Prediction of cardiovascular death in racial/ethnic minorities using Framingham risk factors

Abstract

Background: Risk factors for cardiovascular disease (CVD) derived from the Framingham study are widely used to guide preventive efforts. It remains unclear whether these risk factors predict CVD death in racial/ethnic minorities as well as they do in the predominately white Framingham cohorts.

Methods and results: Using linked data from the National Health and Nutrition Examination Survey III (1988 to 1994) and the National Death Index, we developed Cox proportional hazard models that predicted time to cardiovascular death separately for non-Hispanic white (NHW), non-Hispanic black (NHB), and Mexican American (MA) participants ages 40 to 80 years with no previous CVD. We compared calibration and discrimination for the 3 racial/ethnic models. We also plotted predicted 10-year CVD mortality by age for the three racial/ethnic groups while holding other risk factors constant (3437 NHW, 1854 NHB, and 1834 MA subjects met inclusion criteria). Goodness-of-fit chi(2) tests demonstrated adequate calibration for the 3 models (NHW, P=0.49; NHB, P=0.47; MA; P=0.55), and areas under the receiver operating characteristic curves demonstrated similar discrimination (c-statistics: NHW, 0.8126; NHB, 0.7679; and MA, 0.7854). Older age was more strongly associated with CVD mortality in NHWs (hazard ratio, 3.37; 95% CI, 2.80 to 4.05) than NHBs (hazard ratio, 2.29; 95% CI, 1.91 to 2.75) and was intermediate in MAs (hazard ratio, 2.46; 95% CI, 1.95 to 3.11). Predicted 10-year mortality rate was highest for NHBs across all age ranges and was higher for MAs than NHWs until late in the seventh decade.

Conclusions: Framingham risk factors predict CVD mortality equally well in NHWs, NHBs, and MAs, but the strength of the association between individual risk factors and CVD mortality differs by race and ethnicity. When other risk factors are held constant, minority individuals are at higher risk of CVD mortality at younger ages than NHWs.

Figure 1

Flow diagram of deriving study population.

Figure 2a. Predicted vs. observed 10 year CVD mortality in non-Hispanic whites

Chi-square goodness of fit (4df) = 3.44, p=0.49

Figure 2b. Predicted vs. observed 10 year CVD mortality in non-Hispanic blacks

Chi-square goodness of fit (4df) = 3.56, p=0.47

Figure 2c. Predicted vs. observed 10 year CVD mortality in Mexican-Americans

Chi-square goodness of fit (4df) = 3.04, p=0.55

Figure 3. Predicted mortality by racial/ethnic group across age ranges.*

*Other cardiovascular risk factors (age, gender, systolic blood pressure, total cholesterol, HDL cholesterol, smoking, and diabetes) were held fixed at the mean levels of the entire cohort.