Prestroke Vascular Pathology and the Risk of Recurrent Stroke and Poststroke Dementia.

BACKGROUND AND PURPOSE Improved short-term survival after stroke has necessitated quantifying risk and risk factors of long-term sequelae after stroke (ie, recurrent stroke and dementia). This risk may be influenced by exposure to cardiovascular risk factors before the initial stroke. Within the population-based Rotterdam Study, we determined the long-term risk of recurrent stroke and dementia, and the proportion of recurrent strokes and poststroke dementia cases that are attributable to prestroke cardiovascular risk factors (ie, the population attributable risk). METHODS We followed up 1237 patients with first-ever stroke and 4928 stroke-free participants, matched on age, sex, examination round, and stroke date (index date), for the occurrence of stroke or dementia. We calculated incidence rates in both groups and estimated the individual and combined population attributable risk of prestroke cardiovascular risk factors for both outcomes. RESULTS Beyond 1 year after stroke, patients retained a 3-fold increased risk of recurrent stroke and an almost 2-fold increased risk of dementia compared with people without stroke. In total, 39% (95% confidence interval, 18%-66%) of recurrent strokes and 10% (95% confidence interval, 0%-91%) of poststroke dementia cases were attributable to prestroke cardiovascular risk factors. These percentages were similar for first-ever stroke and dementia in the matched stroke-free population. CONCLUSIONS Long-term risks of recurrent stroke and poststroke dementia remain high and are substantially influenced by prestroke risk factors, emphasizing the need for optimizing primary prevention.