescott said. “The first is that the clear socioeconomic gradient in risk of developing heart failure found in this and in other studies is not explained by differences in lifestyle. Thus, we must look for other explanations, which potentially include differences in treatment of patients; for instance, perhaps the socioeconomically deprived do not receive the same standard of treatment as the more affluent. We cannot conclude this based on our study, but we can see that we must look for explanations other than 'poor behavior.' The other important finding is that the socioeconomic gradient was seen in echocardiographic indicators of both systolic and diastolic dysfunction.”

She added that previous studies have not been able to differentiate between systolic and diastolic HF, which have different pathways, but this study points toward a socioeconomic gradient in both subgroups of HF.

"In addition, since we were using echocardiography to look at early indicators of heart dysfunction in healthy individuals, we were able to show that the socioeconomic gradient is present from early disease stages, years or decades before development of clinical heart failure,” Prescott said. “By adding echocardiography to this study we have a more 'objective' measure than hospital admission. … This could be a source of error in studies such as this. The echocardiography overcomes this problem."

The authors suggested that “strategies to address this inequality should be strengthened.”