1. We estimated sex-specific Cox proportional hazards regression functions that related the various risk factor combinations to the incidence of a first hard CHD event in the Framingham Study sample. Ten-year CHD event rates, age-adjusted to the 2000 standard population, were estimated for each risk factor combination in the Framingham Study sample on the basis of 12-year follow-up. We modeled the different risk factor combinations using a set of dummy variables that accounted for the number of optimal, borderline, and elevated risk factors, not the specific risk factors that made up each combination (Appendix). This classification scheme assumes that the hazards posed by borderline or elevated levels of the 5 CHD risk factors are similar. We chose this analytic strategy to facilitate simple yet meaningful interpretation of results. In Cox models incorporating categories of risk factors, with the optimal category serving as the referent, parameter estimates for different elevated risk factors were very similar, and parameter estimates for various borderline risk factors were equivalent, thereby providing support for our strategy. For example, regression coefficients (±SE) for high blood pressure, high levels of low-density lipoprotein cholesterol, low levels of high-density lipoprotein cholesterol, smoking, and diabetes were 0.75 ± 0.19, 0.79 ± 0.22, 0.75 ± 0.22, 0.66 ± 0.15, and 0.62 ± 0.17, respectively, in men. Consequently, absolute CHD event rates were consistent for a given number of borderline and elevated risk factors regardless of the specific combinations of risk factor levels that yielded the number (data not shown). These observations are consistent with our previous report showing that summing the number of risk factors predicts CHD risk reasonably well (23).