Stroke is second only to
Stroke is second only to ischaemic nicergoline disease as the leading cause of death worldwide; one in six people will have a stroke in their lifetime. , on October 29, reminds us of these striking facts and the need for individuals to know the risk factors. Although the main risk factors for stroke worldwide—hypertension, smoking, poor diet, and low levels of physical activity—are well established, potential regional variations may well be of importance to national prevention and treatment strategies. These variations could arise from differences in the subtype of stroke (ischaemic or haemorrhagic) prevalent in a particular region, or to the presence of specific epidemiological conditions. These factors are of course likely to be inter-related.
In this month\'s issue, two papers address uncertainties in the burden and risk factors for stroke globally, regionally, and locally. use Global Burden of Disease 2010 methods to estimate trends in the incidence of and mortality and morbidity due to ischaemic and haemorrhagic stroke globally between 1990 and 2010. They show that, although the incidence of both ischaemic and haemorrhagic strokes decreased in high-income countries over these two decades, the incidence of haemorrhagic stroke increased by 22% in low-income and middle-income countries. Although haemorrhagic strokes comprised only a third of all stroke events worldwide, they accounted for more than half of all stroke deaths and 62% of disability-adjusted life-years (DALYs) lost. In 2010, the overwhelming majority (>80%) of haemorrhagic stroke burden, in terms of absolute numbers, deaths, and DALYs lost, was borne by low-income and middle-income countries, particularly central and east Asia and east and southern sub-Saharan Africa. The authors conclude that, to identify those at greatest risk in these regions, “high-quality community-based epidemiological studies in low-income and middle-income countries…are needed…because heterogeneity is likely to exist”.
\' study is one such piece of research. These authors examined stroke risk factors in a prospective case–control study in two regions (urban and rural) of Tanzania. The study confirmed the link with hypertension and smoking, but also produced the striking finding that HIV infection was the biggest independent risk factor (other than previous transient ischaemic attack or stroke). The association could not have been due to any adverse effects of antiretroviral drugs because none of the patients was taking or had ever taken any. This provocative finding, if confirmed, presents a key target for further mechanistic research and for specific interventions in HIV-infected individuals.
Targeted prevention of HIV itself is the focus of the third Article in this issue. \' report is a preplanned assessment of the India AIDS Initiative, Avahan, which was rolled out in 2004 and aimed to reduce HIV transmission in some of India\'s highest-risk groups—female sex workers, men who have multiple male sexual partners, and intravenous drug users. The assessment goes beyond previous attempts to assess the programme\'s population-level effect by estimating the effect of the programme on consistent condom use in the targeted high-risk groups, then using mathematical modelling to estimate the effect of increased condom use on HIV prevalence in south India as a whole. The researchers estimate that around 600 000 HIV infections could have been averted over 10 years of Avahan\'s implementation.
The evidence for the effectiveness of “prevention basics for and by key populations” is overwhelming, states Marie Laga in her . She reminds us that exciting new strategies such as treatment-for-prevention must be accompanied by continued promotion of behavioural strategies that are known to work.
Stroke is the second leading cause of death and the third leading cause of disability-adjusted life-years (DALYs) worldwide. Moreover, the global burden of stroke is increasing. Between 1990 and 2010, the number of stroke-related deaths increased by 26% and DALYs by 19%. Is this epidemic of stroke global or regional, and what is the explanation?