This study was performed to investigate the prevalence of stroke among residents of the Lanyang Basin on the northeast coast of Taiwan where residents had used well water containing arsenic for more than 50 years. Methods – A total of 8102 men and women had been recruited in the study as a follow-up cohort since 1991 . The status of stroke of study subjects was identified through 5 databases, included the clinical records of Lo-tung Poh-ai Hospital and St. Mary’s Hospital, the prevalence data of cerebrovascular disease from the study of Professor HY Chiou in 1997, and the database of Bureau of National Health Insurance in 1997 and the Death Registry of Taiwan in 2000. Information on consumption of well water, sociodemographic characteristics, cigarette smoking, and alcohol consumption habits, as well as personal and family history of disease was also obtained since 1991. Follow-up interviews were carried out in 1997.
