June 9, 2016

expert reaction to study investigating the global risk factors for stroke

A systematic analysis of the Global Burden of Disease Study 2013 published in The Lancet Neurology reports that modifiable risk factors, such as behavioural and environmental factors, contribute to 90% of the global stroke burden.

Dr Tim Chico, Reader in Cardiovascular Medicine & consultant cardiologist, University of Sheffield, said:

“This study combines information from a huge array of sources to try to provide an informed estimate of the relative contribution of different influences on the risk of stroke. Although there is always some uncertainty about such estimates, this study represents probably the most comprehensive attempt at understanding the extent to which multiple risk factors promotes stroke and other diseases.

“Although the press release and editorial highlight the impact of air pollution on stroke risk, this relative importance of this was much lower in Western Europe (and the UK) compared with less developed countries, in part because a lot of such air pollution comes from cooking over open fires using coal, wood, or dung.

“For me, the most relevant finding to the UK is that around 70% of strokes are associated with things that an individual can definitely address; smoking, low levels of physical activity, and poor diet (low in vegetables fruit, and whole grains), and this is entirely consistent with lots of other studies.”

Dr Patrick McSharry, Head of Catastrophe Risk Financing & statistician, University of Oxford, said:

“This extensive study across 188 countries between 1900 and 2013 employs robust statistical analyses to determine the most significant stroke risk factors.  Environmental and household air pollution is responsible for almost one third of the global disability linked to stroke. While also responsible for global warming, air pollution has increased the stroke burden by 33% over the last quarter of a century.

“Although air pollution is generally a greater risk factor in developing countries (33.7% compared to 10.2% for developed countries), environmental pollution (10.2%) was strikingly higher than previously established risk factors such as alcohol (6.8%) and high cholesterol (5.4%) in the UK.

“The top five risk factors in the UK are high blood pressure (47.7%), high body mass index (27.1%), diet low in fruit (25.1%), diet low in vegetables (23.1%) and smoking (14.7%). Low physical activity is another prominent risk factor (11.6%) that increases for adults over 70. A positive finding for policymakers is that 90% of the stroke burden is attributed to modifiable risk factors. This suggests that behaviour change strategies using taxation and education to promote a healthy diet and regular exercise could dramatically decrease the stroke burden in the UK.”

‘Global burden of stroke and risk factors in 188 countries, during 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013’ by Feigin et al. published in The Lancet Neurology on Thursday 9th June. 

Declared interests

Dr Tim Chico: “I am a committee member and Treasurer of the British Atherosclerosis Society, a charity established in 1999 to promote UK atherosclerosis research.”

Dr Patrick McSharry: No conflicts of interest to declare