Diabetes and lifetime risk of stroke and subtypes in an urban middle-aged population

Lifetime risk (LTR) is defined as the cumulative probability of developing a disease in one's remaining lifetime from a given index age. The impact of diabetes on the LTR of stroke events in Asians, where stroke incidence is higher than for Westerners, has not been estimated yet. These estimates can be useful for diabetes knowledge translation activities.

All participants who were stroke-free at baseline in the Suita Study, a cohort study of cardiovascular diseases in Japan, were included in the study sample. Age, in years, was used as the time-scale. Age-specific incidence rates were calculated using the person-years method within five-year bands. We estimated the sex- and index-age-specific LTR of first-ever stroke accounting for the competing risk of death.

In this cohort study, we followed 5515 participants from 1989 to 2007 for 71,374.23 person-years. At age 40, the LTRs, adjusted for competing risk of death, for all strokes were 15.98% for men without diabetes and 26.64% for men with diabetes. The LTR for stroke was 10.66% higher for men with diabetes than men without diabetes. For women of same index age, the LTR of stroke was 17.29% and 30.72% with diabetes and without diabetes, respectively. The difference in LTR between persons with diabetes and without diabetes was 13.43%. This increased LTR of strokes for persons with diabetes was observed among both men and women across all index ages. Similar results were observed for cerebral infarction stroke subtype.

In this urban community-based population we observed that diabetes has a significant effect on the residual LTR of stroke for both men and women of middle age. This knowledge can be used to inform public health education and planning.