Education, socioeconomic status, and intelligence in childhood and stroke risk in later life: A Meta-analysis

Background: Stroke is the second commonest cause of death, and a common cause of dependency and dementia. Adult vascular risk factors and socioeconomic status (SES) increase stroke risk, but less is known about stroke risk and early life factors, such as education, childhood SES or intelligence (IQ). Methods: We comprehensively searched Medline, PsycINFO and EMBASE from inception to November 2015. We included all studies reporting data on >50 strokes examining childhood/premorbid IQ, SES and education. Two reviewers independently screened full texts, extracted and cross-checked data, including available risk factor-adjustments. We meta-analyzed stroke risk using hazard ratios (HR), odds ratios (OR) and mean differences (MD). We tested effects of study and participant characteristics in sensitivity analyses and meta-regression, assessed heterogeneity and publication bias. Results: We identified 90 studies examining stroke risk and education, SES or IQ (79, 10 and nine respectively) including approximately 161,001 stroke and over 5million stroke-free participants. Stroke risk increased with lower education (OR=1.40, 95% CI=1.28 to 1.53, p<0.001), SES (OR=1.28, 95% CI=1.12 to 1.46, p<0.001) and IQ (HR=1.17, 95% CI=1.00 to 1.37, p=0.04) in studies reporting point estimates, with similar associations for MD. We found minimal publication bias. Between-study heterogeneity was partly explained by participant age and case ascertainment method. Conclusions: Education, childhood SES and intelligence have modest but important influences on lifetime stroke, and hence dementia, risks. Reduction in the global burden of stroke is likely to require societal as well as medical interventions, and underlines the importance of lifetime perspectives on population health.