Poorly educated people are more likely to be admitted to hospital with chronic heart failure than the better educated, even after differences in lifestyle have been taken into account, results from a large European study have suggested.
Researchers followed 18,616 people for as long as 31 years (range 0-31 years, average follow-up was 21 years) between 1976 and 2007 and found that better educated men and women had nearly half the risk of hospital admission for heart failure than the least well educated.
Doctors carried out physical examinations of all the study participants at the time they joined the study and at regular intervals afterwards to check for diabetes, cholesterol levels, blood pressure, blood glucose levels etc.
They also used a questionnaire to assess risk factors that could play a role in the development of heart failure and heart disease, such as smoking, alcohol intake, exercise, or a family history of diabetes or heart disease, etc.
In order to get the most reliable indicator of socioeconomic position, they assessed it by duration of education: less than eight years, 8-10 years, and more than 10 years. In addition, between 2001 and 2003, a random sample of people was assessed using echocardiography, in order to examine the left ventricle of the heart, and systolic and diastolic function.
"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 Prof Prescott.
Dr Eva Prescott, Professor of Cardiovascular Prevention and Rehabilitation at Bispebjerg University Hospital (Copenhagen, Denmark), who led the study and her colleagues found that the most educated men and women had approximately half the risk of heart failure 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 pc lower risk of being admitted to hospital for heart failure compared with people who had been educated for less than eight years, and those who had been educated for between 8-10 years had a 25 pc lower risk. When they looked at the findings from the echocardiography group, the results were similar: people who had been educated for more than 10 years were 39 pc less likely to have any abnormal echocardiography readings, and those educated for 8-10 years were 28 pc less likely when compared with the least educated people.
"There are two important findings from this study. 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 behaviour'," said Prescott.
"The other important finding is that the socioeconomic gradient was seen in echocardiographic indicators of both systolic and diastolic dysfunction. Previous studies have not been able to differentiate between systolic and diastolic heart failure, which have different pathways, but this study points toward a socioeconomic gradient in both subgroups of heart failure."
"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. By adding echocardiography to this study we have a more 'objective' measure than hospital admission. Whether or not you are admitted to hospital for treatment not only depends on disease severity but also on the individual threshold for admission; for example, if you have someone at home to look after you, you may be less likely to be admitted. This could be a source of error in studies such as this. The echocardiography overcomes this problem."
Prof Prescott concluded: "This study shows that deprivation, as measured by levels of education, should be regarded as a risk factor for chronic heart failure in line with what is already known for coronary heart disease, and policy makers should be aware of this when planning social and healthcare provision."
The study has been published online in the European Heart Journal.