Stroke in Asia: geographical variations and temporal trends.

Asian countries are in various stages of epidemiological transition and therefore exhibit a great diversity in disease patterns. Collectively, they comprise almost two-third of the world's total mortality due to stroke. The purpose of this review is to explore existing epidemiological data on stroke, highlight the temporal trends in stroke epidemiology in various regions of Asia and predict future patterns based on these observations. Our search revealed that there is a lack of good epidemiological data from most Asian countries. Whatever data exist are not comparable due to lack of standardised methodology for ascertaining stroke and its subtypes. For this and other reasons, these estimates exhibit country-to-country variation and also within-country variability. We have also reviewed temporal trends in stroke incidence and prevalence in 12 Asian countries and the evolution of stroke subtypes over the past two decades. Important observations include a rise in stroke incidence in most Asian countries, an earlier age at onset compared with the West, a relative increase in the proportion of ischaemic strokes and a decline in haemorrhagic strokes. Among ischaemic stroke subtypes, lacunar strokes, which were once the commonest variety, are now declining. Emerging data suggest that large artery atherosclerosis and in particular that of intracranial vessels is the predominant aetiology in most Asian countries. The review also identified important gender differences in terms of stroke risk factors, prevalence and outcomes. There is need for sound epidemiological data from most countries to understand the disease better and plan policy-level interventions to decrease the burden. We identify a need for standard format or guidelines for conducting stroke epidemiological studies especially in developing Asian countries. This region must be identified as a priority region for stroke-related interventions and preventive strategies by global healthcare authorities and organisations. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.