DECLINING INCIDENCE OF STROKE

A major decline in the incidence of stroke occurred in the population of Rochester, Minnesota, during the period 1945 to 1974. For every 100 first episodes of stroke that occurred per unit of population during the period 1945–49, only 55 occurred in the period 1970–74. Although the decline was present in both sexes and in all age groups, the reduction in rates was more pronounced in the elderly. There was no major change in age at onset. Analysis of cohorts born during successive five-year periods from 1865 to 1915 confirmed the decreasing incidence rate in all age groups. (N Engl J Med 300:449–452, 1979) ARE strokes on the decline? Analysis of mortality statistics undertaken in several countries during the past two decades suggests that they are.1 2 3 4 5 6 However, limitations imposed by changes in diagnostic fashion,7 coding practice,8 coverage in death certification9 and low accuracy of diagnoses10 make it difficult to interpret trends based on mortality statistics. These sources are accepted only because no other data are usually available to confirm the clinical impression that the frequency of stroke has been changing. Morbidity statistics based on the actual occurrence of stroke give more accurate information. Several such studies have been undertaken,11 12 13 14 15 but the problems of comparability. © 1979, Massachusetts Medical Society. All rights reserved.