Stroke Trends in the WHO MONICA Project

BACKGROUND AND PURPOSE: Stroke registers were established as part of the international collaborative World Health Organization Monitoring of Trends and Determinants in Cardiovascular Disease (WHO MONICA) Project in 17 centers in 10 countries. The aim of the present analyses was to estimate and compare temporal stroke trends across the MONICA populations. METHODS: All stroke events in defined populations were ascertained and validated according to a common protocol and uniform criteria. Almost 25,000 stroke events in more than 15 million person-years were analyzed. Age-standardized rates for fatal stroke and for all stroke events were calculated for whole calendar years for each of the populations. Temporal stroke trends were estimated using annual rates for 5 to 6 years. RESULTS: Annual stroke attack rates decreased among men in 13 populations and among women in 15 of the 17 MONICA populations. Stroke mortality rates declined among men in 11 populations and among women in 14 of the populations studied. The estimated trends reached the level of statistical significance at the 5% level in only a small number of populations. The trends in official cerebrovascular death rates were in agreement with those estimated on the basis of MONICA data in the majority of the populations studied. CONCLUSIONS: Decreasing stroke mortality and attack rates in a large proportion of populations studied can be interpreted as an indication of declining stroke rates in most of the populations studied. The numbers of populations with statistically significant trends were small, and it is therefore not possible to determine with certainty in which of the populations were the changes real.