Stroke surveillance: an overview.

Stroke surveillance is the gateway to information about etiology, risk, prognosis, prevention and intervention as well as disease distribution and time trends. While most stroke surveillance has focused on mortality, there is an increasing need to know what the impact is on the community of stroke incidence and prevalence. Available retrospective and prospective surveillance methodologies each have advantages and disadvantages with respect to validity, reliability, precision and cost. Hospital-based stroke surveillance is generally inadequate for population-based incidence estimations. International studies require a large investment in management in order to maintain adequate data quality standards and to ensure subsequent comparability. A major challenge to stroke surveillance is accurate subtyping. Where computerized databases exist, record linkage can provide the means to develop a cost-effective surveillance system. There is a need for strategies to enhance national surveillance systems on the basis of innovations and advances derived from research.