More than half of heart diseases linked to lifestyle factors

A study involving 1.5 million people has proven that five classic risk factors — overweight, high blood pressure, high cholesterol, smoking and diabetes mellitus — are linked to more than half of cardiovascular diseases worldwide.

Conducted by the Global Cardiovascular Risk Consortium, the study assessed the individual-level data of people from 34 countries, including Australia, to gain a better understanding of the significance of the individual risk factors and overall mortality in order to derive targeted preventative measures.

Preventable risk factors

“Our study clearly shows that over half of all heart attacks and strokes are avoidable by checking and treating the classic risk factors. These results are of the highest significance for strengthening prevention in this area. At the same time, approximately 45% of all cardiovascular cases cannot be explained with these risk factors; they should motivate us and the academic funders to further research efforts,” said Professor Doctor Stefan Blankenberg, the medical director of the University Heart & Vascular Center at the UKE.

Cardiovascular diseases develop silently over decades and cause approximately a third of all deaths worldwide. Frequently without being recognised, the vascular walls change, giving rise to arteriosclerosis, in the wake of which coronary heart disease may occur, including complications such as heart attacks, acute cardiac death or strokes.

All five risk factors combined (overweight, high blood pressure, high cholesterol, smoking and diabetes mellitus) accounted for 57.2% of women’s cardiovascular risk and 52.6% of men’s. Thus, a substantial share of cardiovascular risk remains unexplained. In comparison, the five risk factors merely account for about 20% of the risk of death.

“In principle, the five classic risk factors that we examined are modifiable, and thus responsive to preventive measures. So far, the proportion of preventable risk attributed to these five risk factors is still a matter of debate,” said lead author and associate professor Dr Christina Magnussen, Department of Cardiology at the University Heart & Vascular Center of the UKE.

Regional differences

There were differences in the frequency of the risk factors across the eight global regions part of the study. Latin America had the highest rates for overweight and Europe had the highest values for high blood pressure and high cholesterol. The risk factor smoking was particularly decisive in Latin America and Eastern Europe, and diabetes mellitus in North Africa and in the Middle East.

Furthermore, the study also clearly shows a linear relation between high blood pressure, and high cholesterol, and the occurrence of cardiovascular diseases, according to the researchers. The higher the values, the higher the likelihood of the occurrence of cardiovascular diseases.

The significance of all risk factors decreases with age; for example, high blood pressure is more damaging to a 40- than an 80-year-old. The body mass index (BMI) is the only exception and remains equally significant at any age.

“This raises the question to which extent the target values for treating cardiovascular risk factors for the most elderly should be identical with those for the middle to older age bracket,” Blankenberg said.

The study conducted under the auspices of the Department of Cardiology at the University Heart & Vascular Center of the Medical Center Hamburg-Eppendorf (UKE) and the German Center for Cardiovascular Research (DZHK) involved the University of Queensland, the University of Melbourne, Baker Heart and Diabetes Institute, the University of Sydney, The George Institute for Global Health and the University of New South Wales.

“With my personal keen interest in improving blood pressure control in Australia and globally (also as Co-Chair of the Hypertension Taskforce of Australia), it was remarkable to see in this study that high systolic blood pressure was again identified to ‘offer the greatest potential for cardiovascular disease prevention’. Elevated systolic blood pressure appeared to be the largest contributor to CVD development in all eight geographic regions represented in the study,” said Alta Schutte, Professorial Fellow at The George Institute for Global Health and SHARP Professor and Principal Theme Lead: Cardiac, Vascular and Metabolic Medicine at UNSW Sydney.

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