Supplementary Material for: Family History: Impact on Coronary Heart Disease Risk Assessment beyond Guideline-Defined Factors

Objective: Family history (FH) provides insights into the effects of shared genomic susceptibilities, environments and behaviors, making it a potentially valuable risk assessment tool for chronic diseases. We assessed whether coronary heart disease (CHD) risk assessment is improved when FH information is added to other clinical information recommended in guidelines. Methods: We applied logistic regression analyses to cross-sectional data originally obtained from a UK study of women who delivered a live-born infant between 1951 and 1970. We developed 3 models: Model 1 included only the covariates in a guideline applicable to the population, Model 2 added FH to Model 1, and Model 3 included a fuller range of risk factors. For each model, its ability to discriminate between study subjects with and those without CHD was evaluated and its impact on risk classification examined using the net reclassification index. Results: FH was an independent risk factor for CHD (odds ratio = 1.7, 95% confidence interval = 1.26-2.47) and improved discrimination beyond guideline-defined clinical factors (p < 0.0006). However, the difference in the area under the curve of 2.8% and the extent of patient reclassification resulting from the inclusion of FH were small (p = 0.11). Conclusion: While FH were a significant independent risk factor for CHD, it added little to risk factors typically included in guidelines.