Social-Biological Differences Across the Lifespan and Risk of Stroke Incidence: A Life Course Epidemiology Analysis

Objectives: We aimed to examine the complex association of social-biological differences across the lifespan with risk of stroke incidence using a nationally representative study sample.

Methods: Participants aged >=50 years (n=24,064), recruited between 1992 and 2008 in the Health Retirement Study, were followed on average 9.7 years. Stroke incidence was defined as self-report of a physician-diagnosis of first stroke. Socioeconomic status (SES) in childhood was assessed using parents' education level. Social-biological status in adulthood was assessed by subjects' education level, body mass index (BMI), and chronic non-communicable disease. Associations between social-biological factors and stroke incidence were examined prospectively using multivariate Cox's regression models.

Results: Within the follow-up period, a total of 2,358 first stroke incidence were diagnosed. African Americans had the highest incidence rate (11.3%), followed by White (9.87%), Hispanic (7.35%), and others (6.62%). Multivariate Cox's models indicated that poor SES in childhood, and poor SES and worse health conditions in adulthood significantly predicted risk of stroke. The hazard ratios (95%CI) of mother's education (<9 yrs), and participants' education (<9 yrs), increased BMI (30 or higher kg/m2), and having hypertension, heart disease and/or diabetes for the risk of stroke were 1.31 (1.19-1.44), 1.44 (1.27-1.64), and 1.54 (1.41-1.68), 1.58(1.42-1.76), 1.48 (1.35-1.62), and 2.01 (1.78-2.27) respectively. Conclusions: The study provides further evidence for the association of poor SES and health conditions in early life with risk of stroke in later life. This finding highlights that prevention initiatives across the lifespan may lead to a substantial risk reduction of stroke incidence in later life.