Family history as a risk factor for early-onset stroke/transient ischemic attack among adults in the United States.

BACKGROUND Stroke is a major cause of morbidity and death in the United States. We tested the association between familial risk for stroke and prevalence of the disease among US adults and assessed the use of family history of stroke as a risk assessment tool for the disease. METHODS Using data from the 2005 HealthStyles survey (n = 4,819), we explored the association between familial stroke risk (stratified as high, moderate or low) and the prevalence of stroke and related health conditions. We evaluated the clinical validity (sensitivity, specificity) of family history of stroke as an indicator of stroke risk. Stroke and the related medical conditions were self-reported. RESULTS Independent of other risk factors, people with a high familial risk for stroke were 4 times more likely to have had a stroke (95% confidence interval, CI, 2.6-6.0) than people with moderate or low familial risk. They were also 1.3 times (95% CI 1.1-1.6) more likely to have high blood pressure and 1.5 times (95% CI 1.3-2.0) more likely to have congestive heart failure. The sensitivity and specificity of using family history alone, high blood pressure alone or both risk factors to estimate stroke risk were 52 and 83%, 53 and 74%, and 29 and 95%, respectively. CONCLUSIONS Despite several limitations typical of self-reported surveys, we find that in this sample of US adults, family history of stroke was significantly associated with the risk for stroke and high blood pressure as well as related conditions. Family history of stroke, alone or combined with other risk factors, can be a useful tool in assessing stroke risk among US adults.