Serum Insulin-Like Growth Factor 1 and the Risk of Ischemic Stroke: The Framingham Study
AbstractBackground and Purpose—
Low insulin-like growth factor 1 (IGF-1) has been associated with increased risk of atherosclerosis and atrial fibrillation in cross-sectional studies. Yet, prospective data linking IGF-1 levels to the development of ischemic stroke remain inconclusive. We examined prospectively the association between serum IGF-1 levels and incident ischemic stroke.Methods—
We measured serum IGF-1 levels in 757 elderly individuals (mean age 79±5, 62% women), free of prevalent stroke, from the Framingham original cohort participants at the 22nd examination cycle (1990–1994) and were followed up for the development of ischemic stroke. Cox models were used to relate IGF-1 levels to the risk for incident ischemic stroke, adjusted for potential confounders.Results—
During a mean follow-up of 10.2 years, 99 individuals developed ischemic stroke. After adjustment for age, sex, and potential confounders, higher IGF-1 levels were associated with a lower risk of incident ischemic stroke, with subjects in the lowest quintile of IGF-1 levels having a 2.3-fold higher risk of incident ischemic stroke (95% confidence interval, 1.09–5.06; P=0.03) as compared with those in the top quintile. We observed an effect modification by diabetes mellitus and waist–hip ratio for the association between IGF-1 and ischemic stroke (P<0.1). In subgroup analyses, the effects were restricted to subjects with diabetics and those in top waist–hip ratio quartile, in whom each standard deviation increase in IGF-1 was associated with a 61% (hazard ratio, 0.39; 95% confidence interval, 0.20–0.78; P=0.007) and 41% (hazard ratio, 0.59; 95% confidence interval, 0.37–0.95; P=0.031) lower risk of incident ischemic stroke, respectively.Conclusions—
IGF-1 levels were inversely associated with ischemic stroke, especially among persons with insulin resistance.